diff --git a/Experiments/arrowup/Main.hs b/Experiments/arrowup/Main.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/arrowup/Main.hs
@@ -0,0 +1,83 @@
+{-# LANGUAGE Arrows #-}
+import Graphics.UI.SDL as SDL
+import Graphics.UI.SDL.Primitives as SDL
+import FRP.Yampa as Yampa
+import Data.IORef
+import Debug.Trace
+
+width = 640
+height = 480
+
+main = do
+ timeRef <- newIORef (0 :: Int)
+ reactimate initGraphs
+ (\_ -> do
+ dtSecs <- yampaSDLTimeSense timeRef
+ return (dtSecs, Nothing))
+ (\_ e -> display e >> return False)
+ (fire (fromIntegral height / 2) (-10))
+
+-- | Updates the time in an IO Ref and returns the time difference
+updateTime :: IORef Int -> Int -> IO Int
+updateTime timeRef newTime = do
+ previousTime <- readIORef timeRef
+ writeIORef timeRef newTime
+ return (newTime - previousTime)
+
+yampaSDLTimeSense :: IORef Int -> IO Yampa.DTime
+yampaSDLTimeSense timeRef = do
+ -- Get time passed since SDL init
+ newTime <- fmap fromIntegral SDL.getTicks
+
+ -- Obtain time difference
+ dt <- updateTime timeRef newTime
+ let dtSecs = fromIntegral dt / 100
+ return dtSecs
+
+initGraphs :: IO ()
+initGraphs = do
+ -- Initialise SDL
+ SDL.init [InitVideo]
+
+ -- Create window
+ screen <- setVideoMode width height 16 [SWSurface]
+ setCaption "Test" ""
+
+display :: (Double, Double) -> IO()
+display (boxY0,boxY) = do
+ -- Obtain surface
+ screen <- getVideoSurface
+
+ -- Paint screen green
+ let format = surfaceGetPixelFormat screen
+ green <- mapRGB format 0 0xFF 0
+ fillRect screen Nothing green
+
+ -- Paint small red square, at an angle 'angle' with respect to the center
+ red <- mapRGB format 0xFF 0xFF 0
+ let x = fromIntegral $ (width - boxSide) `div` 2
+ y0 = round boxY0
+ y = round boxY
+ vLine screen x y0 y red
+
+ -- Double buffering
+ SDL.flip screen
+
+rising :: Double -> Double -> SF () (Double, Double)
+rising y0 v0 = proc () -> do
+ y <- (y0+) ^<< integral -< v0
+ returnA -< (y0, y)
+
+fire :: Double -> Double -> SF () (Double, Double)
+fire y vy = switch (rising y vy >>> (Yampa.identity &&& hitCeiling))
+ (\_ -> fire y vy)
+
+hitCeiling :: SF (Double, Double) (Yampa.Event (Double, Double))
+hitCeiling = arr (\(y0,y) ->
+ let boxTop = y
+ in if boxTop < 0
+ then Yampa.Event (y0, y)
+ else Yampa.NoEvent)
+
+boxSide :: Int
+boxSide = 30
diff --git a/Experiments/circling-boxes/Main.hs b/Experiments/circling-boxes/Main.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/circling-boxes/Main.hs
@@ -0,0 +1,77 @@
+{-# LANGUAGE Arrows #-}
+import Graphics.UI.SDL as SDL
+import FRP.Yampa as Yampa
+import Data.IORef
+
+width = 640
+height = 480
+
+main = do
+ timeRef <- newIORef (0 :: Int)
+ reactimate initGraphs
+ (\_ -> do
+ dtSecs <- yampaSDLTimeSense timeRef
+ return (dtSecs, Nothing))
+ (\_ e -> display e >> return False)
+ inCirclesL
+
+-- | Updates the time in an IO Ref and returns the time difference
+updateTime :: IORef Int -> Int -> IO Int
+updateTime timeRef newTime = do
+ previousTime <- readIORef timeRef
+ writeIORef timeRef newTime
+ return (newTime - previousTime)
+
+yampaSDLTimeSense :: IORef Int -> IO Yampa.DTime
+yampaSDLTimeSense timeRef = do
+ -- Get time passed since SDL init
+ newTime <- fmap fromIntegral SDL.getTicks
+
+ -- Obtain time difference
+ dt <- updateTime timeRef newTime
+ let dtSecs = fromIntegral dt / 100
+ return dtSecs
+
+initGraphs :: IO ()
+initGraphs = do
+ -- Initialise SDL
+ SDL.init [InitVideo]
+
+ -- Create window
+ screen <- setVideoMode width height 16 [SWSurface]
+ setCaption "Test" ""
+
+display :: [(Double,Double)] -> IO()
+display xs = do
+ -- Obtain surface
+ screen <- getVideoSurface
+
+ -- Paint screen green
+ let format = surfaceGetPixelFormat screen
+ green <- mapRGB format 0 0xFF 0
+ fillRect screen Nothing green
+
+ -- Paint small red square, at an angle 'angle' with respect to the center
+ red <- mapRGB format 0xFF 0 0
+ let side = 10
+ let paintSquare (x,y) =
+ fillRect screen (Just (Rect (round x) (round y) side side)) red
+
+ mapM_ paintSquare xs
+
+ -- Double buffering
+ SDL.flip screen
+
+
+inCirclesL :: SF () [(Double, Double)]
+inCirclesL = parB [ inCircles (100, 100)
+ , inCircles (200, 200)
+ ]
+
+inCircles :: (Double, Double) -> SF () (Double, Double)
+inCircles (baseX, baseY) = proc () -> do
+ t <- (/5) ^<< localTime -< ()
+ let radius = 30
+ x = baseX + (cos t * radius)
+ y = baseY + (sin t * radius)
+ returnA -< (x,y)
diff --git a/Experiments/collisions/Constants.hs b/Experiments/collisions/Constants.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/collisions/Constants.hs
@@ -0,0 +1,48 @@
+module Constants where
+
+import Data.Int
+import Data.Word
+import Graphics.UI.SDL as SDL
+
+width :: Double
+width = 640
+height :: Double
+height = 480
+
+gameWidth :: Double
+gameWidth = width
+
+gameHeight :: Double
+gameHeight = height
+
+-- Energy transmission between objects in collisions
+velTrans :: Double
+velTrans = 0.98
+
+-- Max speed
+maxVNorm :: Double
+maxVNorm = 50000
+
+gravity :: (Double, Double)
+gravity = (0, -1000.8)
+
+-- Delays
+ballWidth, ballHeight :: Double
+ballWidth = 30
+ballHeight = 30
+
+ballMargin :: Double
+ballMargin = 3
+
+ballSize :: Int16
+ballSize = 30
+
+-- Colors
+fontColor :: SDL.Color
+fontColor = SDL.Color 228 228 228
+
+ballColor :: Word32
+ballColor = 0xCC0011FF
+
+velColor :: Word32
+velColor = 0xCCBBFFFF
diff --git a/Experiments/collisions/Control/Extra/Monad.hs b/Experiments/collisions/Control/Extra/Monad.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/collisions/Control/Extra/Monad.hs
@@ -0,0 +1,19 @@
+module Control.Extra.Monad where
+
+import Control.Monad
+
+whileLoopM :: Monad m => m a -> (a -> Bool) -> (a -> m ()) -> m ()
+whileLoopM val cond act = r'
+ where r' = do v <- val
+ when (cond v) $ do
+ act v
+ whileLoopM val cond act
+
+foldLoopM :: Monad m => a -> m b -> (b -> Bool) -> (a -> b -> m a) -> m a
+foldLoopM val sense cond act = r'
+ where r' = do s <- sense
+ if cond s
+ then do
+ val' <- act val s
+ foldLoopM val' sense cond act
+ else return val
diff --git a/Experiments/collisions/Data/Extra/Num.hs b/Experiments/collisions/Data/Extra/Num.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/collisions/Data/Extra/Num.hs
@@ -0,0 +1,20 @@
+module Data.Extra.Num where
+
+ensurePos :: (Eq a, Num a) => a -> a
+ensurePos e = if signum e == (-1) then negate e else e
+
+ensureNeg :: (Eq a, Num a) => a -> a
+ensureNeg e = if signum e == 1 then negate e else e
+
+class Similar a where
+ sigma :: a -- margin of error
+
+instance Similar Float where
+ sigma = 0.01
+
+instance Similar Double where
+ sigma = 0.01
+
+(=~) :: (Num a, Ord a, Similar a) => a -> a -> Bool
+x =~ y = abs (x - y) < sigma
+
diff --git a/Experiments/collisions/Data/Extra/VectorSpace.hs b/Experiments/collisions/Data/Extra/VectorSpace.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/collisions/Data/Extra/VectorSpace.hs
@@ -0,0 +1,6 @@
+module Data.Extra.VectorSpace where
+
+import FRP.Yampa.VectorSpace
+
+limitNorm :: (Ord s, VectorSpace v s) => v -> s -> v
+limitNorm v mn = if norm v > mn then mn *^ normalize v else v
diff --git a/Experiments/collisions/Data/IdentityList.hs b/Experiments/collisions/Data/IdentityList.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/collisions/Data/IdentityList.hs
@@ -0,0 +1,190 @@
+{-
+******************************************************************************
+* I N V A D E R S *
+* *
+* Module: IdentityList *
+* Purpose: Association list with automatic key assignment and *
+* identity-preserving map and filter operations. *
+* Author: Henrik Nilsson *
+* *
+* Copyright (c) Yale University, 2003 *
+* *
+******************************************************************************
+-}
+
+module Data.IdentityList (
+ ILKey, -- Identity-list key type
+ IL, -- Identity-list, abstract. Instance of functor.
+ emptyIL, -- :: IL a
+ insertIL_, -- :: a -> IL a -> IL a
+ insertIL, -- :: a -> IL a -> (ILKey, IL a)
+ listToIL, -- :: [a] -> IL a
+ keysIL, -- :: IL a -> [ILKey]
+ elemsIL, -- :: IL a -> [a]
+ assocsIL, -- :: IL a -> [(ILKey, a)]
+ deleteIL, -- :: ILKey -> IL a -> IL a
+ updateIL, -- :: ILKey -> a -> IL a -> IL a
+ updateILWith, -- :: ILKey -> (a -> a) -> IL a -> IL a
+ mapIL, -- :: ((ILKey, a) -> b) -> IL a -> IL b
+ filterIL, -- :: ((ILKey, a) -> Bool) -> IL a -> IL a
+ mapFilterIL, -- :: ((ILKey, a) -> Maybe b) -> IL a -> IL b
+ lookupIL, -- :: ILKey -> IL a -> Maybe a
+ findIL, -- :: ((ILKey, a) -> Bool) -> IL a -> Maybe a
+ mapFindIL, -- :: ((ILKey, a) -> Maybe b) -> IL a -> Maybe b
+ findAllIL, -- :: ((ILKey, a) -> Bool) -> IL a -> [a]
+ mapFindAllIL, -- :: ((ILKey, a) -> Maybe b) -> IL a -> [b]
+ ilSeq,
+) where
+
+import Data.List (find)
+import Data.Foldable
+
+
+------------------------------------------------------------------------------
+-- Data type definitions
+------------------------------------------------------------------------------
+
+type ILKey = Int
+
+-- Invariants:
+-- * Sorted in descending key order. (We don't worry about
+-- key wrap around).
+-- * Keys are NOT reused
+data IL a = IL { ilNextKey :: ILKey, ilAssocs :: [(ILKey, a)] }
+
+
+instance Foldable IL where
+ foldMap f = foldMap f . map snd . ilAssocs
+------------------------------------------------------------------------------
+-- Class instances
+------------------------------------------------------------------------------
+
+instance Functor IL where
+ fmap f (IL {ilNextKey = nk, ilAssocs = kas}) =
+ IL {ilNextKey = nk, ilAssocs = [ (i, f a) | (i, a) <- kas ]}
+
+
+------------------------------------------------------------------------------
+-- Constructors
+------------------------------------------------------------------------------
+
+emptyIL :: IL a
+emptyIL = IL {ilNextKey = 0, ilAssocs = []}
+
+
+insertIL_ :: a -> IL a -> IL a
+insertIL_ a il = snd (insertIL a il)
+
+
+insertIL :: a -> IL a -> (ILKey, IL a)
+insertIL a (IL {ilNextKey = k, ilAssocs = kas}) = (k, il') where
+ il' = IL {ilNextKey = k + 1, ilAssocs = (k, a) : kas}
+
+
+listToIL :: [a] -> IL a
+listToIL as = IL {ilNextKey = length as,
+ ilAssocs = reverse (zip [0..] as)} -- Maintain invariant!
+
+
+------------------------------------------------------------------------------
+-- Additional selectors
+------------------------------------------------------------------------------
+
+assocsIL :: IL a -> [(ILKey, a)]
+assocsIL = ilAssocs
+
+
+keysIL :: IL a -> [ILKey]
+keysIL = map fst . ilAssocs
+
+
+elemsIL :: IL a -> [a]
+elemsIL = map snd . ilAssocs
+
+
+------------------------------------------------------------------------------
+-- Mutators
+------------------------------------------------------------------------------
+
+deleteIL :: ILKey -> IL a -> IL a
+deleteIL k (IL {ilNextKey = nk, ilAssocs = kas}) =
+ IL {ilNextKey = nk, ilAssocs = deleteHlp kas}
+ where
+ deleteHlp [] = []
+ deleteHlp kakas@(ka@(k', _) : kas) | k > k' = kakas
+ | k == k' = kas
+ | otherwise = ka : deleteHlp kas
+
+updateIL :: ILKey -> a -> IL a -> IL a
+updateIL k v l = updateILWith k (const v) l
+
+updateILWith :: ILKey -> (a -> a) -> IL a -> IL a
+updateILWith k f l = mapIL g l
+ where g (k',v') | k == k' = f v'
+ | otherwise = v'
+
+------------------------------------------------------------------------------
+-- Filter and map operations
+------------------------------------------------------------------------------
+
+-- These are "identity-preserving", i.e. the key associated with an element
+-- in the result is the same as the key of the element from which the
+-- result element was derived.
+
+mapIL :: ((ILKey, a) -> b) -> IL a -> IL b
+mapIL f (IL {ilNextKey = nk, ilAssocs = kas}) =
+ IL {ilNextKey = nk, ilAssocs = [(k, f ka) | ka@(k,_) <- kas]}
+
+
+filterIL :: ((ILKey, a) -> Bool) -> IL a -> IL a
+filterIL p (IL {ilNextKey = nk, ilAssocs = kas}) =
+ IL {ilNextKey = nk, ilAssocs = filter p kas}
+
+
+mapFilterIL :: ((ILKey, a) -> Maybe b) -> IL a -> IL b
+mapFilterIL p (IL {ilNextKey = nk, ilAssocs = kas}) =
+ IL {
+ ilNextKey = nk,
+ ilAssocs = [(k, b) | ka@(k, _) <- kas, Just b <- [p ka]]
+ }
+
+
+------------------------------------------------------------------------------
+-- Lookup operations
+------------------------------------------------------------------------------
+
+lookupIL :: ILKey -> IL a -> Maybe a
+lookupIL k il = lookup k (ilAssocs il)
+
+
+findIL :: ((ILKey, a) -> Bool) -> IL a -> Maybe a
+findIL p (IL {ilAssocs = kas}) = findHlp kas
+ where
+ findHlp [] = Nothing
+ findHlp (ka@(_, a) : kas) = if p ka then Just a else findHlp kas
+
+
+mapFindIL :: ((ILKey, a) -> Maybe b) -> IL a -> Maybe b
+mapFindIL p (IL {ilAssocs = kas}) = mapFindHlp kas
+ where
+ mapFindHlp [] = Nothing
+ mapFindHlp (ka : kas) = case p ka of
+ Nothing -> mapFindHlp kas
+ jb@(Just _) -> jb
+
+
+findAllIL :: ((ILKey, a) -> Bool) -> IL a -> [a]
+findAllIL p (IL {ilAssocs = kas}) = [ a | ka@(_, a) <- kas, p ka ]
+
+
+mapFindAllIL:: ((ILKey, a) -> Maybe b) -> IL a -> [b]
+mapFindAllIL p (IL {ilAssocs = kas}) = [ b | ka <- kas, Just b <- [p ka] ]
+
+ilSeq :: IL a -> IL a
+ilSeq il = mapSeq (ilAssocs il) `seq` il
+
+mapSeq :: [a] -> [a]
+mapSeq x = x `seq` mapSeq' x
+mapSeq' [] = []
+mapSeq' (a:as) = a `seq` mapSeq as
+
diff --git a/Experiments/collisions/Debug.hs b/Experiments/collisions/Debug.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/collisions/Debug.hs
@@ -0,0 +1,8 @@
+module Debug where
+
+import Control.Monad (when, void)
+
+import Constants
+
+debug :: Bool -> String -> IO ()
+debug b msg = when b $ putStrLn msg
diff --git a/Experiments/collisions/Display.hs b/Experiments/collisions/Display.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/collisions/Display.hs
@@ -0,0 +1,117 @@
+module Display where
+
+import Control.Arrow ((***))
+import Control.Monad
+import FRP.Yampa.VectorSpace
+import Graphics.UI.SDL as SDL
+import qualified Graphics.UI.SDL.Primitives as SDLP
+import qualified Graphics.UI.SDL.TTF as TTF
+import Text.Printf
+
+import Constants
+import GameState
+import Objects
+import Resources
+
+-- | Ad-hoc resource loading
+-- This function is ad-hoc in two senses: first, because it
+-- has the paths to the files hard-coded inside. And second,
+-- because it loads the specific resources that are needed,
+-- so it's not a general, parameterised, scalable solution.
+--
+loadResources :: IO Resources
+loadResources = do
+ -- Font initialization
+ _ <- TTF.init
+
+ -- Load the fonts we need
+ let gameFont = "data/lacuna.ttf"
+ font <- TTF.openFont gameFont 32 -- 32: fixed size?
+ let myFont = font
+
+ -- Load the fonts we need
+ let gameFont = "data/lacuna.ttf"
+ font2 <- TTF.openFont gameFont 8 -- 32: fixed size?
+ let myFont2 = font2
+
+ -- Return all resources (just the font)
+ return $ Resources myFont myFont2
+
+initializeDisplay :: IO ()
+initializeDisplay =
+ -- Initialise SDL
+ SDL.init [InitEverything]
+
+initGraphs :: Resources -> IO ()
+initGraphs _res = do
+ screen <- SDL.setVideoMode (round width) (round height) 32 [SWSurface]
+ SDL.setCaption "Voldemort" ""
+
+ -- Important if we want the keyboard to work right (I don't know
+ -- how to make it work otherwise)
+ SDL.enableUnicode True
+
+ -- Hide mouse
+ SDL.showCursor True
+
+ return ()
+
+render :: Resources -> GameState -> IO()
+render resources shownState = do
+ -- Obtain surface
+ screen <- getVideoSurface
+
+ let format = surfaceGetPixelFormat screen
+ bgColor <- mapRGB format 0x37 0x16 0xB4
+ fillRect screen Nothing bgColor
+
+ displayInfo screen resources (gameInfo shownState)
+
+ mapM_ (paintObject screen resources ) $ gameObjects shownState
+
+ -- Double buffering
+ SDL.flip screen
+
+-- * Painting functions
+displayInfo :: Surface -> Resources -> GameInfo -> IO()
+displayInfo screen resources over =
+ printAlignRight screen resources
+ ("Time: " ++ printf "%.3f" (gameTime over)) (10,50)
+
+paintObject :: Surface -> Resources -> Object -> IO ()
+paintObject screen resources object =
+ case objectKind object of
+ (Side {}) -> return ()
+ _ -> do
+ let (px,py) = (\(u,v) -> (u, gameHeight - v)) (objectPos object)
+ let (x,y) = (round *** round) (px,py)
+ (vx,vy) = objectVel object
+ (x',y') = (round *** round) ((px,py) ^+^ (0.1 *^ (vx, -vy)))
+ _ <- SDLP.filledCircle screen x y ballSize (SDL.Pixel ballColor)
+ _ <- SDLP.line screen x y x' y' (SDL.Pixel velColor)
+
+ -- Print position
+ let font = miniFont resources
+ message <- TTF.renderTextSolid font (show $ (round *** round) (objectPos object)) fontColor
+ let w = SDL.surfaceGetWidth message
+ h = SDL.surfaceGetHeight message
+ (x'',y'') = (round *** round) (px,py)
+ rect = SDL.Rect (x''+30) (y''-30) w h
+ SDL.blitSurface message Nothing screen (Just rect)
+ return ()
+
+-- * Render text with alignment
+printAlignRight :: Surface -> Resources -> String -> (Int, Int) -> IO ()
+printAlignRight screen resources msg (x,y) = void $ do
+ let font = resFont resources
+ message <- TTF.renderTextSolid font msg fontColor
+ renderAlignRight screen message (x,y)
+
+-- * SDL Extensions
+renderAlignRight :: Surface -> Surface -> (Int, Int) -> IO ()
+renderAlignRight screen surface (x,y) = void $ do
+ let rightMargin = SDL.surfaceGetWidth screen
+ w = SDL.surfaceGetWidth surface
+ h = SDL.surfaceGetHeight surface
+ rect = SDL.Rect (rightMargin - x - w) y w h
+ SDL.blitSurface surface Nothing screen (Just rect)
diff --git a/Experiments/collisions/Game.hs b/Experiments/collisions/Game.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/collisions/Game.hs
@@ -0,0 +1,250 @@
+{-# LANGUAGE Arrows #-}
+-- | This module defines the game as a big Signal Function that transforms a
+-- Signal carrying a Input 'Controller' information into a Signal carrying
+-- 'GameState'.
+--
+-- There is no randomness in the game, the only input is the user's.
+-- 'Controller' is an abstract representation of a basic input device with
+-- position information and a /fire/ button.
+--
+-- The output is defined in 'GameState', and consists of basic information
+-- (points, current level, etc.) and a universe of objects.
+--
+-- Objects are represented as Signal Functions as well ('ObjectSF'). This
+-- allows them to react to user input and change with time. Each object is
+-- responsible for itself, but it cannot affect others: objects can watch
+-- others, depend on others and react to them, but they cannot /send a
+-- message/ or eliminate other objects. However, if you would like to
+-- dynamically introduce new elements in the game (for instance, falling
+-- powerups that the player must collect before they hit the ground) then it
+-- might be a good idea to allow objects not only to /kill themselves/ but
+-- also to spawn new object.
+--
+-- This module contains two sections:
+--
+-- - A collection of gameplay SFs, which control the core game loop, carry
+-- out collision detection, , etc.
+--
+-- - One SF per game object. These define the elements in the game universe,
+-- which can observe other elements, depend on user input, on previous
+-- collisions, etc.
+--
+-- You may want to read the basic definition of 'GameState', 'Controller' and
+-- 'ObjectSF' before you attempt to go through this module.
+--
+module Game (wholeGame) where
+
+-- External imports
+import FRP.Yampa
+
+-- General-purpose internal imports
+import Data.Extra.VectorSpace
+import Data.IdentityList
+import Physics.TwoDimensions.Collisions
+import Physics.TwoDimensions.Dimensions
+import Physics.TwoDimensions.GameCollisions
+import Physics.TwoDimensions.Shapes
+
+-- Internal iports
+import Constants
+import GameState
+import Input
+import Objects
+import ObjectSF
+
+-- * General state transitions
+
+-- | Run the game that the player can lose at ('canLose'), until ('switch')
+-- there are no more levels ('outOfLevels'), in which case the player has won
+-- ('wonGame').
+wholeGame :: SF Controller GameState
+wholeGame = gamePlay initialObjects >>> composeGameState
+ where composeGameState :: SF (Objects, Time) GameState
+ composeGameState = arr (second GameInfo >>> uncurry GameState)
+
+-- ** Game with partial state information
+
+-- | Given an initial list of objects, it runs the game, presenting the output
+-- from those objects at all times, notifying any time the ball hits the floor,
+-- and and of any additional points made.
+--
+-- This works as a game loop with a post-processing step. It uses
+-- a well-defined initial accumulator and a traditional feedback
+-- loop.
+--
+-- The internal accumulator holds the last known collisions (discarded at every
+-- iteration).
+
+gamePlay :: ObjectSFs -> SF Controller (Objects, Time)
+gamePlay objs = loopPre [] $
+ -- Process physical movement and detect new collisions
+ proc (i) -> do
+ -- Adapt Input
+ let oi = (uncurry ObjectInput) i
+
+ -- Step
+ -- Each obj processes its movement forward
+ ol <- ilSeq ^<< parB objs -< oi
+ let cs' = detectCollisions ol
+
+ -- Output
+ elems <- arr elemsIL -< ol
+ tLeft <- time -< ()
+ returnA -< ((elems, tLeft), cs')
+
+-- * Game objects
+--
+-- | Objects initially present: the walls, the ball, the paddle and the blocks.
+initialObjects :: ObjectSFs
+initialObjects = listToIL $
+ [ objSideRight
+ , objSideTop
+ , objSideLeft
+ , objSideBottom
+ ]
+ ++ objEnemies
+
+-- *** Enemy
+objEnemies :: [ObjectSF]
+objEnemies =
+ [ bouncingBall "enemy1" (300, 300) (360, -350)
+ , bouncingBall "enemy2" (500, 300) (-330, -280)
+ , bouncingBall "enemy3" (200, 100) (-300, -250)
+ , bouncingBall "enemy4" (100, 200) (-200, -150)
+ ]
+-- objEnemies _ =
+-- [ bouncingBall "enemy1" (300, 300) (360, -350)
+-- , bouncingBall "enemy2" (500, 300) (-300, -250)
+-- , bouncingBall "enemy3" (200, 100) (-300, -250)
+-- , bouncingBall "enemy4" (100, 200) (-200, -150)
+-- , bouncingBall "enemy5" (200, 200) (-300, -150)
+-- , bouncingBall "enemy6" (400, 400) (200, 200)
+-- ]
+
+-- *** Ball
+
+-- A bouncing ball moves freely until there is a collision, then bounces and
+-- goes on and on.
+--
+-- This SF needs an initial position and velocity. Every time
+-- there is a bounce, it takes a snapshot of the point of
+-- collision and corrected velocity, and starts again.
+--
+bouncingBall :: String -> Pos2D -> Vel2D -> ObjectSF
+bouncingBall bid p0 v0 =
+ switch progressAndBounce
+ (uncurry (bouncingBall bid)) -- Somehow it would be clearer like this:
+ -- \(p', v') -> bouncingBall p' v')
+ where
+
+ -- Calculate the future tentative position, and
+ -- bounce if necessary.
+ --
+ -- The ballBounce needs the ball SF' input (which has knowledge of
+ -- collisions), so we carry it parallely to the tentative new positions,
+ -- and then use it to detect when it's time to bounce
+
+ -- ========================== ============================
+ -- -==--------------------->==--->==- ------------------->==
+ -- / == == == \ / ==
+ -- -- == == == X ==
+ -- \ == == == / \ ==
+ -- -==----> freeBall' ----->==--->==--------> ballBounce -->==
+ -- ========================== ============================
+ progressAndBounce = (arr id &&& freeBall') >>> (arr snd &&& ballBounce bid)
+
+ -- Position of the ball, starting from p0 with velicity v0, since the
+ -- time of last switching (or being fired, whatever happened last)
+ -- provided that no obstacles are encountered.
+ freeBall' = freeBall bid p0 v0
+
+-- | Detect if the ball must bounce and, if so, take a snapshot of the object's
+-- current position and velocity.
+--
+-- NOTE: To avoid infinite loops when switching, the initial input is discarded
+-- and never causes a bounce. This works in this game and in this particular
+-- case because the ball never-ever bounces immediately as fired from the
+-- paddle. This might not be true if a block is extremely close, if you add
+-- flying enemies to the game, etc.
+ballBounce :: String -> SF (ObjectInput, Object) (Event (Pos2D, Vel2D))
+ballBounce bid = noEvent --> ballBounce' bid
+
+-- | Detect if the ball must bounce and, if so, take a snapshot of the object's
+-- current position and velocity.
+--
+-- This does the core of the work, and does not ignore the initial input.
+--
+-- It proceeds by detecting whether any collision affects
+-- the ball's velocity, and outputs a snapshot of the object
+-- position and the corrected velocity if necessary.
+ballBounce' :: String -> SF (ObjectInput, Object) (Event (Pos2D, Vel2D))
+ballBounce' bid = proc (ObjectInput ci cs, o) -> do
+ -- HN 2014-09-07: With the present strategy, need to be able to
+ -- detect an event directly after
+ -- ev <- edgeJust -< changedVelocity "ball" cs
+ let ev = maybeToEvent (changedVelocity bid cs)
+ returnA -< fmap (\v -> (objectPos o, v)) ev
+
+-- | Position of the ball, starting from p0 with velicity v0, since the time of
+-- last switching (that is, collision, or the beginning of time --being fired
+-- from the paddle-- if never switched before), provided that no obstacles are
+-- encountered.
+freeBall :: String -> Pos2D -> Vel2D -> ObjectSF
+freeBall name p0 v0 = proc (ObjectInput ci cs) -> do
+
+ -- Any free moving object behaves like this (but with
+ -- acceleration. This should be in some FRP.NewtonianPhysics
+ -- module)
+ v <- (v0 ^+^) ^<< integral -< gravity
+ p <- (p0 ^+^) ^<< integral -< v
+
+ returnA -< Object { objectName = name
+ , objectKind = Ball ballWidth
+ , objectPos = p
+ , objectVel = v
+ , canCauseCollisions = True
+ , collisionEnergy = velTrans
+ }
+
+-- *** Walls
+
+-- | Walls. Each wall has a side and a position.
+--
+-- NOTE: They are considered game objects instead of having special treatment.
+-- The function that turns walls into 'Shape's for collision detection
+-- determines how big they really are. In particular, this has implications in
+-- ball-through-paper effects (ball going through objects, potentially never
+-- coming back), which can be seen if the FPS suddently drops due to CPU load
+-- (for instance, if a really major Garbage Collection kicks in. One potential
+-- optimisation is to trigger these with every SF iteration or every rendering,
+-- to decrease the workload and thus the likelyhood of BTP effects.
+objSideRight :: ObjectSF
+objSideRight = objWall "rightWall" RightSide (gameWidth, 0)
+
+-- | See 'objSideRight'.
+objSideLeft :: ObjectSF
+objSideLeft = objWall "leftWall" LeftSide (0, 0)
+
+-- | See 'objSideRight'.
+objSideTop :: ObjectSF
+objSideTop = objWall "topWall" TopSide (0, 0)
+
+-- | See 'objSideRight'.
+objSideBottom :: ObjectSF
+objSideBottom = objWall "bottomWall" BottomSide (0, gameHeight)
+
+-- | Generic wall builder, given a name, a side and its base
+-- position.
+objWall :: ObjectName -> Side -> Pos2D -> ObjectSF
+objWall name side pos = arr $ \(ObjectInput ci cs) ->
+ Object { objectName = name
+ , objectKind = Side side
+ , objectPos = pos
+ , objectVel = (0,0)
+ , canCauseCollisions = False
+ , collisionEnergy = 0
+ }
+
+-- * Auxiliary FRP stuff
+maybeToEvent :: Maybe a -> Event a
+maybeToEvent = maybe noEvent Event
diff --git a/Experiments/collisions/GameState.hs b/Experiments/collisions/GameState.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/collisions/GameState.hs
@@ -0,0 +1,36 @@
+-- | The state of the game during execution. It has two
+-- parts: general info (level, points, etc.) and
+-- the actual gameplay info (objects).
+--
+-- Because the game is always in some running state
+-- (there are no menus, etc.) we assume that there's
+-- always some gameplay info, even though it can be
+-- empty.
+module GameState where
+
+-- import FRP.Yampa as Yampa
+
+import Debug.Trace
+import Objects
+import FRP.Yampa (Time)
+
+-- | The running state is given by a bunch of 'Objects' and the current general
+-- 'GameInfo'. The latter contains info regarding the current level, the number
+-- of points, etc.
+--
+-- Different parts of the game deal with these data structures. It is
+-- therefore convenient to group them in subtrees, even if there's no
+-- substantial difference betweem them.
+data GameState = GameState
+ { gameObjects :: !Objects
+ , gameInfo :: !GameInfo
+ }
+
+-- | Initial (default) game state.
+neutralGameState :: GameState
+neutralGameState = GameState
+ { gameObjects = []
+ , gameInfo = GameInfo 0
+ }
+
+data GameInfo = GameInfo { gameTime :: Time }
diff --git a/Experiments/collisions/Graphics/UI/Extra/SDL.hs b/Experiments/collisions/Graphics/UI/Extra/SDL.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/collisions/Graphics/UI/Extra/SDL.hs
@@ -0,0 +1,40 @@
+module Graphics.UI.Extra.SDL where
+
+import Data.IORef
+import Data.Maybe (isNothing)
+import Graphics.UI.SDL as SDL
+
+-- Auxiliary SDL stuff
+isEmptyEvent :: Event -> Bool
+isEmptyEvent SDL.NoEvent = True
+isEmptyEvent _ = False
+
+initializeTimeRef :: IO (IORef Int)
+initializeTimeRef = do
+ -- Weird shit I have to do to get accurate time!
+ timeRef <- newIORef (0 :: Int)
+ _ <- senseTimeRef timeRef
+ _ <- senseTimeRef timeRef
+ _ <- senseTimeRef timeRef
+ _ <- senseTimeRef timeRef
+
+ return timeRef
+
+senseTimeRef :: IORef Int -> IO Int
+senseTimeRef timeRef = do
+ -- Get time passed since SDL init
+ newTime <- fmap fromIntegral SDL.getTicks
+
+ -- Obtain time difference
+ dt <- updateTime timeRef newTime
+ return dt
+
+-- | Updates the time in an IO Ref and returns the time difference
+updateTime :: IORef Int -> Int -> IO Int
+updateTime timeRef newTime = do
+ previousTime <- readIORef timeRef
+ writeIORef timeRef newTime
+ return (newTime - previousTime)
+
+milisecsToSecs :: Int -> Double
+milisecsToSecs m = fromIntegral m / 1000
diff --git a/Experiments/collisions/Input.hs b/Experiments/collisions/Input.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/collisions/Input.hs
@@ -0,0 +1,109 @@
+-- | Defines an abstraction for the game controller and the functions to read
+-- it.
+--
+-- Lower-level devices replicate the higher-level API, and should accomodate to
+-- it. Each device should:
+--
+-- - Upon initialisation, return any necessary information to poll it again.
+--
+-- - Update the controller with its own values upon sensing.
+--
+-- In this case, we only have one: mouse/keyboard combination.
+--
+module Input where
+
+-- External imports
+import Data.IORef
+import Graphics.UI.SDL as SDL
+
+-- Internal imports
+import Control.Extra.Monad
+import Graphics.UI.Extra.SDL
+
+-- * Game controller
+
+-- | Controller info at any given point.
+data Controller = Controller
+ { controllerPos :: (Double, Double)
+ , controllerClick :: Bool
+ , controllerPause :: Bool
+ , controllerExit :: Bool
+ , controllerFast :: Bool
+ , controllerSlow :: Bool
+ , controllerSuperSlow :: Bool
+ , controllerFullscreen :: Bool
+ }
+
+-- | Controller info at any given point, plus a pointer
+-- to poll the main device again. This is safe,
+-- since there is only one writer at a time (the device itself).
+newtype ControllerRef =
+ ControllerRef { controllerData :: (IORef Controller, Controller -> IO Controller) }
+
+-- * General API
+
+-- | Initialize the available input devices. This operation
+-- returns a reference to a controller, which enables
+-- getting its state as many times as necessary. It does
+-- not provide any information about its nature, abilities, etc.
+initializeInputDevices :: IO ControllerRef
+initializeInputDevices = do
+ nr <- newIORef defaultInfo
+ return $ ControllerRef (nr, sdlGetController)
+ where defaultInfo = Controller (0,0) False False False False False False False
+
+-- | Sense from the controller, providing its current
+-- state. This should return a new Controller state
+-- if available, or the last one there was.
+--
+-- It is assumed that the sensing function is always
+-- callable, and that it knows how to update the
+-- Controller info if necessary.
+senseInput :: ControllerRef -> IO Controller
+senseInput (ControllerRef (cref, sensor)) =
+ modifyIORefIO cref sensor
+
+type ControllerDev = IO (Maybe (Controller -> IO Controller))
+
+-- * SDL API (mid-level)
+
+-- ** Sensing
+
+-- | Sense the SDL keyboard and mouse and update
+-- the controller. It only senses the mouse position,
+-- the primary mouse button, and the p key to pause
+-- the game.
+--
+-- We need a non-blocking controller-polling function.
+-- TODO: Check http://gameprogrammer.com/fastevents/fastevents1.html
+sdlGetController :: Controller -> IO Controller
+sdlGetController info =
+ foldLoopM info pollEvent (not.isEmptyEvent) ((return .) . handleEvent)
+
+handleEvent :: Controller -> SDL.Event -> Controller
+handleEvent c e =
+ case e of
+ MouseMotion x y _ _ -> c { controllerPos = (fromIntegral x, fromIntegral y)}
+ MouseButtonDown _ _ ButtonLeft -> c { controllerClick = True }
+ MouseButtonUp _ _ ButtonLeft -> c { controllerClick = False}
+ KeyUp (Keysym { symKey = SDLK_p }) -> c { controllerPause = not (controllerPause c) }
+ KeyUp (Keysym { symKey = SDLK_f }) -> c { controllerFullscreen = not (controllerFullscreen c) }
+ KeyDown (Keysym { symKey = SDLK_w }) -> c { controllerSuperSlow = True }
+ KeyUp (Keysym { symKey = SDLK_w }) -> c { controllerSuperSlow = False }
+ KeyDown (Keysym { symKey = SDLK_s }) -> c { controllerSlow = True }
+ KeyUp (Keysym { symKey = SDLK_s }) -> c { controllerSlow = False }
+ KeyDown (Keysym { symKey = SDLK_x }) -> c { controllerFast = True }
+ KeyUp (Keysym { symKey = SDLK_x }) -> c { controllerFast = False }
+ KeyDown (Keysym { symKey = SDLK_SPACE }) -> c { controllerClick = True }
+ KeyUp (Keysym { symKey = SDLK_SPACE }) -> c { controllerClick = False }
+ KeyDown (Keysym { symKey = SDLK_ESCAPE}) -> c { controllerExit = True }
+ _ -> c
+
+
+-- * Aux IOREf
+modifyIORefIO :: IORef a -> (a -> IO a) -> IO a
+modifyIORefIO ref modify = do
+ v <- readIORef ref
+ new <- modify v
+ writeIORef ref new
+ return new
diff --git a/Experiments/collisions/Main.hs b/Experiments/collisions/Main.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/collisions/Main.hs
@@ -0,0 +1,47 @@
+import Control.Applicative
+import Control.Concurrent
+import Control.Monad
+import Control.Monad.IfElse
+import Data.IORef
+import Debug.Trace
+import FRP.Yampa as Yampa
+import Text.Printf
+
+import Game
+import Display
+import Input
+import Graphics.UI.Extra.SDL
+
+-- TODO: Use MaybeT or ErrorT to report errors
+main :: IO ()
+main = do
+
+ initializeDisplay
+
+ timeRef <- initializeTimeRef
+ controllerRef <- initializeInputDevices
+ res <- loadResources
+
+ initGraphs res
+ reactimate (senseInput controllerRef)
+ (\_ -> do
+ -- Get clock and new input
+ mInput <- senseInput controllerRef
+ dtSecs <- senseTime timeRef mInput
+ -- trace ("Time : " ++ printf "%.5f" dtSecs) $
+ return (if controllerPause mInput then 0 else dtSecs, Just mInput)
+ )
+ (\_ (e,c) -> do render res e
+ -- putStrLn "*********************************************"
+ return (controllerExit c)
+ )
+ (wholeGame &&& arr id)
+
+type MonadicT m a b = a -> m b
+
+senseTime :: IORef Int -> MonadicT IO Controller DTime
+senseTime timeRef = \mInput ->
+ let tt = if controllerSlow mInput then (/10) else id
+ tt1 = if controllerSuperSlow mInput then (/100) else tt
+ tt2 = if controllerFast mInput then (*10) else tt1
+ in (tt2 . milisecsToSecs) <$> senseTimeRef timeRef
diff --git a/Experiments/collisions/ObjectSF.hs b/Experiments/collisions/ObjectSF.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/collisions/ObjectSF.hs
@@ -0,0 +1,45 @@
+-- | Objects as signal functions.
+--
+-- Live objects in the game take user input and the game universe
+-- and define their state in terms of that. They can remember what
+-- happened (see Yampa's Arrow combinators, which hide continuations),
+-- change their behaviour (see switches in Yampa).
+module ObjectSF where
+
+import FRP.Yampa
+
+import Objects
+import Input
+import Data.IdentityList
+
+-- | Objects are defined as transformations that take 'ObjectInput' signals and
+-- return 'ObjectOutput' signals.
+type ObjectSF = SF ObjectInput Object
+
+-- | In order to determine its new output, an object needs to know the user's
+-- desires ('userInput'), whether there have been any collisions
+-- ('collisions').
+--
+-- The reason for depending on 'Collisions' is that objects may ``change''
+-- when hit (start moving in a different direction).
+data ObjectInput = ObjectInput
+ { userInput :: Controller
+ , collisions :: Collisions
+ }
+
+-- -- | What we can see about each live object at each time. It's a
+-- -- snapshot of the object.
+-- data ObjectOutput = ObjectOutput
+-- { outputObject :: Object -- ^ The object's state (position, shape, etc.).
+-- }
+
+-- | List of identifiable objects. Used to work with dynamic object
+-- collections.
+type ObjectSFs = IL ObjectSF
+
+-- extractObjects :: Functor f => SF (f ObjectOutput) (f Object)
+-- extractObjects = arr (fmap outputObject)
+--
+-- -- | A list of object outputs
+-- type ObjectOutputs = [ObjectOutput]
+--
diff --git a/Experiments/collisions/Objects.hs b/Experiments/collisions/Objects.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/collisions/Objects.hs
@@ -0,0 +1,65 @@
+{-# LANGUAGE TypeSynonymInstances #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+-- | Game objects and collisions.
+module Objects where
+
+import Control.Arrow ((***))
+import FRP.Yampa.VectorSpace
+
+import qualified Physics.TwoDimensions.Collisions as C
+import Physics.TwoDimensions.Dimensions
+import Physics.TwoDimensions.PhysicalObjects
+import qualified Physics.TwoDimensions.PhysicalObjects as PO
+import Physics.TwoDimensions.Shapes
+
+type Collision = C.Collision ObjectName
+type Collisions = C.Collisions ObjectName
+
+-- * Objects
+
+type Objects = [Object]
+type ObjectName = String
+
+-- | Objects have logical properties (ID, kind, dead, hit), shape properties
+-- (kind), physical properties (kind, pos, vel, acc) and collision properties
+-- (hit, 'canCauseCollisions', energy, displaced).
+data Object = Object { objectName :: !ObjectName
+ , objectKind :: !ObjectKind
+ , objectPos :: !Pos2D
+ , objectVel :: !Vel2D
+ , canCauseCollisions :: !Bool
+ , collisionEnergy :: !Double
+ }
+ deriving (Show)
+
+-- | The kind of object and any size properties.
+data ObjectKind = Ball Double -- radius
+ | Side Side
+ deriving (Show,Eq)
+
+-- Partial function. Object has size.
+objectTopLevelCorner :: Object -> Pos2D
+objectTopLevelCorner object = objectPos object ^-^ half (objectSize object)
+ where half = let h = (/2) in (h *** h)
+
+-- Partial function!
+objectSize :: Object -> Size2D
+objectSize object = case objectKind object of
+ (Ball r) -> let w = 2*r in (w, w)
+
+instance PhysicalObject Object String Shape where
+ physObjectPos = objectPos
+ physObjectVel = objectVel
+ physObjectElas = collisionEnergy
+ physObjectShape = objShape
+ physObjectCollides = canCauseCollisions
+ physObjectId = objectName
+ physObjectUpdatePos = \o p -> o { objectPos = p }
+ physObjectUpdateVel = \o v -> o { objectVel = v }
+
+objShape :: Object -> Shape
+objShape obj = case objectKind obj of
+ Ball r -> Circle p r
+ Side s -> SemiPlane p s
+ where p = objectPos obj
diff --git a/Experiments/collisions/Physics/TwoDimensions/Collisions.hs b/Experiments/collisions/Physics/TwoDimensions/Collisions.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/collisions/Physics/TwoDimensions/Collisions.hs
@@ -0,0 +1,143 @@
+{-# LANGUAGE FlexibleContexts #-}
+-- | A trivial collision subsystem.
+--
+-- Based on the physics module, it determines the side of collision
+-- between shapes.
+module Physics.TwoDimensions.Collisions where
+
+import Data.Extra.Num
+import Data.Maybe
+import FRP.Yampa.VectorSpace
+import Physics.TwoDimensions.Dimensions
+import Physics.TwoDimensions.PhysicalObjects
+import Physics.TwoDimensions.Shapes
+
+-- * Collision points
+data CollisionPoint = CollisionSide Side
+ | CollisionAngle Double
+
+-- | Calculates the collision side of a shape
+-- that collides against another.
+--
+-- PRE: the shapes do collide. Use 'overlapShape' to check.
+shapeCollisionPoint :: Shape -> Shape -> CollisionPoint
+shapeCollisionPoint (Circle p1 _) (Circle p2 _) =
+ -- | p1x =~ p2x && p1y > p2y = CollisionAngle (- pi / 2)
+ -- | p1x =~ p2x && p1y <= p2y = CollisionAngle (pi / 2)
+ -- | otherwise =
+ CollisionAngle angle
+ where (px,py) = p2 ^-^ p1
+ angle = atan2 py px
+shapeCollisionPoint (Circle _ _) (SemiPlane _ s2) = CollisionSide s2
+shapeCollisionPoint (SemiPlane _ s1) (Circle _ _ ) = CollisionSide (oppositeSide s1)
+shapeCollisionPoint (SemiPlane _ _) (SemiPlane _ s2) = CollisionSide s2
+-- * Collisions
+type Collisions k = [Collision k]
+
+-- | A collision is a list of objects that collided, plus their velocities as
+-- modified by the collision.
+--
+-- Take into account that the same object could take part in several
+-- simultaneous collitions, so these velocities should be added (per object).
+data Collision k = Collision
+ { collisionData :: [(k, Vel2D)] } -- ObjectId x Velocity
+ deriving Show
+
+-- | Detects a collision between one object and another.
+detectCollision :: (PhysicalObject o k Shape) => o -> o -> Maybe (Collision k)
+detectCollision obj1 obj2
+ | overlap obj1 obj2
+ = case (physObjectShape obj1, physObjectShape obj2) of
+ (Circle _ _, Circle _ _) ->
+ if vrn < 0
+ then Just response
+ else Nothing
+ _ -> Just response
+ | otherwise = Nothing
+
+ where response = collisionResponseObj obj1 obj2
+ colNormal = normalize (physObjectPos obj1 ^-^ physObjectPos obj2)
+ relativeP = physObjectPos obj1 ^-^ physObjectPos obj2
+ relativeV = physObjectVel obj1 ^-^ physObjectVel obj2
+ vrn = relativeV `dot` relativeP
+ -- NOTE: See Henrik's comment to the main game.
+
+overlap :: PhysicalObject o k Shape => o -> o -> Bool
+overlap obj1 obj2 =
+ overlapShape (physObjectShape obj1) (physObjectShape obj2)
+
+collisionPoint :: PhysicalObject o k Shape => o -> o -> CollisionPoint
+collisionPoint obj1 obj2 =
+ shapeCollisionPoint (physObjectShape obj1) (physObjectShape obj2)
+
+collisionResponseObj :: PhysicalObject o k Shape => o -> o -> Collision k
+collisionResponseObj o1 o2 = Collision $
+ map objectToCollision [(o1, collisionPt, o2), (o2, collisionPt', o1)]
+ where collisionPt = collisionPoint o1 o2
+ collisionPt' = collisionPoint o2 o1
+ objectToCollision (o,pt,o') =
+ (physObjectId o,
+ correctVel (physObjectPos o) (physObjectPos o')
+ (physObjectVel o) (physObjectVel o')
+ pt (physObjectElas o))
+
+correctVel :: Pos2D -> Pos2D -> Vel2D -> Vel2D -> CollisionPoint -> Double -> Vel2D
+-- Specialised cases: just more optimal execution
+correctVel _p1 _p2 v1 _ _ 0 = v1
+-- Collision against a wall
+correctVel _p1 _p2 (v1x,v1y) _ (CollisionSide TopSide) e = (e * v1x, e * ensurePos v1y)
+correctVel _p1 _p2 (v1x,v1y) _ (CollisionSide BottomSide) e = (e * v1x, e * ensureNeg v1y)
+correctVel _p1 _p2 (v1x,v1y) _ (CollisionSide LeftSide) e = (e * ensurePos v1x, e * v1y)
+correctVel _p1 _p2 (v1x,v1y) _ (CollisionSide RightSide) e = (e * ensureNeg v1x, e * v1y)
+-- General case
+correctVel p1 p2 (v1x,v1y) (v2x, v2y) (CollisionAngle _) e = (v1x, v1y) ^+^ ((e * j) *^ colNormal)
+ where colNormal = normalize (p1 ^-^ p2)
+ relativeV = (v1x,v1y) ^-^ (v2x,v2y)
+ vrn = relativeV `dot` colNormal
+ j = (-1) *^ vrn / (colNormal `dot` colNormal)
+
+-- | Return the new velocity as changed by the collection of collisions.
+--
+-- HN 2014-09-07: New interface to collision detection.
+--
+-- The assumption is that collision detection happens globally and that the
+-- changed velocity is figured out for each object involved in a collision
+-- based on the properties of all objects involved in any specific interaction.
+-- That may not be how it works now, but the interface means it could work
+-- that way. Even more physical might be to figure out the impulsive force
+-- acting on each object.
+--
+-- However, the whole collision infrastructure should be revisited.
+--
+-- - Statefulness ("edge") might make it more robust.
+--
+-- - Think through how collision events are going to be communicated
+-- to the objects themselves. Maybe an input event is the natural
+-- thing to do. Except then we have to be careful to avoid switching
+-- again immediately after one switch.
+--
+-- - Should try to avoid n^2 checks. Maybe some kind of quad-trees?
+-- Maybe spawning a stateful collision detector when two objects are
+-- getting close? Cf. the old tail-gating approach.
+-- - Maybe a collision should also carry the identity of the object
+-- one collieded with to facilitate impl. of "inCollisionWith".
+--
+changedVelocity :: Eq n => n -> Collisions n -> Maybe Vel2D
+changedVelocity name cs =
+ case concatMap (filter ((== name) . fst) . collisionData) cs of
+ [] -> Nothing
+ -- vs -> Just (foldl (^+^) (0,0) (map snd vs))
+ (_, v') : _ -> Just v'
+
+-- | True if the velocity of the object has been changed by any collision.
+inCollision :: Eq n => n -> Collisions n -> Bool
+inCollision name cs = isJust (changedVelocity name cs)
+
+-- | True if the two objects are colliding with one another.
+inCollisionWith :: Eq n => n -> n -> Collisions n -> Bool
+inCollisionWith nm1 nm2 cs = any both cs
+ where
+ both (Collision nmvs) =
+ any ((== nm1) . fst) nmvs
+ && any ((== nm2) . fst) nmvs
+
diff --git a/Experiments/collisions/Physics/TwoDimensions/Dimensions.hs b/Experiments/collisions/Physics/TwoDimensions/Dimensions.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/collisions/Physics/TwoDimensions/Dimensions.hs
@@ -0,0 +1,9 @@
+-- | Physical dimensions used all over the game. They are just type synonyms,
+-- but it's best to use meaningful names to make our type signatures more
+-- meaningful.
+module Physics.TwoDimensions.Dimensions where
+
+type Size2D = (Double, Double)
+type Pos2D = (Double, Double)
+type Vel2D = (Double, Double)
+type Acc2D = (Double, Double)
diff --git a/Experiments/collisions/Physics/TwoDimensions/GameCollisions.hs b/Experiments/collisions/Physics/TwoDimensions/GameCollisions.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/collisions/Physics/TwoDimensions/GameCollisions.hs
@@ -0,0 +1,59 @@
+{-# LANGUAGE FlexibleContexts #-}
+-- | A very rudimentary collision system.
+--
+-- It compares every pair of objects, trying to determine if there is a
+-- collision between the two of them.
+--
+-- NOTE: In order to minimize the number of comparisons, only moving objects
+-- are tested (against every game object). That's only 2 objects right now
+-- (making it almost linear in complexity), but it could easily grow and become
+-- too slow.
+--
+module Physics.TwoDimensions.GameCollisions where
+
+import Data.List
+import Data.Maybe
+import Data.IdentityList
+import Physics.TwoDimensions.Collisions
+import qualified Physics.TwoDimensions.Collisions as C
+import Physics.TwoDimensions.PhysicalObjects
+import Physics.TwoDimensions.Shapes
+
+-- | Given a list of objects, it detects all the collisions between them.
+--
+-- Note: this is a simple n*m-complex algorithm, with n the
+-- number of objects and m the number of moving objects (right now,
+-- only 2).
+--
+detectCollisions :: (Eq n , PhysicalObject o n Shape) => IL o -> Collisions n
+detectCollisions = detectCollisionsH
+ where detectCollisionsH objsT = flattened
+ where -- Eliminate empty collision sets
+ -- TODO: why is this really necessary?
+ flattened = filter (\(C.Collision n) -> not (null n)) collisions
+
+ -- Detect collisions between moving objects and any other objects
+ collisions = detectCollisions' objsT moving
+
+ -- Partition the object space between moving and static objects
+ (moving, _static) = partition (physObjectCollides.snd) $ assocsIL objsT
+
+-- | Detect collisions between each moving object and
+-- every other object.
+detectCollisions' :: (Eq n, PhysicalObject o n Shape) => IL o -> [(ILKey, o)] -> [Collision n]
+detectCollisions' objsT ms = concatMap (detectCollisions'' objsT) ms
+
+-- | Detect collisions between one specific moving object and every existing
+-- object. Each collision is idependent of the rest (which is not necessarily
+-- what should happen, but since the transformed velocities are eventually
+-- added, there isn't much difference in the end).
+detectCollisions'' :: (Eq n, PhysicalObject o n Shape) => IL o -> (ILKey, o ) -> [Collision n]
+detectCollisions'' objsT m = concatMap (detectCollisions''' m) (assocsIL objsT)
+
+-- | Detect a possible collision between two objects. Uses the object's keys to
+-- distinguish them. Uses the basic 'Object'-based 'detectCollision' to
+-- determine whether the two objects do collide.
+detectCollisions''' :: (Eq n, PhysicalObject o n Shape) => (ILKey, o) -> (ILKey, o) -> [Collision n]
+detectCollisions''' m o
+ | fst m == fst o = [] -- Same object -> no collision
+ | otherwise = maybeToList (detectCollision (snd m) (snd o))
diff --git a/Experiments/collisions/Physics/TwoDimensions/PhysicalObjects.hs b/Experiments/collisions/Physics/TwoDimensions/PhysicalObjects.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/collisions/Physics/TwoDimensions/PhysicalObjects.hs
@@ -0,0 +1,16 @@
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE FunctionalDependencies #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+module Physics.TwoDimensions.PhysicalObjects where
+
+import Physics.TwoDimensions.Dimensions
+
+class Eq b => PhysicalObject a b c | a -> b, a -> c where
+ physObjectPos :: a -> Pos2D
+ physObjectVel :: a -> Vel2D
+ physObjectElas :: a -> Double
+ physObjectShape :: a -> c
+ physObjectCollides :: a -> Bool
+ physObjectId :: a -> b
+ physObjectUpdatePos :: a -> Pos2D -> a
+ physObjectUpdateVel :: a -> Vel2D -> a
diff --git a/Experiments/collisions/Physics/TwoDimensions/Shapes.hs b/Experiments/collisions/Physics/TwoDimensions/Shapes.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/collisions/Physics/TwoDimensions/Shapes.hs
@@ -0,0 +1,45 @@
+-- | A very simple physics subsytem. It currently detects shape
+-- overlaps only, the actual physics movement is carried out
+-- in Yampa itself, as it is very simple using integrals and
+-- derivatives.
+module Physics.TwoDimensions.Shapes where
+
+import FRP.Yampa.VectorSpace
+import Physics.TwoDimensions.Dimensions
+
+-- | Side of a rectangle
+data Side = TopSide | BottomSide | LeftSide | RightSide
+ deriving (Eq,Show)
+
+-- | Opposite side
+--
+-- If A collides with B, the collision sides on
+-- A and B are always opposite.
+oppositeSide :: Side -> Side
+oppositeSide TopSide = BottomSide
+oppositeSide BottomSide = TopSide
+oppositeSide LeftSide = RightSide
+oppositeSide RightSide = LeftSide
+
+data Shape = -- Rectangle Pos2D Size2D -- A corner and the whole size
+ Circle Pos2D Double -- Position and radius
+ | SemiPlane Pos2D Side --
+
+-- | Detects if two shapes overlap.
+--
+-- Rectangles: overlap if projections on both axis overlap,
+-- which happens if x distance between centers is less than the sum
+-- of half the widths, and the analogous for y and the heights.
+
+overlapShape :: Shape -> Shape -> Bool
+overlapShape (Circle p1 s1) (Circle p2 s2) = (dist - (s1 + s2)) < sigma
+ where (dx, dy) = p2 ^-^ p1
+ dist = sqrt (dx**2 + dy**2)
+ sigma = 1
+overlapShape (Circle (p1x,p1y) s1) (SemiPlane (px,py) side) = case side of
+ LeftSide -> p1x - s1 <= px
+ RightSide -> p1x + s1 >= px
+ TopSide -> p1y - s1 <= py
+ BottomSide -> p1y + s1 >= py
+overlapShape s@(SemiPlane _ _) c@(Circle _ _) = overlapShape c s
+overlapShape _ _ = False -- Not really, it's just that we don't care
diff --git a/Experiments/collisions/Resources.hs b/Experiments/collisions/Resources.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/collisions/Resources.hs
@@ -0,0 +1,10 @@
+module Resources where
+
+import qualified Graphics.UI.SDL.TTF as TTF
+
+-- import Game.Audio
+
+data Resources = Resources
+ { resFont :: TTF.Font
+ , miniFont :: TTF.Font
+ }
diff --git a/Experiments/dumbplayer/Main.hs b/Experiments/dumbplayer/Main.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/dumbplayer/Main.hs
@@ -0,0 +1,170 @@
+{-# LANGUAGE Arrows #-}
+import Graphics.UI.SDL as SDL
+import FRP.Yampa as Yampa
+import Data.IORef
+import Debug.Trace
+
+width = 640
+height = 480
+
+main = do
+ timeRef <- newIORef (0 :: Int)
+ controllerRef <- newIORef $ Controller False False False False -- (Controller Nothing)
+ reactimate (initGraphs >> readIORef controllerRef)
+ (\_ -> do
+ dtSecs <- yampaSDLTimeSense timeRef
+ mInput <- sdlGetController controllerRef
+ -- print (mInput)
+ return (dtSecs, Just mInput)
+ )
+ (\_ e -> display ((0,0),e) >> return False)
+ (player initialPos)
+
+-- | Updates the time in an IO Ref and returns the time difference
+updateTime :: IORef Int -> Int -> IO Int
+updateTime timeRef newTime = do
+ previousTime <- readIORef timeRef
+ writeIORef timeRef newTime
+ return (newTime - previousTime)
+
+yampaSDLTimeSense :: IORef Int -> IO Yampa.DTime
+yampaSDLTimeSense timeRef = do
+ -- Get time passed since SDL init
+ newTime <- fmap fromIntegral SDL.getTicks
+
+ -- Obtain time difference
+ dt <- updateTime timeRef newTime
+ let dtSecs = fromIntegral dt / 100
+ return dtSecs
+
+-- We need a non-blocking controller-polling function.
+sdlGetController :: IORef Controller -> IO Controller
+sdlGetController controllerState = do
+ state <- readIORef controllerState
+ e <- pollEvent
+ case e of
+ KeyDown v | keyDirection v -> updateControllerState controllerState v True >> sdlGetController controllerState
+ KeyUp v | keyDirection v -> updateControllerState controllerState v False >> sdlGetController controllerState
+ _ -> return state
+
+keyDirection :: Keysym -> Bool
+keyDirection (Keysym SDLK_w _ _) = True
+keyDirection (Keysym SDLK_s _ _) = True
+keyDirection (Keysym SDLK_a _ _) = True
+keyDirection (Keysym SDLK_d _ _) = True
+keyDirection _ = False
+
+updateControllerState :: IORef Controller -> Keysym -> Bool -> IO ()
+updateControllerState stateRef input state = modifyIORef stateRef (applyInput input state)
+
+applyInput :: Keysym -> Bool -> Controller -> Controller
+applyInput input apply c = keyF input apply
+ where keyF (Keysym SDLK_w _ _) s = c { controllerUp = s }
+ keyF (Keysym SDLK_a _ _) s = c { controllerLeft = s }
+ keyF (Keysym SDLK_s _ _) s = c { controllerDown = s }
+ keyF (Keysym SDLK_d _ _) s = c { controllerRight = s }
+
+
+data Controller = Controller
+ { controllerUp :: Bool
+ , controllerDown :: Bool
+ , controllerLeft :: Bool
+ , controllerRight :: Bool
+ }
+
+getVelocity :: Controller -> (Double, Double)
+getVelocity rc = (rx, ry)
+ where ry = rup + rdown
+ rx = rleft + rright
+ rup = if controllerUp rc then -1 else 0
+ rdown = if controllerDown rc then 1 else 0
+ rleft = if controllerLeft rc then -1 else 0
+ rright = if controllerRight rc then 1 else 0
+
+initGraphs :: IO ()
+initGraphs = do
+ -- Initialise SDL
+ SDL.init [InitVideo]
+
+ -- Create window
+ screen <- SDL.setVideoMode width height 16 [SWSurface]
+ SDL.setCaption "Test" ""
+
+ -- Important if we want the keyboard to work right (I don't know
+ -- how to make it work otherwise)
+ SDL.enableUnicode True
+
+display :: ((Double, Double),(Double, Double)) -> IO()
+display ((boxY,_), (playerX, playerY)) = do
+ -- Obtain surface
+ screen <- getVideoSurface
+
+ -- Paint screen green
+ let format = surfaceGetPixelFormat screen
+ green <- mapRGB format 0 0xFF 0
+ fillRect screen Nothing green
+
+ -- Paint small red square, at an angle 'angle' with respect to the center
+ red <- mapRGB format 0xFF 0 0
+ let side = 10
+ x = (width - side) `div` 2
+ y = round boxY
+ fillRect screen (Just (Rect x y side side)) red
+
+ drawPlayer screen (round playerX, round playerY)
+
+ -- Double buffering
+ SDL.flip screen
+
+drawPlayer surface (playerX, playerY) = do
+ let format = surfaceGetPixelFormat surface
+ red <- mapRGB format 0xFF 0 0
+ let side = 10
+ x = playerX
+ y = playerY
+ fillRect surface (Just (Rect x y side side)) red
+
+-- | Moves by default using playerProgress, unless the player is
+-- slowing down and barely moving, in which case we discard any
+-- remanent velocity and reinitiate the player from the new position.
+player :: (Double, Double) -> SF Controller (Double, Double)
+player p0 = switch (playerProgress p0 >>> (arr fst &&& isTooSmall)) player
+ where isTooSmall :: SF ((Double, Double), (Double, Double)) (Yampa.Event (Double, Double))
+ isTooSmall = proc (pos,diffV) -> do
+ derivV <- derivative -< diffV
+ returnA -< if shouldStop diffV derivV
+ then Yampa.Event pos
+ else Yampa.NoEvent
+
+shouldStop :: (Double, Double) -> (Double, Double) -> Bool
+shouldStop (dx, dy) (diffVX, diffVY) =
+ abs dx < margin && abs dy < margin -- Small movement
+ && sign dx * diffVX <= 0 && diffVY * sign dy <= 0 -- Slowing down
+ && (abs dy > 0 || abs dx > 0) -- But moving (break in switch loop)
+ where margin = 0.1
+
+playerProgress :: (Double, Double) -> SF Controller ((Double, Double), (Double, Double))
+playerProgress p0 = proc (c) -> do
+ rec let acc = getVelocity c -- Acceleration (depends on user input)
+ v <- integral -< acc -- Velocity according to user input
+ vdiff <- integral -< 0.1 *^ vtotal -- "Air" resistance (note: I get strange flickers with exponentiation)
+ let vtotal = v ^-^ vdiff -- Subtract resistance from velocity (FIXME: make sure we don't move back")
+ p <- (p0 ^+^) ^<< integral -< vtotal -- Add to initial position
+ returnA -< (p, vtotal)
+
+-- | FIXME: the old code (commented out) contains a "bug" that makes
+-- it misbehave when you change direction twice without stopping.
+-- But this code does not guarantee that resistance is not greater than
+-- current velocity, which means that (theoretically) it could drag the
+-- player back even if it's stopped. I don't know if that can happen
+-- because I don't understand how rec works above (but I wrote the thing ;)
+-- applyResistance :: (Double, Double) -> (Double, Double) -> (Double, Double)
+-- applyResistance (vx, vy) (vdx, vdy) = (vx', vy')
+-- where vx' = if abs vdx > abs vx then 0 else (vx - vdx)
+-- vy' = if abs vdy > abs vy then 0 else (vy - vdy)
+
+sign :: Double -> Double
+sign d | d < 0 = -1
+ | otherwise = 1
+
+initialPos = (fromIntegral width/2, fromIntegral height/2)
diff --git a/Experiments/player/Main.hs b/Experiments/player/Main.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/player/Main.hs
@@ -0,0 +1,209 @@
+{-# LANGUAGE Arrows #-}
+import Control.Monad
+import Data.IORef
+import Data.Maybe
+import Debug.Trace
+import FRP.Yampa as Yampa
+import FRP.Yampa.Switches as Yampa
+import Graphics.UI.SDL as SDL
+import Graphics.UI.SDL.Primitives as SDL
+
+width = 640
+height = 480
+
+main = do
+ timeRef <- newIORef (0 :: Int)
+ controllerRef <- newIORef defaultController
+ reactimate (initGraphs >> readIORef controllerRef)
+ (\_ -> do
+ dtSecs <- yampaSDLTimeSense timeRef
+ mInput <- sdlGetController controllerRef
+ -- print (mInput)
+ return (dtSecs, Just mInput)
+ )
+ (\_ e -> display e >> return False)
+ (dlSwitch [player] >>> arr composeWorld)
+
+-- | Updates the time in an IO Ref and returns the time difference
+updateTime :: IORef Int -> Int -> IO Int
+updateTime timeRef newTime = do
+ previousTime <- readIORef timeRef
+ writeIORef timeRef newTime
+ return (newTime - previousTime)
+
+yampaSDLTimeSense :: IORef Int -> IO Yampa.DTime
+yampaSDLTimeSense timeRef = do
+ -- Get time passed since SDL init
+ newTime <- fmap fromIntegral SDL.getTicks
+
+ -- Obtain time difference
+ dt <- updateTime timeRef newTime
+ let dtSecs = fromIntegral dt / 100
+ return dtSecs
+
+-- We need a non-blocking controller-polling function.
+sdlGetController :: IORef Controller -> IO Controller
+sdlGetController controllerState = do
+ state <- readIORef controllerState
+ e <- pollEvent
+ case e of
+
+ -- Update position
+ MouseMotion x y _ _ -> do
+ writeIORef controllerState (state { controllerPos = (fromIntegral x, fromIntegral y)})
+ sdlGetController controllerState
+
+ -- Fire 1
+ MouseButtonDown x y ButtonLeft -> do
+ writeIORef controllerState (state { controllerFire1 = True })
+ sdlGetController controllerState
+
+ MouseButtonUp x y ButtonLeft -> do
+ writeIORef controllerState (state { controllerFire1 = False })
+ sdlGetController controllerState
+
+ MouseButtonDown x y ButtonRight -> do
+ writeIORef controllerState (state { controllerFire2 = True })
+ sdlGetController controllerState
+
+ MouseButtonUp x y ButtonRight -> do
+ writeIORef controllerState (state { controllerFire2 = False })
+ sdlGetController controllerState
+
+ _ -> return state
+
+data Controller = Controller
+ { controllerPos :: (Double, Double)
+ , controllerFire1 :: Bool
+ , controllerFire2 :: Bool
+ }
+
+defaultController :: Controller
+defaultController = Controller (0, 0) False False
+
+initGraphs :: IO ()
+initGraphs = do
+ -- Initialise SDL
+ SDL.init [InitVideo]
+
+ -- Create window
+ screen <- SDL.setVideoMode width height 16 [SWSurface]
+ SDL.setCaption "Test" ""
+
+ -- Important if we want the keyboard to work right (I don't know
+ -- how to make it work otherwise)
+ SDL.enableUnicode True
+
+display :: World -> IO()
+display world = do
+ -- Obtain surface
+ screen <- getVideoSurface
+
+ -- Necessary colors
+ let format = surfaceGetPixelFormat screen
+ red <- mapRGB format 0xFF 0 0
+ green <- mapRGB format 0x87 0xFF 0x87
+ blue <- mapRGB format 0 0 0xFF
+ otherRed <- mapRGBA format 0xFF 0xFF 0x00 0xFF
+
+ -- Paint screen green
+ fillRect screen Nothing green
+
+ -- Paint small red square
+ case worldPlayer world of
+ Just (Player (playerX, playerY)) -> void $ do
+ let side = 10
+ x = round playerX
+ y = round playerY
+ fillRect screen (Just (Rect x y side side)) red
+ _ -> return ()
+
+ -- Paint vertical lines for all fire arrows
+ let paintFire f = do
+ let fireColor = if fireSticky f then blue else otherRed
+ (x0,y0) = fireOrigin f
+ (x1,y1) = fireTip f
+ (dx, dy) = (3, y0-y1)
+ (x1', y1') = (round x1, round y1)
+ (x0', y0', dx', dy') = (round x0 - 1, round y0, round dx, round dy)
+ fillRect screen (Just (Rect x1' y1' dx' dy')) fireColor
+ print f
+ -- vLine screen x0' y0' y1' fireColor
+ -- vLine screen (x0'+1) y0' y1' fireColor
+ -- vLine screen (x0'+2) y0' y1' fireColor
+
+ mapM_ paintFire (worldFires world)
+
+ -- Double buffering
+ SDL.flip screen
+
+data World = World
+ { worldPlayer :: Maybe Player
+ , worldFires :: [Fire]
+ }
+
+composeWorld :: [Object] -> World
+composeWorld objs = World pl fs
+ where pl = listToMaybe $ mapMaybe objectPlayer objs
+ fs = mapMaybe objectFire objs
+
+objectPlayer :: Object -> Maybe Player
+objectPlayer (ObjectPlayer pl) = Just pl
+objectPlayer _ = Nothing
+
+objectFire :: Object -> Maybe Fire
+objectFire (ObjectFire pl) = Just pl
+objectFire _ = Nothing
+
+data Object = ObjectPlayer Player
+ | ObjectFire Fire
+ deriving Show
+
+data Player = Player { playerPos :: (Double, Double) }
+ deriving Show
+
+data Fire = Fire { fireOrigin :: (Double, Double)
+ , fireTip :: (Double, Double)
+ , fireSticky :: Bool
+ }
+ deriving Show
+
+-- | A player that may die or spawn new objects.
+player :: ListSF Controller Object
+player = ListSF $ proc (Controller p f1 f2) -> do
+
+ let this = ObjectPlayer $ Player p
+ newF1 <- isEvent ^<< edge -< f1
+ newF2 <- isEvent ^<< edge -< f2
+
+ let newF1Arrows = [ fire p False | newF1 ]
+ newF2Arrows = [ fire p True | newF2 ]
+ allArrows = newF1Arrows ++ newF2Arrows
+
+ returnA -< (this, False, allArrows)
+
+ where initialPos = (fromIntegral width / 2, fromIntegral height / 2)
+
+-- | This produces bullets that die when they hit the top of the screen.
+-- There's sticky bullets and normal bullets. Sticky bullets get stuck for a
+-- while before they die.
+fire :: (Double, Double) -> Bool -> ListSF Controller Object
+fire (x0, y0) sticky = ListSF $ proc _ -> do
+ let v0 = -10
+
+ -- Calculate tip of arrow
+ yT <- (y0+) ^<< integral -< v0
+ let y = max 0 yT
+
+ -- Delay death if the fire is "sticky"
+ hit <- switch (constant noEvent &&& (arr (<= 0) >>> edge))
+ (\_ -> stickyDeath sticky)
+ -< y
+ let dead = isEvent hit
+
+ let object = ObjectFire $ Fire (x0, y0) (x0, y) sticky
+
+ returnA -< (object, dead, [])
+
+stickyDeath True = after 30 ()
+stickyDeath False = constant (Event ())
diff --git a/Experiments/split/Main.hs b/Experiments/split/Main.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/split/Main.hs
@@ -0,0 +1,207 @@
+{-# LANGUAGE Arrows #-}
+import Graphics.UI.SDL as SDL
+import FRP.Yampa as Yampa
+import Data.IORef
+import Debug.Trace
+
+width = 640
+height = 480
+
+main = do
+ timeRef <- newIORef (0 :: Int)
+ controllerRef <- newIORef $ Controller False False False False False
+ reactimate (initGraphs >> readIORef controllerRef)
+ (\_ -> do
+ dtSecs <- yampaSDLTimeSense timeRef
+ mInput <- sdlGetController controllerRef
+ -- print (mInput)
+ return (dtSecs, Just mInput)
+ )
+ (\_ e -> display ((0,0), fst e) >> return False)
+ (bounce initialPos)
+
+-- | Updates the time in an IO Ref and returns the time difference
+updateTime :: IORef Int -> Int -> IO Int
+updateTime timeRef newTime = do
+ previousTime <- readIORef timeRef
+ writeIORef timeRef newTime
+ return (newTime - previousTime)
+
+yampaSDLTimeSense :: IORef Int -> IO Yampa.DTime
+yampaSDLTimeSense timeRef = do
+ -- Get time passed since SDL init
+ newTime <- fmap fromIntegral SDL.getTicks
+
+ -- Obtain time difference
+ dt <- updateTime timeRef newTime
+ let dtSecs = fromIntegral dt / 100
+ return dtSecs
+
+-- We need a non-blocking controller-polling function.
+sdlGetController :: IORef Controller -> IO Controller
+sdlGetController controllerState = do
+ state <- readIORef controllerState
+ e <- pollEvent
+ case e of
+ KeyDown v | keyDirection v -> updateControllerState controllerState v True >> sdlGetController controllerState
+ KeyUp v | keyDirection v -> updateControllerState controllerState v False >> sdlGetController controllerState
+ _ -> return state
+
+keyDirection :: Keysym -> Bool
+keyDirection (Keysym SDLK_w _ _) = True
+keyDirection (Keysym SDLK_s _ _) = True
+keyDirection (Keysym SDLK_a _ _) = True
+keyDirection (Keysym SDLK_d _ _) = True
+keyDirection _ = False
+
+updateControllerState :: IORef Controller -> Keysym -> Bool -> IO ()
+updateControllerState stateRef input state = modifyIORef stateRef (applyInput input state)
+
+applyInput :: Keysym -> Bool -> Controller -> Controller
+applyInput input apply c = keyF input apply
+ where keyF (Keysym SDLK_w _ _) s = c { controllerUp = s }
+ keyF (Keysym SDLK_a _ _) s = c { controllerLeft = s }
+ keyF (Keysym SDLK_s _ _) s = c { controllerDown = s }
+ keyF (Keysym SDLK_d _ _) s = c { controllerRight = s }
+ keyF (Keysym SDLK_SPACE _ _) s = c { controllerRight = s }
+
+
+data Controller = Controller
+ { controllerUp :: Bool
+ , controllerDown :: Bool
+ , controllerLeft :: Bool
+ , controllerRight :: Bool
+ , controllerFire :: Bool
+ }
+
+getVelocity :: Controller -> (Double, Double)
+getVelocity rc = (rx, ry)
+ where ry = rup + rdown
+ rx = rleft + rright
+ rup = if controllerUp rc then -1 else 0
+ rdown = if controllerDown rc then 1 else 0
+ rleft = if controllerLeft rc then -1 else 0
+ rright = if controllerRight rc then 1 else 0
+
+initGraphs :: IO ()
+initGraphs = do
+ -- Initialise SDL
+ SDL.init [InitVideo]
+
+ -- Create window
+ screen <- SDL.setVideoMode width height 16 [SWSurface]
+ SDL.setCaption "Test" ""
+
+ -- Important if we want the keyboard to work right (I don't know
+ -- how to make it work otherwise)
+ SDL.enableUnicode True
+
+display :: ((Double, Double),(Double, Double)) -> IO()
+display ((boxY,_), (playerX, playerY)) = do
+ -- Obtain surface
+ screen <- getVideoSurface
+
+ -- Paint screen green
+ let format = surfaceGetPixelFormat screen
+ green <- mapRGB format 0 0xFF 0
+ fillRect screen Nothing green
+
+ -- Paint small red square, at an angle 'angle' with respect to the center
+ red <- mapRGB format 0xFF 0 0
+ let side = 10
+ x = (width - side) `div` 2
+ y = round boxY
+ fillRect screen (Just (Rect x y side side)) red
+
+ drawPlayer screen (round playerX, round playerY)
+
+ -- Double buffering
+ SDL.flip screen
+
+drawPlayer surface (playerX, playerY) = do
+ let format = surfaceGetPixelFormat surface
+ red <- mapRGB format 0xFF 0 0
+ let side = 10
+ x = playerX
+ y = playerY
+ fillRect surface (Just (Rect x y side side)) red
+
+-- | Moves by default using playerProgress, unless the player is
+-- slowing down and barely moving, in which case we discard any
+-- remanent velocity and reinitiate the player from the new position.
+player :: (Pos2, (Double, Double)) -> SF Controller (Pos2, (Double, Double))
+player (p0, v0) = switch (playerProgress (p0, v0) >>> (arr id &&& isTooSmall)) player
+ where isTooSmall :: SF ((Double, Double), (Double, Double)) (Yampa.Event ((Double, Double), Pos2))
+ isTooSmall = proc (pos,diffV) -> do
+ derivV <- derivative -< diffV
+ returnA -< if shouldStop diffV derivV
+ then Yampa.Event (pos, derivV)
+ else Yampa.NoEvent
+
+shouldStop :: (Double, Double) -> (Double, Double) -> Bool
+shouldStop (dx, dy) (diffVX, diffVY) =
+ abs dx < margin && abs dy < margin -- Small movement
+ && sign dx * diffVX <= 0 && diffVY * sign dy <= 0 -- Slowing down
+ && (abs dy > 0 || abs dx > 0) -- But moving (break in switch loop)
+ where margin = 0.1
+
+playerProgress :: (Pos2, Pos2) -> SF Controller ((Double, Double), (Double, Double))
+playerProgress (p0, v0) = proc (c) -> do
+ rec let acc = getVelocity c -- Acceleration (depends on user input)
+ v <- integral -< acc -- Velocity according to user input
+ vdiff <- integral -< 0.1 *^ vtotal -- "Air" resistance (note: I get strange flickers with exponentiation)
+ let vtotal = v0 ^+^ v ^-^ vdiff -- Subtract resistance from velocity (FIXME: make sure we don't move back")
+ p <- (p0 ^+^) ^<< integral -< vtotal -- Add to initial position
+ returnA -< (p, vtotal)
+
+-- | FIXME: the old code (commented out) contains a "bug" that makes
+-- it misbehave when you change direction twice without stopping.
+-- But this code does not guarantee that resistance is not greater than
+-- current velocity, which means that (theoretically) it could drag the
+-- player back even if it's stopped. I don't know if that can happen
+-- because I don't understand how rec works above (but I wrote the thing ;)
+-- applyResistance :: (Double, Double) -> (Double, Double) -> (Double, Double)
+-- applyResistance (vx, vy) (vdx, vdy) = (vx', vy')
+-- where vx' = if abs vdx > abs vx then 0 else (vx - vdx)
+-- vy' = if abs vdy > abs vy then 0 else (vy - vdy)
+
+sign :: Double -> Double
+sign d | d < 0 = -1
+ | otherwise = 1
+
+initialPos = (fromIntegral width/2, fromIntegral height/2)
+
+bounce :: Pos2 -> SF Controller (Pos2, Vel2)
+bounce y0 = bounce' y0 (0, 0) -- (-20)
+ where bounce' y vy = -- trace (show (y, vy)) $
+ switch (player (y,vy) >>> (Yampa.identity &&& hitFrame))
+ (\(y, vy) -> trace (show vy) $ bounce' y vy)
+ side = 10
+
+-- | Detects whether the ball hits the surrounding frame. This is an adhoc
+-- function with knowledge of:
+-- * Ball shape
+-- * Frame shape
+-- * Ball size
+-- * Rectangular hits, side to side only
+-- For these reasons, it is a subideal solution, very unlikely also subobtimal
+-- also in terms of speed. So, it would be best to switch to real collision
+-- detections with a surrounding frame.
+hitFrame :: SF (Pos2,Vel2) (Yampa.Event (Pos2, Vel2))
+hitFrame = arr hitFrame'
+ where hitFrame' (pos,vel)
+ | hits == (1.0,1.0) = Yampa.NoEvent
+ | otherwise = Yampa.Event (pos, vel')
+ where hits = foldr mergeHit (1,1) [hitB, hitT, hitL, hitR]
+ hitB = if (y + side) > fromIntegral height && vy > 0.0 then (1, -1) else (1,1)
+ hitT = if y < 0.0 && vy < 0.0 then (1, -1) else (1,1)
+ hitL = if x < 0.0 && vx < 0.0 then (-1, 1) else (1,1)
+ hitR = if (x + side) > fromIntegral width && vx > 0.0 then (-1, 1) else (1,1)
+ (x, y) = pos
+ (vx, vy) = vel
+ mergeHit (p1, p2) (q1, q2) = (p1 * q1, p2 * q2)
+ vel' = (vx * fst hits, vy * snd hits)
+ side = 10
+
+type Pos2 = (Double, Double)
+type Vel2 = (Double, Double)
diff --git a/Experiments/splitballs/Constants.hs b/Experiments/splitballs/Constants.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/splitballs/Constants.hs
@@ -0,0 +1,44 @@
+module Constants where
+
+import Data.Int
+import Data.Word
+import Graphics.UI.SDL as SDL
+
+width :: Double
+width = 1024
+height :: Double
+height = 600
+
+gameWidth :: Double
+gameWidth = width
+
+gameHeight :: Double
+gameHeight = height
+
+-- Energy transmission between objects in collisions
+velTrans :: Double
+velTrans = 1.00
+
+-- Max speed
+maxVNorm :: Double
+maxVNorm = 500
+
+ballWidth, ballHeight :: Double
+ballWidth = 25
+ballHeight = 25
+
+ballMargin :: Double
+ballMargin = 3
+
+ballSize :: Int16
+ballSize = 25
+
+-- Colors
+fontColor :: SDL.Color
+fontColor = SDL.Color 228 228 228
+
+ballColor :: Word32
+ballColor = 0xCC0011FF
+
+velColor :: Word32
+velColor = 0xCCBBFFFF
diff --git a/Experiments/splitballs/Control/Extra/Monad.hs b/Experiments/splitballs/Control/Extra/Monad.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/splitballs/Control/Extra/Monad.hs
@@ -0,0 +1,19 @@
+module Control.Extra.Monad where
+
+import Control.Monad
+
+whileLoopM :: Monad m => m a -> (a -> Bool) -> (a -> m ()) -> m ()
+whileLoopM val cond act = r'
+ where r' = do v <- val
+ when (cond v) $ do
+ act v
+ whileLoopM val cond act
+
+foldLoopM :: Monad m => a -> m b -> (b -> Bool) -> (a -> b -> m a) -> m a
+foldLoopM val sense cond act = r'
+ where r' = do s <- sense
+ if cond s
+ then do
+ val' <- act val s
+ foldLoopM val' sense cond act
+ else return val
diff --git a/Experiments/splitballs/Data/Extra/Num.hs b/Experiments/splitballs/Data/Extra/Num.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/splitballs/Data/Extra/Num.hs
@@ -0,0 +1,20 @@
+module Data.Extra.Num where
+
+ensurePos :: (Eq a, Num a) => a -> a
+ensurePos e = if signum e == (-1) then negate e else e
+
+ensureNeg :: (Eq a, Num a) => a -> a
+ensureNeg e = if signum e == 1 then negate e else e
+
+class Similar a where
+ sigma :: a -- margin of error
+
+instance Similar Float where
+ sigma = 0.01
+
+instance Similar Double where
+ sigma = 0.01
+
+(=~) :: (Num a, Ord a, Similar a) => a -> a -> Bool
+x =~ y = abs (x - y) < sigma
+
diff --git a/Experiments/splitballs/Data/Extra/VectorSpace.hs b/Experiments/splitballs/Data/Extra/VectorSpace.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/splitballs/Data/Extra/VectorSpace.hs
@@ -0,0 +1,6 @@
+module Data.Extra.VectorSpace where
+
+import FRP.Yampa.VectorSpace
+
+limitNorm :: (Ord s, VectorSpace v s) => v -> s -> v
+limitNorm v mn = if norm v > mn then mn *^ normalize v else v
diff --git a/Experiments/splitballs/Debug.hs b/Experiments/splitballs/Debug.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/splitballs/Debug.hs
@@ -0,0 +1,8 @@
+module Debug where
+
+import Control.Monad (when, void)
+
+import Constants
+
+debug :: Bool -> String -> IO ()
+debug b msg = when b $ putStrLn msg
diff --git a/Experiments/splitballs/Display.hs b/Experiments/splitballs/Display.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/splitballs/Display.hs
@@ -0,0 +1,117 @@
+module Display where
+
+import Control.Arrow ((***))
+import Control.Monad
+import FRP.Yampa.VectorSpace
+import Graphics.UI.SDL as SDL
+import qualified Graphics.UI.SDL.Primitives as SDLP
+import qualified Graphics.UI.SDL.TTF as TTF
+import Text.Printf
+
+import Constants
+import GameState
+import Objects
+import Resources
+
+-- | Ad-hoc resource loading
+-- This function is ad-hoc in two senses: first, because it
+-- has the paths to the files hard-coded inside. And second,
+-- because it loads the specific resources that are needed,
+-- so it's not a general, parameterised, scalable solution.
+--
+loadResources :: IO Resources
+loadResources = do
+ -- Font initialization
+ _ <- TTF.init
+
+ -- Load the fonts we need
+ let gameFont = "data/lacuna.ttf"
+ font <- TTF.openFont gameFont 32 -- 32: fixed size?
+ let myFont = font
+
+ -- Load the fonts we need
+ let gameFont = "data/lacuna.ttf"
+ font2 <- TTF.openFont gameFont 8 -- 32: fixed size?
+ let myFont2 = font2
+
+ -- Return all resources (just the font)
+ return $ Resources myFont myFont2
+
+initializeDisplay :: IO ()
+initializeDisplay =
+ -- Initialise SDL
+ SDL.init [InitEverything]
+
+initGraphs :: Resources -> IO ()
+initGraphs _res = do
+ screen <- SDL.setVideoMode (round width) (round height) 32 [SWSurface]
+ SDL.setCaption "Voldemort" ""
+
+ -- Important if we want the keyboard to work right (I don't know
+ -- how to make it work otherwise)
+ SDL.enableUnicode True
+
+ -- Hide mouse
+ SDL.showCursor True
+
+ return ()
+
+render :: Resources -> GameState -> IO()
+render resources shownState = do
+ -- Obtain surface
+ screen <- getVideoSurface
+
+ let format = surfaceGetPixelFormat screen
+ bgColor <- mapRGB format 0x37 0x16 0xB4
+ fillRect screen Nothing bgColor
+
+ mapM_ (paintObject screen resources ) $ gameObjects shownState
+
+ displayInfo screen resources (gameInfo shownState)
+
+ -- Double buffering
+ SDL.flip screen
+
+-- * Painting functions
+displayInfo :: Surface -> Resources -> GameInfo -> IO()
+displayInfo screen resources over =
+ printAlignRight screen resources
+ ("Time: " ++ printf "%.3f" (gameTime over)) (10,50)
+
+paintObject :: Surface -> Resources -> Object -> IO ()
+paintObject screen resources object =
+ case objectKind object of
+ (Side {}) -> return ()
+ (Ball ballSize) -> do
+ let (px,py) = (\(u,v) -> (u, gameHeight - v)) (objectPos object)
+ let (x,y) = (round *** round) (px,py)
+ (vx,vy) = objectVel object
+ (x',y') = (round *** round) ((px,py) ^+^ (0.1 *^ (vx, -vy)))
+ _ <- SDLP.filledCircle screen x y (round ballSize) (SDL.Pixel ballColor)
+ _ <- SDLP.line screen x y x' y' (SDL.Pixel velColor)
+
+ -- Print position
+ let font = miniFont resources
+ message <- TTF.renderTextSolid font (show $ (round *** round) (objectPos object)) fontColor
+ let w = SDL.surfaceGetWidth message
+ h = SDL.surfaceGetHeight message
+ (x'',y'') = (round *** round) (px,py)
+ rect = SDL.Rect (x''+30) (y''-30) w h
+ SDL.blitSurface message Nothing screen (Just rect)
+ return ()
+
+-- * Render text with alignment
+printAlignRight :: Surface -> Resources -> String -> (Int, Int) -> IO ()
+printAlignRight screen resources msg (x,y) = void $ do
+ let font = resFont resources
+ message <- TTF.renderTextSolid font msg fontColor
+ renderAlignRight screen message (x,y)
+
+-- * SDL Extensions
+renderAlignRight :: Surface -> Surface -> (Int, Int) -> IO ()
+renderAlignRight screen surface (x,y) = void $ do
+ let rightMargin = SDL.surfaceGetWidth screen
+ w = SDL.surfaceGetWidth surface
+ h = SDL.surfaceGetHeight surface
+ rect = SDL.Rect (rightMargin - x - w) y w h
+ SDL.blitSurface surface Nothing screen (Just rect)
diff --git a/Experiments/splitballs/Game.hs b/Experiments/splitballs/Game.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/splitballs/Game.hs
@@ -0,0 +1,301 @@
+{-# LANGUAGE Arrows #-}
+-- | This module defines the game as a big Signal Function that transforms a
+-- Signal carrying a Input 'Controller' information into a Signal carrying
+-- 'GameState'.
+--
+-- There is no randomness in the game, the only input is the user's.
+-- 'Controller' is an abstract representation of a basic input device with
+-- position information and a /fire/ button.
+--
+-- The output is defined in 'GameState', and consists of basic information
+-- (points, current level, etc.) and a universe of objects.
+--
+-- Objects are represented as Signal Functions as well ('ObjectSF'). This
+-- allows them to react to user input and change with time. Each object is
+-- responsible for itself, but it cannot affect others: objects can watch
+-- others, depend on others and react to them, but they cannot /send a
+-- message/ or eliminate other objects. However, if you would like to
+-- dynamically introduce new elements in the game (for instance, falling
+-- powerups that the player must collect before they hit the ground) then it
+-- might be a good idea to allow objects not only to /kill themselves/ but
+-- also to spawn new object.
+--
+-- This module contains two sections:
+--
+-- - A collection of gameplay SFs, which control the core game loop, carry
+-- out collision detection, , etc.
+--
+-- - One SF per game object. These define the elements in the game universe,
+-- which can observe other elements, depend on user input, on previous
+-- collisions, etc.
+--
+-- You may want to read the basic definition of 'GameState', 'Controller' and
+-- 'ObjectSF' before you attempt to go through this module.
+--
+module Game (wholeGame) where
+
+-- External imports
+import FRP.Yampa
+import FRP.Yampa.Switches
+
+-- General-purpose internal imports
+import Data.Extra.VectorSpace
+import Physics.TwoDimensions.Collisions
+import Physics.TwoDimensions.Dimensions
+import Physics.TwoDimensions.GameCollisions
+import Physics.TwoDimensions.Shapes
+import Physics.TwoDimensions.PhysicalObjects
+
+-- Internal iports
+import Constants
+import GameState
+import Input
+import Objects
+import ObjectSF
+
+-- * General state transitions
+
+-- | Run the game that the player can lose at ('canLose'), until ('switch')
+-- there are no more levels ('outOfLevels'), in which case the player has won
+-- ('wonGame').
+wholeGame :: SF Controller GameState
+wholeGame = gamePlay initialObjects >>> composeGameState
+ where composeGameState :: SF (Objects, Time) GameState
+ composeGameState = arr (second GameInfo >>> uncurry GameState)
+
+-- ** Game with partial state information
+
+-- | Given an initial list of objects, it runs the game, presenting the output
+-- from those objects at all times, notifying any time the ball hits the floor,
+-- and and of any additional points made.
+--
+-- This works as a game loop with a post-processing step. It uses
+-- a well-defined initial accumulator and a traditional feedback
+-- loop.
+--
+-- The internal accumulator holds the last known collisions (discarded at every
+-- iteration).
+
+gamePlay :: [ListSF ObjectInput Object] -> SF Controller (Objects, Time)
+gamePlay objs = loopPre [] $
+ -- Process physical movement and detect new collisions
+ proc (i) -> do
+ -- Adapt Input
+ let oi = (uncurry ObjectInput) i
+
+ -- Step
+ -- Each obj processes its movement forward
+ ol <- dlSwitch objs -< oi
+ let cs' = detectCollisions ol
+
+ -- Output
+ tLeft <- time -< ()
+ returnA -< ((ol, tLeft), cs')
+
+-- * Game objects
+--
+-- | Objects initially present: the walls, the ball, the paddle and the blocks.
+initialObjects :: [ListSF ObjectInput Object]
+initialObjects =
+ [ inertSF objSideRight
+ , inertSF objSideTop
+ , inertSF objSideLeft
+ , inertSF objSideBottom
+ ]
+ ++ objEnemies
+
+-- *** Enemy
+objEnemies :: [ListSF ObjectInput Object]
+objEnemies =
+ [ splittingBall ballWidth "enemy1" (300, 300) (360, -350)
+ , splittingBall ballWidth "enemy2" (500, 300) (-330, -280)
+ , splittingBall ballWidth "enemy3" (200, 100) (-300, -250)
+ , splittingBall ballWidth "enemy4" (100, 200) (-200, -150)
+ ]
+
+splittingBall :: Double -> String -> Pos2D -> Vel2D -> ListSF ObjectInput Object
+splittingBall size bid p0 v0 = ListSF $ proc i -> do
+ t <- localTime -< ()
+ bo <- bouncingBall size bid p0 v0 -< i
+ click <- edge -< controllerClick (userInput i)
+ let tooSmall = size <= (ballWidth / 2)
+ shouldSplit = isEvent click
+
+ let offspringSize = (5 * size / 6) -- Or: size
+
+ let offspringID = (bid ++ show t) -- Should be unique or collisions won't work
+
+ offspring = [ splittingBall offspringSize offspringID bpos (0,0)
+ | shouldSplit && not tooSmall
+ , let bpos = physObjectPos bo
+ ]
+
+ dead = shouldSplit && tooSmall
+
+ returnA -< (bo, dead, offspring)
+
+-- *** Ball
+
+-- A bouncing ball moves freely until there is a collision, then bounces and
+-- goes on and on.
+--
+-- This SF needs an initial position and velocity. Every time
+-- there is a bounce, it takes a snapshot of the point of
+-- collision and corrected velocity, and starts again.
+--
+bouncingBall :: Double -> String -> Pos2D -> Vel2D -> ObjectSF
+bouncingBall size bid p0 v0 =
+ switch progressAndBounce
+ (uncurry (bouncingBall size bid)) -- Somehow it would be clearer like this:
+ -- \(p', v') -> bouncingBall p' v')
+ where
+
+ -- Calculate the future tentative position, and
+ -- bounce if necessary.
+ --
+ -- The ballBounce needs the ball SF' input (which has knowledge of
+ -- collisions), so we carry it parallely to the tentative new positions,
+ -- and then use it to detect when it's time to bounce
+
+ -- ========================== ============================
+ -- -==--------------------->==--->==- ------------------->==
+ -- / == == == \ / ==
+ -- -- == == == X ==
+ -- \ == == == / \ ==
+ -- -==----> freeBall' ----->==--->==--------> ballBounce -->==
+ -- ========================== ============================
+ progressAndBounce = (arr id &&& freeBall') >>> (arr snd &&& ballBounce bid)
+
+ -- Position of the ball, starting from p0 with velicity v0, since the
+ -- time of last switching (or being fired, whatever happened last)
+ -- provided that no obstacles are encountered.
+ freeBall' = freeBall size bid p0 v0
+
+-- | Detect if the ball must bounce and, if so, take a snapshot of the object's
+-- current position and velocity.
+--
+-- NOTE: To avoid infinite loops when switching, the initial input is discarded
+-- and never causes a bounce. This works in this game and in this particular
+-- case because the ball never-ever bounces immediately as fired from the
+-- paddle. This might not be true if a block is extremely close, if you add
+-- flying enemies to the game, etc.
+ballBounce :: String -> SF (ObjectInput, Object) (Event (Pos2D, Vel2D))
+ballBounce bid = noEvent --> ballBounce' bid
+
+-- | Detect if the ball must bounce and, if so, take a snapshot of the object's
+-- current position and velocity.
+--
+-- This does the core of the work, and does not ignore the initial input.
+--
+-- It proceeds by detecting whether any collision affects
+-- the ball's velocity, and outputs a snapshot of the object
+-- position and the corrected velocity if necessary.
+ballBounce' :: String -> SF (ObjectInput, Object) (Event (Pos2D, Vel2D))
+ballBounce' bid = proc (ObjectInput ci cs, o) -> do
+ -- HN 2014-09-07: With the present strategy, need to be able to
+ -- detect an event directly after
+ -- ev <- edgeJust -< changedVelocity "ball" cs
+ let ev = maybeToEvent (changedVelocity bid cs)
+ returnA -< fmap (\v -> (objectPos o, v)) ev
+
+-- | Position of the ball, starting from p0 with velicity v0, since the time of
+-- last switching (that is, collision, or the beginning of time --being fired
+-- from the paddle-- if never switched before), provided that no obstacles are
+-- encountered.
+freeBall :: Double -> String -> Pos2D -> Vel2D -> ObjectSF
+freeBall size name p0 v0 = proc (ObjectInput ci cs) -> do
+
+ -- Integrate acceleration, add initial velocity and cap speed. Resets both
+ -- the initial velocity and the current velocity to (0,0) when the user
+ -- presses the Halt key (hence the dependency on the controller input ci).
+
+ vInit <- startAs v0 -< ci
+ vel <- vdiffSF -< (vInit, (0, -100.8), ci)
+
+ -- Any free moving object behaves like this (but with
+ -- acceleration. This should be in some FRP.NewtonianPhysics
+ -- module)
+ pos <- (p0 ^+^) ^<< integral -< vel
+
+ let obj = Object { objectName = name
+ , objectKind = Ball size
+ , objectPos = pos
+ , objectVel = vel
+ , canCauseCollisions = True
+ , collisionEnergy = 1
+ }
+
+ returnA -< obj
+ where -- Spike every time the user presses the Halt key
+ restartCond = spikeOn (arr controllerStop)
+
+ -- Calculate the velocity, restarting when the user
+ -- requests it.
+ vdiffSF = proc (iv, acc, ci) -> do
+ -- Calculate velocity difference by integrating acceleration
+ -- Reset calculation when user requests to stop balls
+ vd <- restartOn (arr fst >>> integral)
+ (arr snd >>> restartCond) -< (acc, ci)
+
+ -- Add initial velocity, and cap the result
+ v <- arr (uncurry (^+^)) -< (iv, vd)
+ let vFinal = limitNorm v maxVNorm
+
+ returnA -< vFinal
+
+ -- Initial velocity, reset when the user requests it.
+ startAs v0 = switch (constant v0 &&& restartCond)
+ (\_ -> startAs (0,0))
+
+-- *** Walls
+
+-- | Walls. Each wall has a side and a position.
+--
+-- NOTE: They are considered game objects instead of having special treatment.
+-- The function that turns walls into 'Shape's for collision detection
+-- determines how big they really are. In particular, this has implications in
+-- ball-through-paper effects (ball going through objects, potentially never
+-- coming back), which can be seen if the FPS suddently drops due to CPU load
+-- (for instance, if a really major Garbage Collection kicks in. One potential
+-- optimisation is to trigger these with every SF iteration or every rendering,
+-- to decrease the workload and thus the likelyhood of BTP effects.
+objSideRight :: ObjectSF
+objSideRight = objWall "rightWall" RightSide (gameWidth, 0)
+
+-- | See 'objSideRight'.
+objSideLeft :: ObjectSF
+objSideLeft = objWall "leftWall" LeftSide (0, 0)
+
+-- | See 'objSideRight'.
+objSideTop :: ObjectSF
+objSideTop = objWall "topWall" TopSide (0, 0)
+
+-- | See 'objSideRight'.
+objSideBottom :: ObjectSF
+objSideBottom = objWall "bottomWall" BottomSide (0, gameHeight)
+
+-- | Generic wall builder, given a name, a side and its base
+-- position.
+objWall :: ObjectName -> Side -> Pos2D -> ObjectSF
+objWall name side pos = arr $ \(ObjectInput ci cs) ->
+ Object { objectName = name
+ , objectKind = Side side
+ , objectPos = pos
+ , objectVel = (0,0)
+ , canCauseCollisions = False
+ , collisionEnergy = 0
+ }
+
+-- * Auxiliary FRP stuff
+maybeToEvent :: Maybe a -> Event a
+maybeToEvent = maybe noEvent Event
+
+inertSF :: SF a b -> ListSF a b
+inertSF sf = ListSF (sf >>> arr (\o -> (o, False, [])))
+
+restartOn :: SF a b -> SF a (Event c) -> SF a b
+restartOn sf sfc = switch (sf &&& sfc)
+ (\_ -> restartOn sf sfc)
+
+spikeOn :: SF a Bool -> SF a (Event ())
+spikeOn sf = noEvent --> (sf >>> edge)
diff --git a/Experiments/splitballs/GameState.hs b/Experiments/splitballs/GameState.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/splitballs/GameState.hs
@@ -0,0 +1,36 @@
+-- | The state of the game during execution. It has two
+-- parts: general info (level, points, etc.) and
+-- the actual gameplay info (objects).
+--
+-- Because the game is always in some running state
+-- (there are no menus, etc.) we assume that there's
+-- always some gameplay info, even though it can be
+-- empty.
+module GameState where
+
+-- import FRP.Yampa as Yampa
+
+import Debug.Trace
+import Objects
+import FRP.Yampa (Time)
+
+-- | The running state is given by a bunch of 'Objects' and the current general
+-- 'GameInfo'. The latter contains info regarding the current level, the number
+-- of points, etc.
+--
+-- Different parts of the game deal with these data structures. It is
+-- therefore convenient to group them in subtrees, even if there's no
+-- substantial difference betweem them.
+data GameState = GameState
+ { gameObjects :: !Objects
+ , gameInfo :: !GameInfo
+ }
+
+-- | Initial (default) game state.
+neutralGameState :: GameState
+neutralGameState = GameState
+ { gameObjects = []
+ , gameInfo = GameInfo 0
+ }
+
+data GameInfo = GameInfo { gameTime :: Time }
diff --git a/Experiments/splitballs/Graphics/UI/Extra/SDL.hs b/Experiments/splitballs/Graphics/UI/Extra/SDL.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/splitballs/Graphics/UI/Extra/SDL.hs
@@ -0,0 +1,40 @@
+module Graphics.UI.Extra.SDL where
+
+import Data.IORef
+import Data.Maybe (isNothing)
+import Graphics.UI.SDL as SDL
+
+-- Auxiliary SDL stuff
+isEmptyEvent :: Event -> Bool
+isEmptyEvent SDL.NoEvent = True
+isEmptyEvent _ = False
+
+initializeTimeRef :: IO (IORef Int)
+initializeTimeRef = do
+ -- Weird shit I have to do to get accurate time!
+ timeRef <- newIORef (0 :: Int)
+ _ <- senseTimeRef timeRef
+ _ <- senseTimeRef timeRef
+ _ <- senseTimeRef timeRef
+ _ <- senseTimeRef timeRef
+
+ return timeRef
+
+senseTimeRef :: IORef Int -> IO Int
+senseTimeRef timeRef = do
+ -- Get time passed since SDL init
+ newTime <- fmap fromIntegral SDL.getTicks
+
+ -- Obtain time difference
+ dt <- updateTime timeRef newTime
+ return dt
+
+-- | Updates the time in an IO Ref and returns the time difference
+updateTime :: IORef Int -> Int -> IO Int
+updateTime timeRef newTime = do
+ previousTime <- readIORef timeRef
+ writeIORef timeRef newTime
+ return (newTime - previousTime)
+
+milisecsToSecs :: Int -> Double
+milisecsToSecs m = fromIntegral m / 1000
diff --git a/Experiments/splitballs/Input.hs b/Experiments/splitballs/Input.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/splitballs/Input.hs
@@ -0,0 +1,112 @@
+-- | Defines an abstraction for the game controller and the functions to read
+-- it.
+--
+-- Lower-level devices replicate the higher-level API, and should accomodate to
+-- it. Each device should:
+--
+-- - Upon initialisation, return any necessary information to poll it again.
+--
+-- - Update the controller with its own values upon sensing.
+--
+-- In this case, we only have one: mouse/keyboard combination.
+--
+module Input where
+
+-- External imports
+import Data.IORef
+import Graphics.UI.SDL as SDL
+
+-- Internal imports
+import Control.Extra.Monad
+import Graphics.UI.Extra.SDL
+
+-- * Game controller
+
+-- | Controller info at any given point.
+data Controller = Controller
+ { controllerPos :: (Double, Double)
+ , controllerClick :: Bool
+ , controllerStop :: Bool
+ , controllerPause :: Bool
+ , controllerExit :: Bool
+ , controllerFast :: Bool
+ , controllerSlow :: Bool
+ , controllerSuperSlow :: Bool
+ , controllerFullscreen :: Bool
+ }
+
+-- | Controller info at any given point, plus a pointer
+-- to poll the main device again. This is safe,
+-- since there is only one writer at a time (the device itself).
+newtype ControllerRef =
+ ControllerRef { controllerData :: (IORef Controller, Controller -> IO Controller) }
+
+-- * General API
+
+-- | Initialize the available input devices. This operation
+-- returns a reference to a controller, which enables
+-- getting its state as many times as necessary. It does
+-- not provide any information about its nature, abilities, etc.
+initializeInputDevices :: IO ControllerRef
+initializeInputDevices = do
+ nr <- newIORef defaultInfo
+ return $ ControllerRef (nr, sdlGetController)
+ where defaultInfo = Controller (0,0) False False False False False False False False
+
+-- | Sense from the controller, providing its current
+-- state. This should return a new Controller state
+-- if available, or the last one there was.
+--
+-- It is assumed that the sensing function is always
+-- callable, and that it knows how to update the
+-- Controller info if necessary.
+senseInput :: ControllerRef -> IO Controller
+senseInput (ControllerRef (cref, sensor)) =
+ modifyIORefIO cref sensor
+
+type ControllerDev = IO (Maybe (Controller -> IO Controller))
+
+-- * SDL API (mid-level)
+
+-- ** Sensing
+
+-- | Sense the SDL keyboard and mouse and update
+-- the controller. It only senses the mouse position,
+-- the primary mouse button, and the p key to pause
+-- the game.
+--
+-- We need a non-blocking controller-polling function.
+-- TODO: Check http://gameprogrammer.com/fastevents/fastevents1.html
+sdlGetController :: Controller -> IO Controller
+sdlGetController info =
+ foldLoopM info pollEvent (not.isEmptyEvent) ((return .) . handleEvent)
+
+handleEvent :: Controller -> SDL.Event -> Controller
+handleEvent c e =
+ case e of
+ MouseMotion x y _ _ -> c { controllerPos = (fromIntegral x, fromIntegral y)}
+ MouseButtonDown _ _ ButtonLeft -> c { controllerClick = True }
+ MouseButtonUp _ _ ButtonLeft -> c { controllerClick = False}
+ KeyUp (Keysym { symKey = SDLK_p }) -> c { controllerPause = not (controllerPause c) }
+ KeyUp (Keysym { symKey = SDLK_f }) -> c { controllerFullscreen = not (controllerFullscreen c) }
+ KeyDown (Keysym { symKey = SDLK_w }) -> c { controllerSuperSlow = True }
+ KeyUp (Keysym { symKey = SDLK_w }) -> c { controllerSuperSlow = False }
+ KeyDown (Keysym { symKey = SDLK_s }) -> c { controllerSlow = True }
+ KeyUp (Keysym { symKey = SDLK_s }) -> c { controllerSlow = False }
+ KeyDown (Keysym { symKey = SDLK_x }) -> c { controllerFast = True }
+ KeyUp (Keysym { symKey = SDLK_x }) -> c { controllerFast = False }
+ KeyDown (Keysym { symKey = SDLK_h }) -> c { controllerStop = True }
+ KeyUp (Keysym { symKey = SDLK_h }) -> c { controllerStop = False }
+ KeyDown (Keysym { symKey = SDLK_SPACE }) -> c { controllerClick = True }
+ KeyUp (Keysym { symKey = SDLK_SPACE }) -> c { controllerClick = False }
+ KeyDown (Keysym { symKey = SDLK_ESCAPE}) -> c { controllerExit = True }
+ _ -> c
+
+
+-- * Aux IOREf
+modifyIORefIO :: IORef a -> (a -> IO a) -> IO a
+modifyIORefIO ref modify = do
+ v <- readIORef ref
+ new <- modify v
+ writeIORef ref new
+ return new
diff --git a/Experiments/splitballs/Main.hs b/Experiments/splitballs/Main.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/splitballs/Main.hs
@@ -0,0 +1,43 @@
+import Control.Applicative
+import Control.Concurrent
+import Control.Monad
+import Control.Monad.IfElse
+import Data.IORef
+import Debug.Trace
+import FRP.Yampa as Yampa
+import Text.Printf
+
+import Game
+import Display
+import Input
+import Graphics.UI.Extra.SDL
+
+main :: IO ()
+main = do
+
+ initializeDisplay
+
+ timeRef <- initializeTimeRef
+ controllerRef <- initializeInputDevices
+ res <- loadResources
+
+ initGraphs res
+ reactimate (senseInput controllerRef)
+ (\_ -> do
+ -- Get clock and new input
+ mInput <- senseInput controllerRef
+ dtSecs <- senseTime timeRef mInput
+ -- trace ("Time : " ++ printf "%.5f" dtSecs) $
+ return (if controllerPause mInput then 0 else dtSecs, Just mInput)
+ )
+ (\_ (e,c) -> do render res e
+ return (controllerExit c)
+ )
+ (wholeGame &&& arr id)
+
+senseTime :: IORef Int -> Controller -> IO DTime
+senseTime timeRef = \mInput ->
+ let tt = if controllerSlow mInput then (/10) else id
+ tt1 = if controllerSuperSlow mInput then (/100) else tt
+ tt2 = if controllerFast mInput then (*10) else tt1
+ in (tt2 . milisecsToSecs) <$> senseTimeRef timeRef
diff --git a/Experiments/splitballs/ObjectSF.hs b/Experiments/splitballs/ObjectSF.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/splitballs/ObjectSF.hs
@@ -0,0 +1,44 @@
+-- | Objects as signal functions.
+--
+-- Live objects in the game take user input and the game universe
+-- and define their state in terms of that. They can remember what
+-- happened (see Yampa's Arrow combinators, which hide continuations),
+-- change their behaviour (see switches in Yampa).
+module ObjectSF where
+
+import FRP.Yampa
+
+import Objects
+import Input
+
+-- | Objects are defined as transformations that take 'ObjectInput' signals and
+-- return 'ObjectOutput' signals.
+type ObjectSF = SF ObjectInput Object
+
+-- | In order to determine its new output, an object needs to know the user's
+-- desires ('userInput'), whether there have been any collisions
+-- ('collisions').
+--
+-- The reason for depending on 'Collisions' is that objects may ``change''
+-- when hit (start moving in a different direction).
+data ObjectInput = ObjectInput
+ { userInput :: Controller
+ , collisions :: Collisions
+ }
+
+-- -- | What we can see about each live object at each time. It's a
+-- -- snapshot of the object.
+-- data ObjectOutput = ObjectOutput
+-- { outputObject :: Object -- ^ The object's state (position, shape, etc.).
+-- }
+
+-- -- | List of identifiable objects. Used to work with dynamic object
+-- -- collections.
+-- type ObjectSFs = IL ObjectSF
+
+-- extractObjects :: Functor f => SF (f ObjectOutput) (f Object)
+-- extractObjects = arr (fmap outputObject)
+--
+-- -- | A list of object outputs
+-- type ObjectOutputs = [ObjectOutput]
+--
diff --git a/Experiments/splitballs/Objects.hs b/Experiments/splitballs/Objects.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/splitballs/Objects.hs
@@ -0,0 +1,65 @@
+{-# LANGUAGE TypeSynonymInstances #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+-- | Game objects and collisions.
+module Objects where
+
+import Control.Arrow ((***))
+import FRP.Yampa.VectorSpace
+
+import qualified Physics.TwoDimensions.Collisions as C
+import Physics.TwoDimensions.Dimensions
+import Physics.TwoDimensions.PhysicalObjects
+import qualified Physics.TwoDimensions.PhysicalObjects as PO
+import Physics.TwoDimensions.Shapes
+
+type Collision = C.Collision ObjectName
+type Collisions = C.Collisions ObjectName
+
+-- * Objects
+
+type Objects = [Object]
+type ObjectName = String
+
+-- | Objects have logical properties (ID, kind, dead, hit), shape properties
+-- (kind), physical properties (kind, pos, vel, acc) and collision properties
+-- (hit, 'canCauseCollisions', energy, displaced).
+data Object = Object { objectName :: !ObjectName
+ , objectKind :: !ObjectKind
+ , objectPos :: !Pos2D
+ , objectVel :: !Vel2D
+ , canCauseCollisions :: !Bool
+ , collisionEnergy :: !Double
+ }
+ deriving (Show)
+
+-- | The kind of object and any size properties.
+data ObjectKind = Ball Double -- radius
+ | Side Side
+ deriving (Show,Eq)
+
+-- Partial function. Object has size.
+objectTopLevelCorner :: Object -> Pos2D
+objectTopLevelCorner object = objectPos object ^-^ half (objectSize object)
+ where half = let h = (/2) in (h *** h)
+
+-- Partial function!
+objectSize :: Object -> Size2D
+objectSize object = case objectKind object of
+ (Ball r) -> let w = 2*r in (w, w)
+
+instance PhysicalObject Object String Shape where
+ physObjectPos = objectPos
+ physObjectVel = objectVel
+ physObjectElas = collisionEnergy
+ physObjectShape = objShape
+ physObjectCollides = canCauseCollisions
+ physObjectId = objectName
+ physObjectUpdatePos = \o p -> o { objectPos = p }
+ physObjectUpdateVel = \o v -> o { objectVel = v }
+
+objShape :: Object -> Shape
+objShape obj = case objectKind obj of
+ Ball r -> Circle p r
+ Side s -> SemiPlane p s
+ where p = objectPos obj
diff --git a/Experiments/splitballs/Physics/TwoDimensions/Collisions.hs b/Experiments/splitballs/Physics/TwoDimensions/Collisions.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/splitballs/Physics/TwoDimensions/Collisions.hs
@@ -0,0 +1,141 @@
+{-# LANGUAGE FlexibleContexts #-}
+-- | A trivial collision subsystem.
+--
+-- Based on the physics module, it determines the side of collision
+-- between shapes.
+module Physics.TwoDimensions.Collisions where
+
+import Data.Extra.Num
+import Data.Maybe
+import FRP.Yampa.VectorSpace
+import Physics.TwoDimensions.Dimensions
+import Physics.TwoDimensions.PhysicalObjects
+import Physics.TwoDimensions.Shapes
+
+-- * Collision points
+data CollisionPoint = CollisionSide Side
+ | CollisionAngle Double
+
+-- | Calculates the collision side of a shape
+-- that collides against another.
+--
+-- PRE: the shapes do collide. Use 'overlapShape' to check.
+shapeCollisionPoint :: Shape -> Shape -> CollisionPoint
+shapeCollisionPoint (Circle p1 _) (Circle p2 _) =
+ -- | p1x =~ p2x && p1y > p2y = CollisionAngle (- pi / 2)
+ -- | p1x =~ p2x && p1y <= p2y = CollisionAngle (pi / 2)
+ -- | otherwise =
+ CollisionAngle angle
+ where (px,py) = p2 ^-^ p1
+ angle = atan2 py px
+shapeCollisionPoint (Circle _ _) (SemiPlane _ s2) = CollisionSide s2
+shapeCollisionPoint (SemiPlane _ s1) (Circle _ _ ) = CollisionSide (oppositeSide s1)
+shapeCollisionPoint (SemiPlane _ _) (SemiPlane _ s2) = CollisionSide s2
+-- * Collisions
+type Collisions k = [Collision k]
+
+-- | A collision is a list of objects that collided, plus their velocities as
+-- modified by the collision.
+--
+-- Take into account that the same object could take part in several
+-- simultaneous collitions, so these velocities should be added (per object).
+data Collision k = Collision
+ { collisionData :: [(k, Vel2D)] } -- ObjectId x Velocity
+ deriving Show
+
+-- | Detects a collision between one object and another.
+detectCollision :: (PhysicalObject o k Shape) => o -> o -> Maybe (Collision k)
+detectCollision obj1 obj2
+ | overlap obj1 obj2
+ = case (physObjectShape obj1, physObjectShape obj2) of
+ (Circle _ _, Circle _ _) ->
+ if vrn < 0
+ then Just response
+ else Nothing
+ _ -> Just response
+ | otherwise = Nothing
+
+ where response = collisionResponseObj obj1 obj2
+ colNormal = normalize (physObjectPos obj1 ^-^ physObjectPos obj2)
+ relativeV = physObjectVel obj1 ^-^ physObjectVel obj2
+ vrn = relativeV `dot` colNormal
+
+overlap :: PhysicalObject o k Shape => o -> o -> Bool
+overlap obj1 obj2 =
+ overlapShape (physObjectShape obj1) (physObjectShape obj2)
+
+collisionPoint :: PhysicalObject o k Shape => o -> o -> CollisionPoint
+collisionPoint obj1 obj2 =
+ shapeCollisionPoint (physObjectShape obj1) (physObjectShape obj2)
+
+collisionResponseObj :: PhysicalObject o k Shape => o -> o -> Collision k
+collisionResponseObj o1 o2 = Collision $
+ map objectToCollision [(o1, collisionPt, o2), (o2, collisionPt', o1)]
+ where collisionPt = collisionPoint o1 o2
+ collisionPt' = collisionPoint o2 o1
+ objectToCollision (o,pt,o') =
+ (physObjectId o,
+ correctVel (physObjectPos o) (physObjectPos o')
+ (physObjectVel o) (physObjectVel o')
+ pt (physObjectElas o))
+
+correctVel :: Pos2D -> Pos2D -> Vel2D -> Vel2D -> CollisionPoint -> Double -> Vel2D
+-- Specialised cases: just more optimal execution
+correctVel _p1 _p2 v1 _ _ 0 = v1
+-- Collision against a wall
+correctVel _p1 _p2 (v1x,v1y) _ (CollisionSide TopSide) e = (e * v1x, e * ensurePos v1y)
+correctVel _p1 _p2 (v1x,v1y) _ (CollisionSide BottomSide) e = (e * v1x, e * ensureNeg v1y)
+correctVel _p1 _p2 (v1x,v1y) _ (CollisionSide LeftSide) e = (e * ensurePos v1x, e * v1y)
+correctVel _p1 _p2 (v1x,v1y) _ (CollisionSide RightSide) e = (e * ensureNeg v1x, e * v1y)
+-- General case
+correctVel p1 p2 (v1x,v1y) (v2x, v2y) (CollisionAngle _) e = (v1x, v1y) ^+^ ((e * j) *^ colNormal)
+ where colNormal = normalize (p1 ^-^ p2)
+ relativeV = (v1x,v1y) ^-^ (v2x,v2y)
+ vrn = relativeV `dot` colNormal
+ j = (-1) *^ vrn / (colNormal `dot` colNormal)
+
+-- | Return the new velocity as changed by the collection of collisions.
+--
+-- HN 2014-09-07: New interface to collision detection.
+--
+-- The assumption is that collision detection happens globally and that the
+-- changed velocity is figured out for each object involved in a collision
+-- based on the properties of all objects involved in any specific interaction.
+-- That may not be how it works now, but the interface means it could work
+-- that way. Even more physical might be to figure out the impulsive force
+-- acting on each object.
+--
+-- However, the whole collision infrastructure should be revisited.
+--
+-- - Statefulness ("edge") might make it more robust.
+--
+-- - Think through how collision events are going to be communicated
+-- to the objects themselves. Maybe an input event is the natural
+-- thing to do. Except then we have to be careful to avoid switching
+-- again immediately after one switch.
+--
+-- - Should try to avoid n^2 checks. Maybe some kind of quad-trees?
+-- Maybe spawning a stateful collision detector when two objects are
+-- getting close? Cf. the old tail-gating approach.
+-- - Maybe a collision should also carry the identity of the object
+-- one collieded with to facilitate impl. of "inCollisionWith".
+--
+changedVelocity :: Eq n => n -> Collisions n -> Maybe Vel2D
+changedVelocity name cs =
+ case concatMap (filter ((== name) . fst) . collisionData) cs of
+ [] -> Nothing
+ -- vs -> Just (foldl (^+^) (0,0) (map snd vs))
+ (_, v') : _ -> Just v'
+
+-- | True if the velocity of the object has been changed by any collision.
+inCollision :: Eq n => n -> Collisions n -> Bool
+inCollision name cs = isJust (changedVelocity name cs)
+
+-- | True if the two objects are colliding with one another.
+inCollisionWith :: Eq n => n -> n -> Collisions n -> Bool
+inCollisionWith nm1 nm2 cs = any both cs
+ where
+ both (Collision nmvs) =
+ any ((== nm1) . fst) nmvs
+ && any ((== nm2) . fst) nmvs
+
diff --git a/Experiments/splitballs/Physics/TwoDimensions/Dimensions.hs b/Experiments/splitballs/Physics/TwoDimensions/Dimensions.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/splitballs/Physics/TwoDimensions/Dimensions.hs
@@ -0,0 +1,9 @@
+-- | Physical dimensions used all over the game. They are just type synonyms,
+-- but it's best to use meaningful names to make our type signatures more
+-- meaningful.
+module Physics.TwoDimensions.Dimensions where
+
+type Size2D = (Double, Double)
+type Pos2D = (Double, Double)
+type Vel2D = (Double, Double)
+type Acc2D = (Double, Double)
diff --git a/Experiments/splitballs/Physics/TwoDimensions/GameCollisions.hs b/Experiments/splitballs/Physics/TwoDimensions/GameCollisions.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/splitballs/Physics/TwoDimensions/GameCollisions.hs
@@ -0,0 +1,60 @@
+{-# LANGUAGE FlexibleContexts #-}
+-- | A very rudimentary collision system.
+--
+-- It compares every pair of objects, trying to determine if there is a
+-- collision between the two of them.
+--
+-- NOTE: In order to minimize the number of comparisons, only moving objects
+-- are tested (against every game object). That's only 2 objects right now
+-- (making it almost linear in complexity), but it could easily grow and become
+-- too slow.
+--
+module Physics.TwoDimensions.GameCollisions where
+
+import Data.Foldable
+import Prelude hiding (toList, concatMap)
+import Data.List hiding (toList, concatMap)
+import Data.Maybe
+import Physics.TwoDimensions.Collisions
+import qualified Physics.TwoDimensions.Collisions as C
+import Physics.TwoDimensions.PhysicalObjects
+import Physics.TwoDimensions.Shapes
+
+-- | Given a list of objects, it detects all the collisions between them.
+--
+-- Note: this is a simple n*m-complex algorithm, with n the
+-- number of objects and m the number of moving objects (right now,
+-- only 2).
+--
+detectCollisions :: Foldable t => (Eq n , PhysicalObject o n Shape) => t o -> Collisions n
+detectCollisions = detectCollisionsH
+ where detectCollisionsH objsT = flattened
+ where -- Eliminate empty collision sets
+ -- TODO: why is this really necessary?
+ flattened = filter (\(C.Collision n) -> not (null n)) collisions
+
+ -- Detect collisions between moving objects and any other objects
+ collisions = detectCollisions' objsT moving
+
+ -- Partition the object space between moving and static objects
+ (moving, _static) = partition physObjectCollides $ toList objsT
+
+-- | Detect collisions between each moving object and
+-- every other object.
+detectCollisions' :: (Foldable t, Foldable u) => (Eq n, PhysicalObject o n Shape) => t o -> u o -> [Collision n]
+detectCollisions' objsT ms = concatMap (detectCollisions'' objsT) ms
+
+-- | Detect collisions between one specific moving object and every existing
+-- object. Each collision is idependent of the rest (which is not necessarily
+-- what should happen, but since the transformed velocities are eventually
+-- added, there isn't much difference in the end).
+detectCollisions'' :: Foldable t => (Eq n, PhysicalObject o n Shape) => t o -> o -> [Collision n]
+detectCollisions'' objsT m = concatMap (detectCollisions''' m) (toList objsT)
+
+-- | Detect a possible collision between two objects. Uses the object's keys to
+-- distinguish them. Uses the basic 'Object'-based 'detectCollision' to
+-- determine whether the two objects do collide.
+detectCollisions''' :: (Eq n, PhysicalObject o n Shape) => o -> o -> [Collision n]
+detectCollisions''' m o
+ | physObjectId m == physObjectId o = [] -- Same object -> no collision
+ | otherwise = maybeToList (detectCollision m o)
diff --git a/Experiments/splitballs/Physics/TwoDimensions/PhysicalObjects.hs b/Experiments/splitballs/Physics/TwoDimensions/PhysicalObjects.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/splitballs/Physics/TwoDimensions/PhysicalObjects.hs
@@ -0,0 +1,16 @@
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE FunctionalDependencies #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+module Physics.TwoDimensions.PhysicalObjects where
+
+import Physics.TwoDimensions.Dimensions
+
+class Eq b => PhysicalObject a b c | a -> b, a -> c where
+ physObjectPos :: a -> Pos2D
+ physObjectVel :: a -> Vel2D
+ physObjectElas :: a -> Double
+ physObjectShape :: a -> c
+ physObjectCollides :: a -> Bool
+ physObjectId :: a -> b
+ physObjectUpdatePos :: a -> Pos2D -> a
+ physObjectUpdateVel :: a -> Vel2D -> a
diff --git a/Experiments/splitballs/Physics/TwoDimensions/Shapes.hs b/Experiments/splitballs/Physics/TwoDimensions/Shapes.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/splitballs/Physics/TwoDimensions/Shapes.hs
@@ -0,0 +1,45 @@
+-- | A very simple physics subsytem. It currently detects shape
+-- overlaps only, the actual physics movement is carried out
+-- in Yampa itself, as it is very simple using integrals and
+-- derivatives.
+module Physics.TwoDimensions.Shapes where
+
+import FRP.Yampa.VectorSpace
+import Physics.TwoDimensions.Dimensions
+
+-- | Side of a rectangle
+data Side = TopSide | BottomSide | LeftSide | RightSide
+ deriving (Eq,Show)
+
+-- | Opposite side
+--
+-- If A collides with B, the collision sides on
+-- A and B are always opposite.
+oppositeSide :: Side -> Side
+oppositeSide TopSide = BottomSide
+oppositeSide BottomSide = TopSide
+oppositeSide LeftSide = RightSide
+oppositeSide RightSide = LeftSide
+
+data Shape = -- Rectangle Pos2D Size2D -- A corner and the whole size
+ Circle Pos2D Double -- Position and radius
+ | SemiPlane Pos2D Side --
+
+-- | Detects if two shapes overlap.
+--
+-- Rectangles: overlap if projections on both axis overlap,
+-- which happens if x distance between centers is less than the sum
+-- of half the widths, and the analogous for y and the heights.
+
+overlapShape :: Shape -> Shape -> Bool
+overlapShape (Circle p1 s1) (Circle p2 s2) = (dist - (s1 + s2)) < sigma
+ where (dx, dy) = p2 ^-^ p1
+ dist = sqrt (dx**2 + dy**2)
+ sigma = 1
+overlapShape (Circle (p1x,p1y) s1) (SemiPlane (px,py) side) = case side of
+ LeftSide -> p1x - s1 <= px
+ RightSide -> p1x + s1 >= px
+ TopSide -> p1y - s1 <= py
+ BottomSide -> p1y + s1 >= py
+overlapShape s@(SemiPlane _ _) c@(Circle _ _) = overlapShape c s
+overlapShape _ _ = False -- Not really, it's just that we don't care
diff --git a/Experiments/splitballs/Resources.hs b/Experiments/splitballs/Resources.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/splitballs/Resources.hs
@@ -0,0 +1,10 @@
+module Resources where
+
+import qualified Graphics.UI.SDL.TTF as TTF
+
+-- import Game.Audio
+
+data Resources = Resources
+ { resFont :: TTF.Font
+ , miniFont :: TTF.Font
+ }
diff --git a/Experiments/splitting-boxes/Main.hs b/Experiments/splitting-boxes/Main.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/splitting-boxes/Main.hs
@@ -0,0 +1,156 @@
+{-# LANGUAGE Arrows #-}
+import Data.IORef
+import Data.List
+import Debug.Trace
+import FRP.Yampa as Yampa
+import FRP.Yampa.Switches as Yampa
+import Graphics.UI.SDL as SDL
+
+width = 640
+height = 480
+
+main = do
+ timeRef <- newIORef (0 :: Int)
+ reactimate initGraphs
+ (\_ -> do
+ dtSecs <- yampaSDLTimeSense timeRef
+ return (dtSecs, Nothing))
+ (\_ e -> display e >> return False)
+ mainSF
+
+-- | Updates the time in an IO Ref and returns the time difference
+updateTime :: IORef Int -> Int -> IO Int
+updateTime timeRef newTime = do
+ previousTime <- readIORef timeRef
+ writeIORef timeRef newTime
+ return (newTime - previousTime)
+
+yampaSDLTimeSense :: IORef Int -> IO Yampa.DTime
+yampaSDLTimeSense timeRef = do
+ -- Get time passed since SDL init
+ newTime <- fmap fromIntegral SDL.getTicks
+
+ -- Obtain time difference
+ dt <- updateTime timeRef newTime
+ let dtSecs = fromIntegral dt / 1000
+ return dtSecs
+
+initGraphs :: IO ()
+initGraphs = do
+ -- Initialise SDL
+ SDL.init [InitVideo]
+
+ -- Create window
+ screen <- setVideoMode width height 16 [SWSurface]
+ setCaption "Test" ""
+
+display :: [(Double,Double)] -> IO()
+display xs = do
+ -- Obtain surface
+ screen <- getVideoSurface
+
+ -- Paint screen green
+ let format = surfaceGetPixelFormat screen
+ green <- mapRGB format 0 0xFF 0
+ fillRect screen Nothing green
+
+ -- Paint small red square, at an angle 'angle' with respect to the center
+ red <- mapRGB format 0xFF 0 0
+ let side = 10
+ let paintSquare (x,y) =
+ fillRect screen (Just (Rect (round x) (round y) side side)) red
+
+ mapM_ paintSquare xs
+
+ -- Double buffering
+ SDL.flip screen
+
+ SDL.delay 10
+
+-- | Main animation
+mainSF :: SF () [(Double, Double)]
+mainSF = dlSwitch initialList
+
+-- | A list of position-producing forking-dying SFs
+initialList :: [ListSF () (Double, Double)]
+initialList = [ inCircles (320, 240) ]
+
+-- | Describe a movement in circles, forking every few samples.
+inCircles :: (Double, Double) -> ListSF () (Double, Double)
+inCircles (baseX, baseY) = ListSF $ proc () -> do
+ t <- localTime -< ()
+ let radius = 30
+ x = baseX + (cos t * radius)
+ y = baseY + (sin t * radius)
+
+ -- OffSpring
+ split <- isEvent ^<< spike 300 -< ()
+ let offspring = if split
+ then [inCircles (y*2, x/2), inCircles (x/2, y*2)]
+ else []
+
+ -- Time to die?
+ die <- isEvent ^<< spike 350 -< ()
+
+ returnA -< ((x,y), die, offspring)
+
+ -- () <- arr id -< trace ( "Time : " ++ show t
+ -- ++ " mod: " ++ show (round t `mod` 10)
+ -- ++ " s: " ++ show split
+ -- )
+ -- ()
+
+-- | Produce a spike every few samples.
+spike :: Int -> SF () (Yampa.Event ())
+spike m = spikeBool m >>> edge
+ where spikeBool m = resetCounter m >>> arr (== 0)
+
+-- | Create a decreasing counter that is reset to the starting value when it
+-- reaches 0.
+resetCounter :: Int -> SF () Int
+resetCounter m = loopPre m $ arr (snd >>> decR m >>> dup)
+ where decR m n = if n == 0 then m else n - 1
+ dup x = (x, x)
+
+-- Version of list splitting that works in traditional Yampa
+-- inCirclesL' ips = inCirclesL ips >>> arr (map fst)
+--
+-- inCirclesL :: [SF () ((Double, Double), Bool)]
+-- -> SF () [((Double, Double), Bool)]
+-- inCirclesL ips = dpSwitchB ips evProd addToList
+--
+-- where
+-- evProd :: SF ((), [((Double, Double), Bool)]) (Yampa.Event [(Double, Double)])
+-- evProd = noEvent --> arr (snd >>> splitBalls)
+--
+-- initialList = [ inCircles (320, 240) ]
+-- initialList' = [ inCircles' (320, 240) ]
+--
+-- addToList :: [SF () ((Double, Double), Bool)]
+-- -> [(Double, Double)]
+-- -> SF () [((Double, Double), Bool)]
+-- addToList sfs ips = trace ("Adding new circles: " ++ show ips)
+-- $ inCirclesL (sfs ++ map inCircles ips)
+--
+-- splitBalls :: [((Double, Double), Bool)] -> Yampa.Event [(Double, Double)]
+-- splitBalls ps
+-- | null ls = noEvent
+-- | otherwise = Yampa.Event ls
+-- where ls = [ (y-20, x+20) | ((x,y),True) <- ps ]
+--
+-- inCircles :: (Double, Double) -> SF () ((Double, Double), Bool)
+-- inCircles (baseX, baseY) = proc () -> do
+-- t <- localTime -< ()
+-- let radius = 30
+-- x = baseX + (cos t * radius)
+-- y = baseY + (sin t * radius)
+--
+-- split <- noEvent --> spike 100 -< ()
+--
+-- () <- arr id -< trace ( "Time : " ++ show t
+-- ++ " mod: " ++ show (round t `mod` 10)
+-- ++ " s: " ++ show split
+-- )
+-- ()
+--
+-- returnA -< ((x,y), isEvent split)
diff --git a/Experiments/stickyarrowup/Main.hs b/Experiments/stickyarrowup/Main.hs
new file mode 100644
--- /dev/null
+++ b/Experiments/stickyarrowup/Main.hs
@@ -0,0 +1,81 @@
+{-# LANGUAGE Arrows #-}
+import Graphics.UI.SDL as SDL
+import Graphics.UI.SDL.Primitives as SDL
+import FRP.Yampa as Yampa
+import Data.IORef
+import Debug.Trace
+
+width = 640
+height = 480
+
+main = do
+ timeRef <- newIORef (0 :: Int)
+ reactimate initGraphs
+ (\_ -> do
+ dtSecs <- yampaSDLTimeSense timeRef
+ return (dtSecs, Nothing))
+ (\_ e -> display e >> return False)
+ (fire (fromIntegral height / 2) (-10))
+
+-- | Updates the time in an IO Ref and returns the time difference
+updateTime :: IORef Int -> Int -> IO Int
+updateTime timeRef newTime = do
+ previousTime <- readIORef timeRef
+ writeIORef timeRef newTime
+ return (newTime - previousTime)
+
+yampaSDLTimeSense :: IORef Int -> IO Yampa.DTime
+yampaSDLTimeSense timeRef = do
+ -- Get time passed since SDL init
+ newTime <- fmap fromIntegral SDL.getTicks
+
+ -- Obtain time difference
+ dt <- updateTime timeRef newTime
+ let dtSecs = fromIntegral dt / 100
+ return dtSecs
+
+initGraphs :: IO ()
+initGraphs = do
+ -- Initialise SDL
+ SDL.init [InitVideo]
+
+ -- Create window
+ screen <- setVideoMode width height 16 [SWSurface]
+ setCaption "Test" ""
+
+display :: (Double, Double) -> IO()
+display (boxY0,boxY) = do
+ -- Obtain surface
+ screen <- getVideoSurface
+
+ -- Paint screen green
+ let format = surfaceGetPixelFormat screen
+ green <- mapRGB format 0 0xFF 0
+ fillRect screen Nothing green
+
+ -- Paint small red square, at an angle 'angle' with respect to the center
+ red <- mapRGB format 0xFF 0xFF 0
+ let x = fromIntegral $ width `div` 2
+ y0 = round boxY0
+ y = round boxY
+ vLine screen x y0 y red
+
+ -- Double buffering
+ SDL.flip screen
+
+rising :: Double -> Double -> SF () (Double, Double)
+rising y0 v0 = proc () -> do
+ y <- (y0+) ^<< integral -< v0
+ returnA -< (y0, y)
+
+fire :: Double -> Double -> SF () (Double, Double)
+fire y vy = switch (rising y vy >>> (Yampa.identity &&& hitCeiling))
+ (\(y0, yn) -> switch (constant (y0, yn) &&& after 10 ())
+ (\_ -> fire y vy))
+
+hitCeiling :: SF (Double, Double) (Yampa.Event (Double, Double))
+hitCeiling = arr (\(y0,y) ->
+ let boxTop = y
+ in if boxTop < 0
+ then Yampa.Event (y0, y)
+ else Yampa.NoEvent)
diff --git a/LICENSE b/LICENSE
new file mode 100644
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,674 @@
+ GNU GENERAL PUBLIC LICENSE
+ Version 3, 29 June 2007
+
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+or that patent license was granted, prior to 28 March 2007.
+
+ Nothing in this License shall be construed as excluding or limiting
+any implied license or other defenses to infringement that may
+otherwise be available to you under applicable patent law.
+
+ 12. No Surrender of Others' Freedom.
+
+ If conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
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+not convey it at all. For example, if you agree to terms that obligate you
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+License would be to refrain entirely from conveying the Program.
+
+ 13. Use with the GNU Affero General Public License.
+
+ Notwithstanding any other provision of this License, you have
+permission to link or combine any covered work with a work licensed
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+
+ 14. Revised Versions of this License.
+
+ The Free Software Foundation may publish revised and/or new versions of
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+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+ Each version is given a distinguishing version number. If the
+Program specifies that a certain numbered version of the GNU General
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+option of following the terms and conditions either of that numbered
+version or of any later version published by the Free Software
+Foundation. If the Program does not specify a version number of the
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+by the Free Software Foundation.
+
+ If the Program specifies that a proxy can decide which future
+versions of the GNU General Public License can be used, that proxy's
+public statement of acceptance of a version permanently authorizes you
+to choose that version for the Program.
+
+ Later license versions may give you additional or different
+permissions. However, no additional obligations are imposed on any
+author or copyright holder as a result of your choosing to follow a
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+
+ 15. Disclaimer of Warranty.
+
+ THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
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+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
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+ 16. Limitation of Liability.
+
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+
+ 17. Interpretation of Sections 15 and 16.
+
+ If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+ END OF TERMS AND CONDITIONS
+
+ How to Apply These Terms to Your New Programs
+
+ If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+ To do so, attach the following notices to the program. It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+
+ Copyright (C)
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see .
+
+Also add information on how to contact you by electronic and paper mail.
+
+ If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+ Copyright (C)
+ This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+ This is free software, and you are welcome to redistribute it
+ under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License. Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+ You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+.
+
+ The GNU General Public License does not permit incorporating your program
+into proprietary programs. If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library. If this is what you want to do, use the GNU Lesser General
+Public License instead of this License. But first, please read
+.
diff --git a/Setup.hs b/Setup.hs
new file mode 100644
--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain
diff --git a/data/lacuna.ttf b/data/lacuna.ttf
new file mode 100644
Binary files /dev/null and b/data/lacuna.ttf differ
diff --git a/pang-a-lambda.cabal b/pang-a-lambda.cabal
new file mode 100644
--- /dev/null
+++ b/pang-a-lambda.cabal
@@ -0,0 +1,219 @@
+-- Initial pang-a-lambda.cabal generated by cabal init. For further
+-- documentation, see http://haskell.org/cabal/users-guide/
+
+name: pang-a-lambda
+version: 0.2.0.0
+synopsis: A super-pang clone
+description: An FRP implementation of superpang
+license: GPL-3
+license-file: LICENSE
+author: Ivan Perez
+maintainer: ivan.perez@keera.co.uk
+-- copyright:
+category: Game
+build-type: Simple
+-- extra-source-files:
+cabal-version: >=1.16
+data-files: data/*.ttf
+
+Flag experiments
+ Default: False
+ Description: Compile experimental demos
+
+executable pang-a-lambda-dumbplayer
+ main-is: Main.hs
+ -- other-modules:
+ other-extensions: Arrows
+ build-depends: base >=4.6 && <4.9, SDL, SDL-gfx, Yampa
+ hs-source-dirs: Experiments/dumbplayer/
+ default-language: Haskell2010
+ if !flag(experiments)
+ buildable: False
+
+executable pang-a-lambda-arrowup
+ main-is: Main.hs
+ -- other-modules:
+ other-extensions: Arrows
+ build-depends: base >=4.6 && <4.9, SDL, SDL-gfx, Yampa
+ hs-source-dirs: Experiments/arrowup/
+ default-language: Haskell2010
+ if !flag(experiments)
+ buildable: False
+
+executable pang-a-lambda-stickyarrow
+ main-is: Main.hs
+ -- other-modules:
+ other-extensions: Arrows
+ build-depends: base >=4.6 && <4.9, SDL, SDL-gfx, Yampa
+ hs-source-dirs: Experiments/stickyarrowup/
+ default-language: Haskell2010
+ if !flag(experiments)
+ buildable: False
+
+executable pang-a-lambda-player
+ main-is: Main.hs
+ -- other-modules:
+ other-extensions: Arrows
+ build-depends: base >=4.6 && <4.9, SDL, SDL-gfx, Yampa
+ hs-source-dirs: Experiments/player/
+ default-language: Haskell2010
+ if !flag(experiments)
+ buildable: False
+
+executable pang-a-lambda-physics
+ build-depends: base >=4.6 && <5,
+ bytestring,
+ containers -any,
+ IfElse -any,
+ mtl -any,
+ transformers >=0.3 && <0.5,
+ Yampa >=0.9.6 && <0.11,
+
+ SDL -any,
+ SDL-gfx -any,
+ SDL-ttf -any
+
+ main-is: Main.hs
+ hs-source-dirs: Experiments/collisions
+ other-modules:
+ -- Game specific
+ Constants
+ Debug
+ Display
+ Game
+ GameState
+ Input
+ Objects
+ ObjectSF
+ Resources
+
+ -- General modules
+ Control.Extra.Monad
+ Data.Extra.Num
+ Data.Extra.VectorSpace
+ Data.IdentityList
+ Graphics.UI.Extra.SDL
+ Physics.TwoDimensions.Collisions
+ Physics.TwoDimensions.Dimensions
+ Physics.TwoDimensions.GameCollisions
+ Physics.TwoDimensions.PhysicalObjects
+ Physics.TwoDimensions.Shapes
+ default-language: Haskell2010
+ if !flag(experiments)
+ buildable: False
+
+executable pang-a-lambda-circlingboxes
+ main-is: Main.hs
+ -- other-modules:
+ other-extensions: Arrows
+ build-depends: base >=4.6 && <4.9, SDL, Yampa
+ hs-source-dirs: Experiments/circling-boxes/
+ default-language: Haskell2010
+ if !flag(experiments)
+ buildable: False
+
+executable pang-a-lambda-splittingboxes
+ main-is: Main.hs
+ -- other-modules:
+ other-extensions: Arrows
+ build-depends: base >=4.6 && <4.9, SDL, Yampa
+ hs-source-dirs: Experiments/splitting-boxes/
+ default-language: Haskell2010
+ if !flag(experiments)
+ buildable: False
+
+executable pang-a-lambda-split
+ main-is: Main.hs
+ -- other-modules:
+ other-extensions: Arrows
+ build-depends: base >=4.6 && <4.9, SDL, Yampa
+ hs-source-dirs: Experiments/split/
+ default-language: Haskell2010
+ if !flag(experiments)
+ buildable: False
+
+executable pang-a-lambda-splitballs
+ build-depends: base >=4.6 && <5,
+ bytestring,
+ containers -any,
+ IfElse -any,
+ mtl -any,
+ transformers >=0.3 && <0.5,
+ Yampa >=0.9.6 && <0.11,
+
+ SDL -any,
+ SDL-gfx -any,
+ SDL-ttf -any
+
+ main-is: Main.hs
+ hs-source-dirs: Experiments/splitballs/
+ other-modules:
+ -- Game specific
+ Constants
+ Debug
+ Display
+ Game
+ GameState
+ Input
+ Objects
+ ObjectSF
+ Resources
+
+ -- General modules
+ Control.Extra.Monad
+ Data.Extra.Num
+ Data.Extra.VectorSpace
+ Graphics.UI.Extra.SDL
+ Physics.TwoDimensions.Collisions
+ Physics.TwoDimensions.Dimensions
+ Physics.TwoDimensions.GameCollisions
+ Physics.TwoDimensions.PhysicalObjects
+ Physics.TwoDimensions.Shapes
+ default-language: Haskell2010
+ if !flag(experiments)
+ buildable: False
+
+executable pang-a-lambda
+ build-depends: base >=4.6 && <5,
+ bytestring,
+ containers -any,
+ IfElse -any,
+ mtl -any,
+ transformers >=0.3 && <0.5,
+ Yampa >=0.9.6 && <0.11,
+
+ SDL -any,
+ SDL-gfx -any,
+ SDL-ttf -any
+ default-language: Haskell2010
+
+ main-is: Main.hs
+ hs-source-dirs: src/
+ ghc-options: -Wall
+ other-modules:
+ -- Game specific
+ Constants
+ Collisions
+ Debug
+ Display
+ Game
+ GameState
+ Input
+ Objects
+ Objects.Walls
+ ObjectSF
+ Resources
+
+ -- General modules
+ Control.Extra.Monad
+ Data.Extra.IORef
+ Data.Extra.Num
+ Data.Extra.Ord
+ Data.Extra.VectorSpace
+ FRP.Yampa.Extra
+ Graphics.UI.Extra.SDL
+ Physics.TwoDimensions.Collisions
+ Physics.TwoDimensions.Dimensions
+ Physics.TwoDimensions.GameCollisions
+ Physics.TwoDimensions.PhysicalObjects
+ Physics.TwoDimensions.Shapes
diff --git a/src/Collisions.hs b/src/Collisions.hs
new file mode 100644
--- /dev/null
+++ b/src/Collisions.hs
@@ -0,0 +1,125 @@
+-- Copyright (c) 2011 - All rights reserved - Keera Studios
+module Collisions where
+
+import Control.Applicative
+import Control.Arrow
+import Data.Maybe
+
+import Physics.TwoDimensions.Dimensions
+import FRP.Yampa.VectorSpace
+import Shapes
+import Data ( pointX, rotateRespect, unrotateRespect
+ , minimumWith, swap
+ )
+
+circleAABBOverlap :: Circle -> AABB -> Bool
+circleAABBOverlap c@(cp,cr) (rp, rs) =
+ circleAABBOverlap' ((0,0), cr) (rp ^-^ cp, rs)
+
+circleAABBOverlap' :: Circle -> AABB -> Bool
+circleAABBOverlap' ((p1x,p1y),r1) (p2@(p2x, p2y), s2@(w2, h2)) =
+ overlapX && overlapY && overlapP11 && overlapP12 && overlapP21 && overlapP22
+ where -- Square coordinates
+ p211@(p211x, p211y) = p2 ^-^ s2
+ p212@(p212x, p212y) = p2 ^+^ (-w2, h2)
+ p221@(p221x, p221y) = p2 ^+^ (w2, -h2)
+ p222@(p222x, p222y) = p2 ^+^ s2
+
+ -- Horizontal projection overlap
+ overlapX = (-r1, r1) `overlapSegment` (p2x - w2, p2x + w2)
+ overlapY = (-r1, r1) `overlapSegment` (p2y - h2, p2y + h2)
+
+ rectangleVertices = [p211, p212, p221, p222]
+
+ rotatedP211 = map (fst.rotateRespect p211) rectangleVertices
+ rotatedP212 = map (fst.rotateRespect p212) rectangleVertices
+ rotatedP221 = map (fst.rotateRespect p221) rectangleVertices
+ rotatedP222 = map (fst.rotateRespect p222) rectangleVertices
+
+ projection ps = (minimum ps, maximum ps)
+
+ overlapP11 = (-r1, r1) `overlapSegment` projection rotatedP211
+ overlapP12 = (-r1, r1) `overlapSegment` projection rotatedP212
+ overlapP21 = (-r1, r1) `overlapSegment` projection rotatedP221
+ overlapP22 = (-r1, r1) `overlapSegment` projection rotatedP222
+
+ overlapSegment (x01,x02) (x11, x12) = min x02 x12 > max x01 x11
+
+-- * Colision detection
+responseCircleAABB :: Circle -> AABB -> Maybe Pos2D
+responseCircleAABB c@(cp,cr) (rp, rs) =
+ responseCircleAABB' ((0,0), cr) (rp ^-^ cp, rs)
+
+responseCircleAABB' :: Circle -> AABB -> Maybe Pos2D
+responseCircleAABB' ((p1x,p1y),r1) (p2@(p2x, p2y), s2@(w2, h2))
+ | all isJust overlaps
+ = (Just . snd) $ minimumWith (abs.fst) $ map fromJust overlaps
+ | otherwise
+ = Nothing
+
+ where overlaps = [ overlapX, overlapY
+ , overlapP11, overlapP12
+ , overlapP21, overlapP22
+ ]
+
+ -- Square coordinates
+ p211@(p211x, p211y) = p2 ^-^ s2
+ p212@(p212x, p212y) = p2 ^+^ (-w2, h2)
+ p221@(p221x, p221y) = p2 ^+^ (w2, -h2)
+ p222@(p222x, p222y) = p2 ^+^ s2
+
+ -- Horizontal projection overlap
+ overlapX = (pointX &&& id) <$> (-r1, r1) `overlapSegment` (p2x - w2, p2x + w2)
+ overlapY = (pointX &&& swap) <$> (-r1, r1) `overlapSegment` (p2y - h2, p2y + h2)
+
+ rectangleVertices = [p211, p212, p221, p222]
+
+ rotatedP211 = map (rotateRespect p211) rectangleVertices
+ rotatedP212 = map (rotateRespect p212) rectangleVertices
+ rotatedP221 = map (rotateRespect p221) rectangleVertices
+ rotatedP222 = map (rotateRespect p222) rectangleVertices
+
+ xProjection = (minimum &&& maximum) . map pointX
+
+ circleOverlaps = overlapSegment (-r1, r1)
+
+ overlapP11 = (pointX &&& unrotateRespect p211) <$> circleOverlaps (xProjection rotatedP211)
+ overlapP12 = (pointX &&& unrotateRespect p212) <$> circleOverlaps (xProjection rotatedP212)
+ overlapP21 = (pointX &&& unrotateRespect p221) <$> circleOverlaps (xProjection rotatedP221)
+ overlapP22 = (pointX &&& unrotateRespect p222) <$> circleOverlaps (xProjection rotatedP222)
+
+ overlapSegment (x01,x02) (x11, x12)
+ | segmentLength' > 0 = Just (segmentLength, 0)
+ | otherwise = Nothing
+ where segmentLength = if x01 < x11 then -segmentLength' else segmentLength'
+ segmentLength' = if segmentLength'' == 0 then 1 else segmentLength''
+ segmentLength'' = min x02 x12 - max x01 x11
+
+responseAABB2 :: AABB -> AABB -> Maybe Pos2D
+responseAABB2 (pos1, size1) (pos2, size2)
+ | overlap && overlapx > overlapy = Just cy
+ | overlap && overlapy > overlapx = Just cx
+ | overlap = Just (cx ^+^ cy)
+ | otherwise = Nothing
+ where (x1,y1) = pos1
+ (w1,h1) = size1
+ (x2,y2) = pos2
+ (w2,h2) = size2
+ toRight = x1 > x2
+ toLeft = x1 < x2
+ above = y1 < y2
+ below = y1 > y2
+ overlapx = max 0 (w1 + w2 - abs (x1 - x2))
+ overlapy = max 0 (h1 + h2 - abs (y1 - y2))
+ overlap = overlapx > 0 && overlapy > 0
+ cx = if toRight then (overlapx, 0) else (-overlapx, 0)
+ cy = if above then (0, -overlapy) else (0, overlapy)
+ (x1,y1) ^+^ (x2,y2) = (x1+x2, y1+y2)
+
+overlapsAABB2 :: AABB -> AABB -> Bool
+overlapsAABB2 (pos1, size1) (pos2, size2) =
+ abs (x1 - x2) < w1 + w2 && abs (y1 - y2) < h1 + h2
+ where (x1,y1) = pos1
+ (w1,h1) = size1
+ (x2,y2) = pos2
+ (w2,h2) = size2
diff --git a/src/Constants.hs b/src/Constants.hs
new file mode 100644
--- /dev/null
+++ b/src/Constants.hs
@@ -0,0 +1,103 @@
+module Constants where
+
+import Data.Word
+import Graphics.UI.SDL as SDL
+
+gameName :: String
+gameName = "Break-a-ball"
+
+width :: Double
+width = 1024
+height :: Double
+height = 600
+
+gameWidth :: Double
+gameWidth = width
+
+gameHeight :: Double
+gameHeight = height
+
+-- Energy transmission between objects in collisions
+velTrans :: Double
+velTrans = 1.00
+
+-- Max speed
+maxVNorm :: Double -> Double
+maxVNorm n
+ | n >= 100 = 800
+ | n >= 50 = 733
+ | n >= 25 = 666
+ | otherwise = 600
+
+ballWidth, ballHeight :: Double
+ballWidth = 100
+ballHeight = 100
+
+ballMargin :: Double
+ballMargin = 3
+
+ballSize :: Integral a => a
+ballSize = 25
+
+-- Colors
+fontColor :: SDL.Color
+fontColor = SDL.Color 94 86 91
+
+ballColor :: Word32
+ballColor = 0xDD875FFF
+
+velColor :: Word32
+velColor = 0xCCBBFFFF
+
+playerWidth :: Double
+playerWidth = 30
+
+playerHeight :: Double
+playerHeight = 80
+
+fireColor :: Word32
+fireColor = 0xFFDDC34F
+
+playerRightColor :: Word32
+playerRightColor = 0xFFD2D454
+
+playerLeftColor :: Word32
+playerLeftColor = 0xFFB2D454
+
+playerStandColor :: Word32
+playerStandColor = 0xFFE5D454
+
+playerBlinkRightColor :: Word32
+playerBlinkRightColor = 0x88D2D454
+
+playerBlinkLeftColor :: Word32
+playerBlinkLeftColor = 0x88B2D454
+
+playerBlinkStandColor :: Word32
+playerBlinkStandColor = 0x88F2D454
+
+backgroundColor :: Word32
+backgroundColor = 0x88EDE9CB
+
+blockColor :: Word32
+blockColor = 0xFF85AABC
+
+playerSpeed :: Double
+playerSpeed = 200
+
+fireSpeed :: Double
+fireSpeed = 400
+
+initialLives :: Int
+initialLives = 5
+
+-- Debugging collisions
+
+collisionDebugColor :: Word32
+collisionDebugColor = 0x88D2D4FF
+
+collisionDebugThickness :: Num a => a
+collisionDebugThickness = 3
+
+debugCollisions :: Bool
+debugCollisions = False
diff --git a/src/Control/Extra/Monad.hs b/src/Control/Extra/Monad.hs
new file mode 100644
--- /dev/null
+++ b/src/Control/Extra/Monad.hs
@@ -0,0 +1,19 @@
+module Control.Extra.Monad where
+
+import Control.Monad
+
+whileLoopM :: Monad m => m a -> (a -> Bool) -> (a -> m ()) -> m ()
+whileLoopM val cond act = r'
+ where r' = do v <- val
+ when (cond v) $ do
+ act v
+ whileLoopM val cond act
+
+foldLoopM :: Monad m => a -> m b -> (b -> Bool) -> (a -> b -> m a) -> m a
+foldLoopM val sense cond act = r'
+ where r' = do s <- sense
+ if cond s
+ then do
+ val' <- act val s
+ foldLoopM val' sense cond act
+ else return val
diff --git a/src/Data/Extra/IORef.hs b/src/Data/Extra/IORef.hs
new file mode 100644
--- /dev/null
+++ b/src/Data/Extra/IORef.hs
@@ -0,0 +1,12 @@
+
+module Data.Extra.IORef where
+
+import Data.IORef
+
+-- * Aux IOREf
+modifyIORefIO :: IORef a -> (a -> IO a) -> IO a
+modifyIORefIO ref modify = do
+ v <- readIORef ref
+ new <- modify v
+ writeIORef ref new
+ return new
diff --git a/src/Data/Extra/Num.hs b/src/Data/Extra/Num.hs
new file mode 100644
--- /dev/null
+++ b/src/Data/Extra/Num.hs
@@ -0,0 +1,20 @@
+module Data.Extra.Num where
+
+ensurePos :: (Eq a, Num a) => a -> a
+ensurePos e = if signum e == (-1) then negate e else e
+
+ensureNeg :: (Eq a, Num a) => a -> a
+ensureNeg e = if signum e == 1 then negate e else e
+
+class Similar a where
+ sigma :: a -- margin of error
+
+instance Similar Float where
+ sigma = 0.01
+
+instance Similar Double where
+ sigma = 0.01
+
+(=~) :: (Num a, Ord a, Similar a) => a -> a -> Bool
+x =~ y = abs (x - y) < sigma
+
diff --git a/src/Data/Extra/Ord.hs b/src/Data/Extra/Ord.hs
new file mode 100644
--- /dev/null
+++ b/src/Data/Extra/Ord.hs
@@ -0,0 +1,6 @@
+module Data.Extra.Ord where
+
+inRange :: Ord a => (a, a) -> a -> a
+inRange (mn, mx) n | n < mn = mn
+ | n > mx = mx
+ | otherwise = n
diff --git a/src/Data/Extra/VectorSpace.hs b/src/Data/Extra/VectorSpace.hs
new file mode 100644
--- /dev/null
+++ b/src/Data/Extra/VectorSpace.hs
@@ -0,0 +1,6 @@
+module Data.Extra.VectorSpace where
+
+import FRP.Yampa.VectorSpace
+
+limitNorm :: (Ord s, VectorSpace v s) => v -> s -> v
+limitNorm v mn = if norm v > mn then mn *^ normalize v else v
diff --git a/src/Debug.hs b/src/Debug.hs
new file mode 100644
--- /dev/null
+++ b/src/Debug.hs
@@ -0,0 +1,8 @@
+module Debug where
+
+import Control.Monad (when, void)
+
+import Constants
+
+debug :: Bool -> String -> IO ()
+debug b msg = when b $ putStrLn msg
diff --git a/src/Display.hs b/src/Display.hs
new file mode 100644
--- /dev/null
+++ b/src/Display.hs
@@ -0,0 +1,229 @@
+{-# OPTIONS_GHC -fno-warn-unused-do-bind #-}
+module Display where
+
+import Control.Arrow ((***))
+import Control.Monad
+import Data.Maybe (fromJust)
+import FRP.Yampa.VectorSpace
+import Graphics.UI.SDL as SDL
+import qualified Graphics.UI.SDL.Primitives as SDLP
+import qualified Graphics.UI.SDL.TTF as TTF
+import Graphics.UI.Extra.SDL as SDL
+import Text.Printf
+
+import Constants
+import GameState
+import Objects
+import Resources
+import Physics.TwoDimensions.Shapes
+
+-- | Ad-hoc resource loading
+-- This function is ad-hoc in two senses: first, because it
+-- has the paths to the files hard-coded inside. And second,
+-- because it loads the specific resources that are needed,
+-- so it's not a general, parameterised, scalable solution.
+--
+loadResources :: IO Resources
+loadResources = do
+ -- Font initialization
+ _ <- TTF.init
+
+ -- Load the fonts we need
+ let gameFont = "data/lacuna.ttf"
+ font <- TTF.openFont gameFont 32 -- 32: fixed size?
+
+ -- Load the fonts we need
+ let gameFont = "data/lacuna.ttf"
+ font2 <- TTF.openFont gameFont 8 -- 32: fixed size?
+
+ -- Return all resources (just the font)
+ return $ Resources font font2
+
+initializeDisplay :: IO ()
+initializeDisplay =
+ -- Initialise SDL
+ SDL.init [InitEverything]
+
+initGraphs :: Resources -> IO ()
+initGraphs _res = do
+ screen <- SDL.setVideoMode (round width) (round height) 32 [SWSurface]
+ SDL.setCaption gameName ""
+
+ -- Important if we want the keyboard to work right (I don't know
+ -- how to make it work otherwise)
+ SDL.enableUnicode True
+
+ -- Hide mouse
+ SDL.showCursor True
+
+ return ()
+
+render :: Resources -> GameState -> IO()
+render resources shownState = do
+ -- Obtain surface
+ screen <- getVideoSurface
+
+ -- Clear BG
+ fillRect screen Nothing (Pixel backgroundColor)
+
+ -- Paint objects
+ mapM_ (paintObject screen resources (gameTime (gameInfo shownState))) (gameObjects shownState)
+
+ when debugCollisions $
+ mapM_ (paintShape screen resources (gameTime (gameInfo shownState))) (gameObjects shownState)
+
+ -- Paint HUD
+ displayInfo screen resources (gameInfo shownState) (gameObjects shownState)
+
+ -- Paint messages/popups (eg. "Paused", "Level 0", etc.)
+ displayMessage screen resources (gameInfo shownState)
+
+ -- Double buffering
+ SDL.flip screen
+
+-- * Painting functions
+displayInfo :: Surface -> Resources -> GameInfo -> Objects -> IO()
+displayInfo screen resources over objs = do
+ printAlignRight screen resources
+ ("Time: " ++ printf "%.2f" (gameTime over)) (10,50)
+ let p = findPlayer objs
+ case p of
+ Just p' -> let e = playerEnergy p'
+ in printAlignRight screen resources ("Energy: " ++ show e) (10,100)
+ Nothing -> return ()
+
+paintObject :: Surface -> Resources -> Double -> Object -> IO ()
+paintObject screen resources time object =
+ case objectKind object of
+ (Side {}) -> return ()
+ (Ball ballSize) -> do
+ let (px,py) = (\(u,v) -> (u, gameHeight - v)) (objectPos object)
+ let (x,y) = (round *** round) (px,py)
+ (vx,vy) = objectVel object
+ (x',y') = (round *** round) ((px,py) ^+^ (0.1 *^ (vx, -vy)))
+ _ <- SDLP.filledCircle screen x y (round ballSize) (SDL.Pixel ballColor)
+ _ <- SDLP.line screen x y x' y' (SDL.Pixel velColor)
+
+ -- Print position
+ let font = miniFont resources
+ message <- TTF.renderTextSolid font (show $ (round *** round) (objectPos object)) fontColor
+ let w = SDL.surfaceGetWidth message
+ h = SDL.surfaceGetHeight message
+ (x'',y'') = (round *** round) (px,py)
+ rect = SDL.Rect (x''+30) (y''-30) w h
+ SDL.blitSurface message Nothing screen (Just rect)
+ return ()
+
+ (Block sz@(w', h')) -> void $ do
+ let (px,py) = (objectPos object)
+ (x,y) = (round *** round) (px,gameHeight - py -h')
+ (w,h) = (round *** round) sz
+ fillRect screen (Just (Rect x y w h)) (Pixel blockColor)
+
+ (Player state _ vulnerable energy) -> do
+ let blinkOn = vulnerable || (even (round (time * 10)))
+ when blinkOn $ do
+
+ let (px,py) = (\(u,v) -> (u, gameHeight - v - playerHeight)) (objectPos object)
+ let (x,y) = (round *** round) (px,py)
+ (vx,vy) = objectVel object
+ (x',y') = (round *** round) ((px,py) ^+^ (0.1 *^ (vx, -vy)))
+ (w,h) = (round playerWidth, round playerHeight)
+ playerColor = case (state, vulnerable) of
+ (PlayerRight, True) -> playerRightColor
+ (PlayerLeft , True) -> playerLeftColor
+ (PlayerStand, True) -> playerStandColor
+ (PlayerRight, False) -> playerBlinkRightColor
+ (PlayerLeft , False) -> playerBlinkLeftColor
+ (PlayerStand, False) -> playerBlinkStandColor
+
+ fillRect screen (Just (Rect x y w h)) (Pixel playerColor)
+
+ _ <- SDLP.line screen (fromIntegral x) (fromIntegral y) x' y' (SDL.Pixel velColor)
+
+ -- Print position
+ let font = miniFont resources
+ message <- TTF.renderTextSolid font (show $ (round *** round) (objectPos object)) fontColor
+ let w = SDL.surfaceGetWidth message
+ h = SDL.surfaceGetHeight message
+ (x'',y'') = (round *** round) (px,py)
+ rect = SDL.Rect (x''+30) (y''-30) w h
+ SDL.blitSurface message Nothing screen (Just rect)
+ return ()
+
+ Projectile -> do
+ let (x0,y0) = (\(x,y) -> (x - 5, height - y)) $ objectPos object
+ (dx, dy) = (10, snd (objectPos object))
+ (x0', y0', dx', dy') = (round x0, round y0, round dx, round dy)
+ fillRect screen (Just (Rect x0' y0' dx' dy')) (Pixel fireColor)
+ return ()
+
+paintShape :: Surface -> Resources -> Double -> Object -> IO ()
+paintShape screen resources time object =
+ paintShape' screen resources time (objShape object)
+
+paintShape' screen resources time shape =
+ case shape of
+ Rectangle (px, py) (w,h) -> void $ do
+ let x1 = round px
+ x2 = round (px + w)
+ y1 = round (gameHeight - py - h)
+ y2 = round (gameHeight - py)
+ drawThickRectangle screen (Rect x1 y1 x2 y2) (Pixel collisionDebugColor) collisionDebugThickness
+
+ Circle (px, py) rd -> void $ do
+ let x = round px
+ y = round (gameHeight - py)
+ r = round rd
+ drawThickCircle screen x y r (Pixel collisionDebugColor) collisionDebugThickness
+
+ SemiPlane (px, py) s ->
+ let w = round width
+ h = round height
+ in case s of
+ LeftSide -> drawThickLine screen 0 0 0 h (Pixel collisionDebugColor) collisionDebugThickness
+ RightSide -> drawThickLine screen w 0 w h (Pixel collisionDebugColor) collisionDebugThickness
+ TopSide -> drawThickLine screen 0 0 w 0 (Pixel collisionDebugColor) collisionDebugThickness
+ BottomSide -> drawThickLine screen 0 h w h (Pixel collisionDebugColor) collisionDebugThickness
+
+drawThickRectangle surface (Rect x1 y1 x2 y2) pixel 0 = return ()
+drawThickRectangle surface rect@(Rect x1 y1 x2 y2) pixel n = do
+ let n' = n-1
+ SDLP.rectangle surface (Rect (x1-n') (y1-n') (x2+n') (y2+n')) pixel
+ drawThickRectangle surface rect pixel n'
+
+drawThickCircle screen x y r pixel 0 = return ()
+drawThickCircle screen x y r pixel n = do
+ let n' = n-1
+ SDLP.circle screen x y (r+n') pixel
+ drawThickCircle screen x y r pixel n'
+
+drawThickLine screen x1 y1 x2 y2 pixel 0 = return ()
+drawThickLine screen x1 y1 x2 y2 pixel n = do
+ let n' = n-1
+ SDLP.line screen (x1) (y1-n') (x2) (y2-n') pixel
+ SDLP.line screen (x1) (y1+n') (x2) (y2+n') pixel
+ SDLP.line screen (x1-n') (y1) (x2-n') (y2) pixel
+ SDLP.line screen (x1+n') (y1) (x2+n') (y2) pixel
+ drawThickLine screen x1 y1 x2 y2 pixel n'
+
+-- * Painting functions
+displayMessage :: Surface -> Resources -> GameInfo -> IO()
+displayMessage screen resources info = case gameStatus info of
+ GameLoading ->
+ printAlignCenter screen resources ("Level " ++ show (gameLevel info))
+ _ -> return ()
+
+-- * Render text with alignment
+printAlignRight :: Surface -> Resources -> String -> (Int, Int) -> IO ()
+printAlignRight screen resources msg (x,y) = void $ do
+ let font = resFont resources
+ message <- TTF.renderTextSolid font msg fontColor
+ renderAlignRight screen message (x,y)
+
+-- * Render text with alignment
+printAlignCenter :: Surface -> Resources -> String -> IO ()
+printAlignCenter screen resources msg = void $ do
+ let font = resFont resources
+ message <- TTF.renderTextSolid font msg fontColor
+ renderAlignCenter screen message
diff --git a/src/FRP/Yampa/Extra.hs b/src/FRP/Yampa/Extra.hs
new file mode 100644
--- /dev/null
+++ b/src/FRP/Yampa/Extra.hs
@@ -0,0 +1,182 @@
+{-# LANGUAGE MultiWayIf #-}
+module FRP.Yampa.Extra where
+
+import Debug.Trace
+import FRP.Yampa
+import FRP.Yampa.InternalCore
+import FRP.Yampa.Switches
+
+-- * Auxiliary FRP stuff
+maybeToEvent :: Maybe a -> Event a
+maybeToEvent = maybe noEvent Event
+
+-- ** ListSF that never dies or produces offspring
+inertSF :: SF a b -> ListSF a b
+inertSF sf = ListSF (sf >>> arr (\o -> (o, False, [])))
+
+-- ** Event-producing SF combinators
+spikeOn :: SF a Bool -> SF a (Event ())
+spikeOn sf = noEvent --> (sf >>> edge)
+
+ifDiff :: Eq a => a -> SF a (Event a)
+ifDiff x = loopPre x $ arr $ \(x',y') ->
+ if x' == y'
+ then (noEvent, x')
+ else (Event x', x')
+
+-- ** Repetitive switching
+
+repeatSF :: (c -> SF a (b, Event c)) -> c -> SF a b
+repeatSF sf c = switch (sf c) (repeatSF sf)
+
+repeatRevSF :: (c -> SF a (b, Event c)) -> c -> SF a b
+repeatRevSF sf c = revSwitch (sf c) (repeatRevSF sf)
+
+restartOn :: SF a b -> SF a (Event c) -> SF a b
+restartOn sf sfc = switch (sf &&& sfc)
+ (\_ -> restartOn sf sfc)
+
+-- restartRevOn :: SF a b -> SF a (Event c) -> SF a b
+-- restartRevOn sf sfc = switch (sf &&& sfc)
+-- (\_ -> restartOn sf sfc)
+--
+
+revSwitch :: SF a (b, Event c) -> (c -> SF a b) -> SF a b
+revSwitch (SF {sfTF = tf10}) k = SF {sfTF = tf0}
+ where
+ tf0 a0 =
+ case tf10 a0 of
+ (sf1, (b0, NoEvent)) -> (switchAux sf1 k, b0)
+ (sf1, (_, Event c0)) -> switchingPoint sf1 k (sfTF (k c0) a0)
+
+ switchingPoint :: SF' a (b, Event c) -> (c -> SF a b) -> (SF' a b, b) -> (SF' a b, b)
+ switchingPoint sf1 k (sfN', b) = (sf', b)
+ where sf' = SF' tf'
+ tf' dt a = if | dt < 0 -> sfTF' (switchAux sf1 k) dt a
+ -- let (sf1', b') = sfTF' sf1 dt a
+ -- in (switchAux sf1' k, b')
+ | dt > 0 -> switchingPoint' sf1 k dt (sfTF' sfN' dt a)
+ | dt == 0 -> switchingPoint sf1 k (sfN', b)
+
+ switchingPoint' :: SF' a (b, Event c) -> (c -> SF a b) -> DTime -> (SF' a b, b) -> (SF' a b, b)
+ switchingPoint' sf1 k accumDT (sfN', b) = (sf', b)
+ where sf' = SF' tf'
+ tf' dt a = let dt' = dt + accumDT
+ in if | dt < 0 -> if | dt' < 0 -> sfTF' (switchAux sf1 k) dt' a
+ | dt' > 0 -> dt' `seq` switchingPoint' sf1 k dt' (sfTF' sfN' dt a)
+ | dt' == 0 -> switchingPoint' sf1 k accumDT (sfN', b)
+ | dt > 0 -> dt' `seq` switchingPoint' sf1 k dt' (sfTF' sfN' dt a)
+ | dt == 0 -> switchingPoint' sf1 k accumDT (sfN', b)
+
+
+ switchAux :: SF' a (b, Event c) -> (c -> SF a b) -> SF' a b
+ switchAux sf1 k = SF' tf
+ where
+ tf dt a =
+ case (sfTF' sf1) dt a of
+ (sf1', (b, NoEvent)) -> (switchAux sf1' k, b)
+ (_, (_, Event c)) -> switchingPoint sf1 k (sfTF (k c) a)
+
+alwaysForward :: SF a b -> SF a b
+alwaysForward sf = SF $ \a -> let (sf', b) = sfTF sf a
+ in (alwaysForward' sf', b)
+
+alwaysForward' :: SF' a b -> SF' a b
+alwaysForward' sf = SF' $ \dt a -> let (sf', b) = sfTF' sf (max dt (-dt)) a
+ in (alwaysForward' sf', b)
+
+checkpoint :: SF a (b, Event (), Event ()) -> SF a b
+checkpoint sf = SF $ \a -> let (sf', (b, save, reset)) = sfTF sf a
+ in case reset of
+ Event () -> error "loop"
+ NoEvent -> let pt = case save of
+ Event () -> Just (Right sf)
+ NoEvent -> Nothing
+ in (checkpoint' pt sf', b)
+
+checkpoint' :: Maybe (Either (SF' a (b, Event (), Event ())) (SF a (b, Event (), Event ())))
+ -> (SF' a (b, Event (), Event ()))
+ -> SF' a b
+checkpoint' rstPt sf' = SF' $ \dt a -> let (sf'', (b, save, reset)) = sfTF' sf' dt a
+ in case reset of
+ Event () -> case rstPt of
+ Nothing -> let pt = case save of
+ Event () -> Just (Left sf'')
+ NoEvent -> rstPt
+ in pt `seq` (checkpoint' pt sf'', b)
+
+ Just (Left sf''') -> (checkpoint' rstPt sf''', b)
+ Just (Right sf ) -> sfTF (checkpoint sf) a
+ NoEvent -> let pt = case save of
+ Event () -> Just (Left sf'')
+ NoEvent -> rstPt
+ in pt `seq` (checkpoint' pt sf'', b)
+
+forgetPast sf = SF $ \a -> let (sf', b) = sfTF sf a
+ in (forgetPast' 0 sf', b)
+
+forgetPast' time sf' = SF' $ \dt a -> let time' = time + dt
+ in -- trace (show time') $
+ if time' < 0
+ then let (sf'', b) = sfTF' sf' (-time) a
+ in (forgetPast' 0 sf'', b)
+ else let (sf'', b) = sfTF' sf' dt a
+ in (forgetPast' time' sf'', b)
+
+limitHistory :: DTime -> SF a b -> SF a b
+limitHistory time sf = SF $ \a -> let (sf', b) = sfTF sf a
+ in (limitHistory' 0 time sf', b)
+
+limitHistory' :: Time -> DTime -> SF' a b -> SF' a b
+limitHistory' curT maxT sf' = SF' $ \dt a -> let curT' = curT + dt
+ time' = if curT' > maxT then maxT else curT'
+ in -- trace (show (dt, curT, maxT, maxMaxT)) $
+ if time' < 0
+ then let (sf'', b) = sfTF' sf' (-curT) a
+ in (limitHistory' 0 maxT sf'', b)
+ else let (sf'', b) = sfTF' sf' dt a
+ in (limitHistory' time' maxT sf'', b)
+
+clocked :: SF a DTime -> SF a b -> SF a b
+clocked clockSF sf = SF $ \a -> let (sf', b) = sfTF sf a
+ (cSF', _) = sfTF clockSF a
+ in (clocked' cSF' sf', b)
+
+clocked' :: SF' a DTime -> SF' a b -> SF' a b
+clocked' clockSF sf = SF' $ \dt a -> let (cSF', dt') = sfTF' clockSF dt a
+ (sf', b) = sfTF' sf dt' a
+ in (clocked' cSF' sf', b)
+
+deltas = localTime >>> loopPre 0 (arr $ \(lt, ot) -> (lt-ot, lt))
+
+type Endo a = a -> a
+
+timeTransform :: Endo DTime -> SF a b -> SF a b
+timeTransform transform sf = SF tf
+ where tf a = let (sf', b) = (sfTF sf) a
+ sf'' = timeTransformF transform sf'
+ in (sf'', b)
+
+timeTransformF :: Endo DTime -> SF' a b -> SF' a b
+timeTransformF transform sf = SF' tf
+ where tf dt a = let dt' = transform dt
+ (sf', b) = (sfTF' sf) dt' a
+ sf'' = timeTransformF transform sf'
+ in (sf'', b)
+
+timeTransformSF :: SF a (DTime -> DTime) -> SF a b -> SF a b
+timeTransformSF sfTime sf = SF tf
+ where tf a = let (sf', b) = (sfTF sf) a
+ (sfTime',_) = (sfTF sfTime) a
+ sf'' = timeTransformSF' sfTime' sf'
+ in (sf'', b)
+
+
+timeTransformSF' :: SF' a (DTime -> DTime) -> SF' a b -> SF' a b
+timeTransformSF' sfTime sf = SF' tf
+ where tf dt a = let (sfTime', transform) = (sfTF' sfTime) dt a
+ dt' = transform dt
+ (sf', b) = (sfTF' sf) dt' a
+ sf'' = timeTransformSF' sfTime' sf'
+ in (sf'', b)
+
diff --git a/src/Game.hs b/src/Game.hs
new file mode 100644
--- /dev/null
+++ b/src/Game.hs
@@ -0,0 +1,681 @@
+{-# LANGUAGE MultiWayIf #-}
+{-# LANGUAGE Arrows #-}
+-- | This module defines the game as a big Signal Function that transforms a
+-- Signal carrying a Input 'Controller' information into a Signal carrying
+-- 'GameState'.
+--
+-- There is no randomness in the game, the only input is the user's.
+-- 'Controller' is an abstract representation of a basic input device with
+-- position information and a /fire/ button.
+--
+-- The output is defined in 'GameState', and consists of basic information
+-- (points, current level, etc.) and a universe of objects.
+--
+-- Objects are represented as Signal Functions as well ('ObjectSF'). This
+-- allows them to react to user input and change with time. Each object is
+-- responsible for itself, but it cannot affect others: objects can watch
+-- others, depend on others and react to them, but they cannot /send a
+-- message/ or eliminate other objects. However, if you would like to
+-- dynamically introduce new elements in the game (for instance, falling
+-- powerups that the player must collect before they hit the ground) then it
+-- might be a good idea to allow objects not only to /kill themselves/ but
+-- also to spawn new object.
+--
+-- This module contains two sections:
+--
+-- - A collection of gameplay SFs, which control the core game loop, carry
+-- out collision detection, , etc.
+--
+-- - One SF per game object. These define the elements in the game universe,
+-- which can observe other elements, depend on user input, on previous
+-- collisions, etc.
+--
+-- You may want to read the basic definition of 'GameState', 'Controller' and
+-- 'ObjectSF' before you attempt to go through this module.
+--
+module Game (wholeGame) where
+
+-- External imports
+import Prelude hiding (id, (.))
+import Control.Category (id, (.))
+import Data.List
+import Data.Maybe
+import Debug.Trace
+import FRP.Yampa -- as Yampa
+-- import FRP.Yampa.InternalCore
+import FRP.Yampa.Extra
+import FRP.Yampa.Switches
+
+-- General-purpose internal imports
+import Data.Extra.Ord
+import Data.Extra.VectorSpace
+import Physics.Oscillator
+import Physics.TwoDimensions.Collisions as Collisions
+import Physics.TwoDimensions.Dimensions
+import Physics.TwoDimensions.GameCollisions
+import Physics.TwoDimensions.Shapes
+import Physics.TwoDimensions.PhysicalObjects
+
+-- Internal iports
+import Constants
+import GameState
+import Input
+import Objects
+import ObjectSF
+import Objects.Walls
+
+-- * General state transitions
+
+-- | Run the game that the player can lose at until ('switch') the player is
+-- completely dead, and then restart the game.
+wholeGame :: SF Controller GameState
+wholeGame = forgetPast $
+ switch (level 0 >>> (identity &&& playerDead))
+ (\_ -> wholeGame)
+
+-- * Game over
+
+-- | Detect the death of a player by searching for it in the scene (SF).
+playerDead :: SF GameState (Event ())
+playerDead = playerDead' ^>> edge
+
+-- | Detect the death of a player by searching for it in the scene.
+playerDead' :: GameState -> Bool
+playerDead' gs = gamePlaying && dead
+ where
+ -- Dead in the game if not present, or if found dead
+ dead = null (filter isPlayer (gameObjects gs))
+ || not (null (filter playerIsDead (gameObjects gs)))
+
+ -- Player dead if it has no more lives left
+ playerIsDead o = case objectKind o of
+ (Player _ lives _ _) -> lives < 0
+ otherwise -> False
+
+ -- This is only defined when the game is in progress.
+ gamePlaying = GamePlaying == gameStatus (gameInfo gs)
+
+-- | Show loading screen for 2 seconds, then move on to play
+-- the game.
+level :: Int -> SF Controller GameState
+level n = switch
+ (levelLoading n &&& after 2 ()) -- show loading screen for 2 seconds
+ (\_ -> levelLoaded n)
+
+-- | Play a level till completed, then move on to the next level.
+levelLoaded :: Int -> SF Controller GameState
+levelLoaded n = switch
+ (playLevel n >>> (identity &&& outOfEnemies))
+ (\_ -> level (n + 1))
+
+timeProgression :: SF Controller (DTime -> DTime)
+timeProgression = slowDown
+ -- proc (c) -> do
+ -- let rev = if controllerReverse c then ((-1)*) else id
+ -- returnA -< rev
+
+slowDown :: SF Controller (DTime -> DTime)
+slowDown = proc (c) -> do
+ rec let slow = controllerReverse c
+ unit = if | power' >= 0 && slow -> (-1)
+ | power' >= maxPower -> 0
+ | otherwise -> 1
+ power <- (maxPower +) ^<< integral -< unit
+ let power' = min maxPower (max 0 power)
+ dtF = if slow && (power' > 0) then (0.1*) else id
+ returnA -< dtF
+ where
+ maxPower :: Double
+ maxPower = 5
+
+
+timeProgression' :: SF ObjectInput (DTime -> DTime)
+timeProgression' = arr userInput >>> stopClock
+
+stopClock :: SF Controller (DTime -> DTime)
+stopClock = switch (arr controllerHalt >>> arr (\c' -> if c' then (const 0, Event ()) else (id, noEvent)))
+ (\_ -> switch (constant (const 0) &&& after 25 ())
+ (\_ -> stopClock))
+
+-- | Produce a constant game state of loading a particular level.
+levelLoading :: Int -> SF a GameState
+levelLoading n = constant (GameState [] (GameInfo 0 n GameLoading))
+
+-- | Play one level indefinitely (it never ends or restarts).
+playLevel :: Int -> SF Controller GameState
+playLevel n = playLevel' n
+ -- checkpoint $ proc (c) -> do
+ -- take <- edge <<^ controllerCheckPointSave -< c
+ -- restore <- edge <<^ controllerCheckPointRestore -< c
+ -- g <- playLevel' n -< c
+ -- returnA -< (g, take, restore)
+
+playLevel' :: Int -> SF Controller GameState
+playLevel' n = timeTransformSF timeProgression $ limitHistory 5 $ playLevel'' n
+
+playLevel'' :: Int -> SF Controller GameState
+playLevel'' n = gamePlay (initialObjects n) >>^ composeGameState
+ where
+ -- Compose GameState output from 'gamePlay's output
+ composeGameState :: (Objects, Time) -> GameState
+ composeGameState (objs, t) = GameState objs (GameInfo t n GamePlaying)
+
+-- | Detect when there are no more enemies in the scene.
+outOfEnemies :: SF GameState (Event GameState)
+outOfEnemies = arr outOfEnemies'
+ where
+ outOfEnemies' :: GameState -> (Event GameState)
+ outOfEnemies' gs | null balls = Event gs
+ | otherwise = NoEvent
+ where
+ balls = filter isBall (gameObjects gs)
+
+-- ** Game with partial state information
+
+-- | Given an initial list of objects, it runs the game, presenting the output
+-- from those objects at all times, notifying any time the ball hits the floor,
+-- and and of any additional points made.
+--
+-- This works as a game loop with a post-processing step. It uses
+-- a well-defined initial accumulator and a traditional feedback
+-- loop.
+--
+-- The internal accumulator holds the last known collisions (discarded at every
+-- iteration).
+
+playerEnergy'' :: Objects -> Int
+playerEnergy'' objs =
+ let p = findPlayer objs
+ in case p of
+ Just p' -> playerEnergy p'
+ Nothing -> 0
+
+gameTimeSF = proc (_, (_, e)) -> do
+ dt <- deltas -< ()
+ let dt' = if e < 0 && dt < 0 then (-dt) else dt
+ returnA -< dt'
+
+gamePlay :: [ListSF ObjectInput Object] -> SF Controller (Objects, Time)
+gamePlay objs = loopPre ([], 0) $ clocked gameTimeSF (gamePlay' objs)
+ -- Process physical movement and detect new collisions
+ -- -- Adapt Input
+ -- let oi = ObjectInput input cs
+
+ -- -- Step
+ -- -- Each obj processes its movement forward
+ -- ol <- dlSwitch objs -< oi
+ -- let cs' = detectCollisions ol
+
+ -- let energyLeft = playerEnergy'' ol
+
+ -- -- Output
+ -- tLeft <- time -< ()
+ -- returnA -< ((ol, tLeft), (cs', energyLeft))
+
+-- gamePlay' :: SF (Controller, (Collisions, Int)) ((Objects, Time), (Collisions, Int))
+gamePlay' :: [ListSF ObjectInput Object]
+ -> SF (Controller, (Objects.Collisions, Int))
+ (([Object], Time), (Collisions.Collisions String, Int))
+gamePlay' objs =
+ proc (input, (cs, el)) -> do
+ -- Adapt Input
+ let oi = ObjectInput input cs
+
+ -- Step
+ -- Each obj processes its movement forward
+ ol <- dlSwitch objs -< oi
+ let cs' = detectCollisions ol
+
+ let eleft = playerEnergy'' ol
+
+ -- Output
+ tLeft <- time -< ()
+ returnA -< ((ol, tLeft), (cs', eleft))
+
+-- * Game objects
+--
+-- | Objects initially present: the walls, the ball, the player and the blocks.
+initialObjects :: Int -> [ListSF ObjectInput Object]
+initialObjects level =
+ objEnemies level ++ blocks level ++ objPlayers ++ walls
+ where
+ walls = [ inertSF objSideRight
+ , inertSF objSideTop
+ , inertSF objSideLeft
+ , inertSF objSideBottom
+ ]
+
+-- ** Enemies
+
+-- | Defines the enemies depending on the level.
+--
+-- This function is paired with 'blocks', because there could be inconsistent
+-- initial positions in which blocks and enemies already overlap.
+--
+-- WARNING: All objects need different names, both at the beginning and during
+-- gameplay.
+
+objEnemies :: Int -> [ListSF ObjectInput Object]
+
+objEnemies 0 =
+ [ splittingBall ballWidth "ballEnemy1" (600, 300) (360, -350) ]
+
+objEnemies 1 =
+ [ splittingBall ballMedium "ballEnemy1" (width/4, 300) (360, -350)
+ , splittingBall ballMedium "ballEnemy2" (3*width/4, 300) (360, -350) ]
+
+objEnemies 2 =
+ map ballLeft [1..4] ++ map ballRight [1..4]
+ where baseL = 20
+ sep = width / 20
+ baseR = width - (baseL + 4 * sep)
+
+ ballLeft n = splittingBall ballSmall ("ballEnemyL" ++ show n)
+ (baseL + n * sep, 100) (-200, -200)
+
+ ballRight n = splittingBall ballSmall ("ballEnemyR" ++ show n)
+ (baseR + n * sep, 100) (200, -200)
+
+objEnemies n =
+ [ splittingBall ballBig "ballEnemy1" (600, 300) (360, -350) ]
+
+-- ** Blocks
+--
+-- Blocks are horizontal rectangles that /every/ other element collides
+-- with. They need not be static.
+
+-- | List of blocks depending on the level.
+blocks :: Int -> [ListSF ObjectInput Object]
+blocks 0 = [ objBlock "block1" (200, 55) (100, 50) ]
+blocks 1 = [ movingBlock "block1" (400, 200) (100, 50) 200 10 0 0 ]
+blocks 2 = [ movingBlock "block1" (400, 200) (100, 50) 0 0 100 10 ]
+blocks 3 = [ movingBlock "block1" (324, 200) (100, 40) 200 6 0 0
+ , movingBlock "block2" (700, 200) (100, 40) 200 6 100 10
+ ]
+blocks n = [ objBlock "block1" (200, 200) (100, 50) ]
+
+-- *** Moving blocks
+
+-- | A moving block with an initial position and size, and horizontal and
+-- vertical amplitude and periods. If an amplitude is /not/ zero, the
+-- block moves along that dimension using a periodic oscillator
+-- (see the SF 'osci').
+
+movingBlock :: String
+ -> Pos2D -> Size2D -- Geometry
+ -> Double -> Double -- Horizontal oscillation amplitude and period
+ -> Double -> Double -- Vertical oscillation amplitude and period
+ -> ListSF ObjectInput Object
+movingBlock name (px, py) size hAmp hPeriod vAmp vPeriod = ListSF $ proc _ -> do
+ px' <- vx -< px
+ py' <- vy -< py
+ returnA -< (Object { objectName = name
+ , objectKind = Block size
+ , objectPos = (px', py')
+ , objectVel = (0,0)
+ , canCauseCollisions = False
+ , collisionEnergy = 0
+ }, False, [])
+
+ where
+
+ -- To avoid errors, we check that the amplitude is non-zero, otherwise
+ -- just pass the given position along.
+ vx :: SF Double Double
+ vx = if hAmp /= 0 then (px +) ^<< osci hAmp hPeriod else identity
+
+ -- To avoid errors, we check that the amplitude is non-zero, otherwise
+ -- just pass the given position along.
+ vy :: SF Double Double
+ vy = if vAmp /= 0 then (py +) ^<< osci vAmp vPeriod else identity
+
+-- | Generic block builder, given a name, a size and its base
+-- position.
+objBlock :: ObjectName -> Pos2D -> Size2D -> ListSF ObjectInput Object
+objBlock name pos size = ListSF $ timeTransformSF timeProgression' $ constant
+ (Object { objectName = name
+ , objectKind = Block size
+ , objectPos = pos
+ , objectVel = (0,0)
+ , canCauseCollisions = False
+ , collisionEnergy = 0
+ }, False, [])
+
+-- ** Enemy sizes
+ballGiant = ballWidth
+ballBig = ballGiant / 2
+ballMedium = ballBig / 2
+ballSmall = ballMedium / 2
+
+-- ** Player
+objPlayers :: [ListSF ObjectInput Object]
+objPlayers =
+ [ player initialLives playerName (320, 20) True ]
+
+-- ** Guns
+
+gun :: String -> SF (ObjectInput, Pos2D) [ListSF ObjectInput Object]
+gun name = normalGun name
+ -- To switch between different kinds of guns
+ -- gun name = switch
+ -- (normalGun name &&& after 5 ())
+ -- (\_ -> multipleGun name)
+
+-- *** Normal gun, fires one shot at a time
+
+normalGun :: String -> SF (ObjectInput, Pos2D) [ListSF ObjectInput Object]
+normalGun name = revSwitch (constant [] &&& gunFired name)
+ (\fireLSF -> blockedGun name fireLSF)
+
+blockedGun name fsf = revSwitch (([fsf] --> constant []) &&& fireDead fsf)
+ (\_ -> normalGun name)
+
+fireDead fsf = proc (oi, _) -> do
+ (_, b, _) <- listSF fsf -< oi
+ justDied <- edge -< b
+ returnA -< justDied
+
+gunFired :: String -> SF (ObjectInput, Pos2D) (Event (ListSF ObjectInput Object))
+gunFired name = proc (i, ppos) -> do
+ -- Fire!!
+ newF1 <- edge -< controllerClick (userInput i)
+ uniqId <- (\t -> "fire" ++ name ++ show t) ^<< time -< ()
+
+ let newFire = fire uniqId (fst ppos + playerWidth / 2, 0) False
+ returnA -< newF1 `tag` newFire
+
+eventToList :: Event a -> [ a ]
+eventToList NoEvent = []
+eventToList (Event a) = [a]
+
+-- *** Normal gun, fires one shot at a time
+multipleGun :: String -> SF (ObjectInput, Pos2D) [ListSF ObjectInput Object]
+multipleGun name = eventToList ^<< gunFired name
+
+player :: Int -> String -> Pos2D -> Bool -> ListSF ObjectInput Object
+player lives name p0 vul = ListSF $ proc i -> do
+ (ppos, pvel) <- playerProgress name p0 -< i
+
+ let state = playerState (userInput i)
+
+ -- newF1 <- isEvent ^<< edge -< controllerClick (userInput i)
+ -- uniqId <- (\t -> "fire" ++ name ++ show t) ^<< time -< ()
+ -- let newF1Arrows = [ fire uniqId (fst ppos, 0) False
+ -- | newF1 ]
+
+ newF1Arrows <- gun name -< (i, ppos)
+
+ -- Dead?
+ let hitByBall = not $ null
+ $ collisionMask name ("ball" `isPrefixOf`)
+ $ collisions i
+
+ vulnerable <- alwaysForward $
+ switch (constant vul &&& after 2 ())
+ (\_ -> constant True) -< ()
+
+ dead <- isEvent ^<< edge -< hitByBall && vulnerable
+
+ let newPlayer = [ player (lives-1) name p0 False
+ | dead && lives > 0 ]
+
+ dt <- deltas -< ()
+ energy <- loopPre 5 (arr (dup . max 0 . min 5 . sumTime)) -< dt
+ -- max 0 (min 5 (round (fromIntegral (playerEnergy'' ol) + dt)))
+
+ -- Final player
+ returnA -< (Object { objectName = name
+ , objectKind = Player state lives vulnerable (round energy)
+ , objectPos = ppos
+ , objectVel = pvel
+ , canCauseCollisions = True
+ , collisionEnergy = 1
+ }
+ , dead
+ , newF1Arrows ++ newPlayer)
+
+sumTime :: (DTime, DTime) -> DTime
+sumTime (dt, e) = e + dt
+
+playerState :: Controller -> PlayerState
+playerState controller =
+ case (controllerLeft controller, controllerRight controller) of
+ (True, _) -> PlayerLeft
+ (_, True) -> PlayerRight
+ _ -> PlayerStand
+
+playerName :: String
+playerName = "player"
+
+playerProgress :: String -> Pos2D -> SF ObjectInput (Pos2D, Vel2D)
+playerProgress pid p0 = proc i -> do
+ -- Obtain velocity based on state and input, and obtain
+ -- velocity delta to be applied to the position.
+ v <- repeatSF getVelocity PlayerStand -< userInput i
+
+ let collisionsWithBlocks = filter onlyBlocks (collisions i)
+
+ onlyBlocks (Collision cdata) = any (playerCollisionElem . fst) cdata
+
+ playerCollisionElem s = isBlockId s || isWallId s
+ isBlockId = ("block" `isPrefixOf`)
+ isWallId = ("Wall" `isSuffixOf`)
+
+ let ev = changedVelocity pid collisionsWithBlocks
+ vc = fromMaybe v ev
+
+ (px,py) <- (p0 ^+^) ^<< alwaysForward integral -< vc
+
+ -- Calculate actual velocity based on corrected/capped position
+ v' <- derivative -< (px, py)
+
+ returnA -< ((px, py), v')
+
+ where
+
+ capPlayerPos (px, py) = (px', py')
+ where px' = inRange (0, width - playerWidth) px
+ py' = inRange (0, height - playerHeight) py
+
+ getVelocity :: PlayerState -> SF Controller (Vel2D, Event PlayerState)
+ getVelocity pstate = stateVel pstate &&& stateChanged pstate
+
+ stateVel :: PlayerState -> SF a Vel2D
+ stateVel PlayerLeft = constant (-playerSpeed, 0)
+ stateVel PlayerRight = constant (playerSpeed, 0)
+ stateVel PlayerStand = constant (0, 0)
+
+ stateChanged :: PlayerState -> SF Controller (Event PlayerState)
+ stateChanged oldState = arr playerState >>> ifDiff oldState
+
+-- *** Fire/arrows/bullets/projectiles
+
+-- | This produces bullets that die when they hit the top of the screen.
+-- There's sticky bullets and normal bullets. Sticky bullets get stuck for a
+-- while before they die.
+fire :: String -> Pos2D -> Bool -> ListSF ObjectInput Object
+fire name (x0, y0) sticky = ListSF $ proc i -> do
+
+ -- Calculate arrow tip
+ yT <- (y0+) ^<< integral -< fireSpeed
+ let y = min height yT
+
+ -- Delay death if the fire is "sticky"
+ hit <- revSwitch (never &&& fireHitCeiling) (\_ -> stickyDeath sticky) -< y
+
+ hitBall <- arr (fireCollidedWithBall name) -< collisions i
+ hitBlock <- arr (fireCollidedWithBlock name) -< collisions i
+
+ let dead = isEvent hit || hitBall || hitBlock
+
+ let object = Object { objectName = name
+ , objectKind = Projectile
+ , objectPos = (x0, y)
+ , objectVel = (0, 0)
+ , canCauseCollisions = True
+ , collisionEnergy = 0
+ }
+
+ returnA -< (object, dead, [])
+
+ where
+
+ fireHitCeiling = arr (>= height) >>> edge
+ fireCollidedWithBall bid = not . null . collisionMask bid ("ball" `isPrefixOf`)
+ fireCollidedWithBlock bid = not . null . collisionMask bid ("block" `isPrefixOf`)
+
+stickyDeath :: Bool -> SF a (Event ())
+stickyDeath True = after 30 ()
+stickyDeath False = constant (Event ())
+
+-- *** Ball
+
+splittingBall :: Double -> String -> Pos2D -> Vel2D -> ListSF ObjectInput Object
+splittingBall size bid p0 v0 = ListSF $ timeTransformSF timeProgression' $ proc i -> do
+
+ -- Default, just bouncing behaviour
+ bo <- bouncingBall size bid p0 v0 -< i
+
+ -- Hit fire? If so, it should split
+ click <- edge <<^ ballCollidedWithFire bid -< collisions i
+ let shouldSplit = isEvent click
+
+ -- We need two unique IDs so that collisions work
+ t <- localTime -< ()
+ let offspringIDL = bid ++ show t ++ "L"
+ offspringIDR = bid ++ show t ++ "R"
+
+ let enforceYPositive (x,y) = (x, abs y)
+
+ -- Position and velocity of new offspring
+ let bpos = physObjectPos bo
+ bvel = enforceYPositive $ physObjectVel bo
+ ovel = enforceYPositive $ (\(vx,vy) -> (-vx, vy)) bvel
+
+ -- Offspring size, unless this ball is too small to split
+ let tooSmall = size <= (ballWidth / 8)
+ let offspringSize = size / 2
+
+ -- Calculate offspring, if any
+ let offspringL = splittingBall offspringSize offspringIDL bpos bvel
+ offspringR = splittingBall offspringSize offspringIDR bpos ovel
+ offspring = if shouldSplit && not tooSmall
+ then [ offspringL, offspringR ]
+ else []
+
+ -- If it splits, we just remove this one
+ let dead = shouldSplit
+
+ returnA -< (bo, dead, offspring)
+
+ballCollidedWithFire :: ObjectName -> Objects.Collisions -> Bool
+ballCollidedWithFire bid = not . null . collisionMask bid ("fire" `isPrefixOf`)
+
+-- A bouncing ball moves freely until there is a collision, then bounces and
+-- goes on and on.
+--
+-- This SF needs an initial position and velocity. Every time
+-- there is a bounce, it takes a snapshot of the point of
+-- collision and corrected velocity, and starts again.
+--
+bouncingBall :: Double -> String -> Pos2D -> Vel2D -> ObjectSF
+bouncingBall size bid p0 v0 = repeatRevSF (progressAndBounce size bid) (p0, v0)
+
+
+-- | Calculate the future tentative position, and bounce if necessary. Pass on
+-- snapshot of ball position and velocity if bouncing.
+progressAndBounce :: Double -> String -> (Pos2D, Vel2D)
+ -> SF ObjectInput (Object, Event (Pos2D, Vel2D))
+progressAndBounce size bid (p0, v0) = proc i -> do
+
+ -- Position of the ball, starting from p0 with velicity v0, since the
+ -- time of last switching (or being fired, whatever happened last)
+ -- provided that no obstacles are encountered.
+ o <- freeBall size bid p0 v0 -< i
+
+ -- The ballBounce needs the ball SF' input (which has knowledge of
+ -- collisions), so we carry it parallely to the tentative new
+ -- positions, and then use it to detect when it's time to bounce
+ b <- ballBounce bid -< (i, o)
+
+ returnA -< (o, b)
+
+-- | Detect if the ball must bounce and, if so, take a snapshot of the object's
+-- current position and velocity.
+--
+-- NOTE: To avoid infinite loops when switching, the initial input is discarded
+-- and never causes a bounce. Careful: this prevents the ball from bouncing
+-- immediately after creation, which may or may not be what we want.
+ballBounce :: String -> SF (ObjectInput, Object) (Event (Pos2D, Vel2D))
+ballBounce bid = noEvent --> ballBounce' bid
+
+-- | Detect if the ball must bounce and, if so, take a snapshot of the object's
+-- current position and velocity.
+--
+-- This does the core of the work, and does not ignore the initial input.
+--
+-- It proceeds by detecting whether any collision affects the ball's velocity,
+-- and outputs a snapshot of the object position and the corrected velocity if
+-- necessary.
+ballBounce' :: String -> SF (ObjectInput, Object) (Event (Pos2D, Vel2D))
+ballBounce' bid = proc (ObjectInput ci cs, o) -> do
+ -- HN 2014-09-07: With the present strategy, need to be able to
+ -- detect an event directly after
+ -- ev <- edgeJust -< changedVelocity "ball" cs
+ let collisionsWithoutBalls = filter (not . allBalls) cs
+ allBalls (Collision cdata) = all (isPrefixOf "ball" . fst) cdata
+
+ let collisionsWithoutPlayer = filter (not . anyPlayer)
+ collisionsWithoutBalls
+ anyPlayer (Collision cdata) = any (isPrefixOf "player" . fst) cdata
+
+ let ev = maybeToEvent (changedVelocity bid collisionsWithoutPlayer)
+ returnA -< fmap (\v -> (objectPos o, v)) ev
+
+-- | Position of the ball, starting from p0 with velicity v0, since the time of
+-- last switching (that is, collision, or the beginning of time --being fired
+-- from the paddle-- if never switched before), provided that no obstacles are
+-- encountered.
+freeBall :: Double -> String -> Pos2D -> Vel2D -> ObjectSF
+freeBall size name p0 v0 = proc (ObjectInput ci cs) -> do
+
+ -- Integrate acceleration, add initial velocity and cap speed. Resets both
+ -- the initial velocity and the current velocity to (0,0) when the user
+ -- presses the Halt key (hence the dependency on the controller input ci).
+ vInit <- startAs v0 -< ci
+ vel <- vdiffSF -< (vInit, (0, -1000.8), ci)
+
+ -- Any free moving object behaves like this (but with
+ -- acceleration. This should be in some FRP.NewtonianPhysics
+ -- module)
+ pos <- (p0 ^+^) ^<< integral -< vel
+
+ let obj = Object { objectName = name
+ , objectKind = Ball size
+ , objectPos = pos
+ , objectVel = vel
+ , canCauseCollisions = True
+ , collisionEnergy = 1
+ }
+
+ returnA -< obj
+ where -- Spike every time the user presses the Halt key
+ restartCond = spikeOn (arr controllerStop)
+
+ -- Calculate the velocity, restarting when the user
+ -- requests it.
+ vdiffSF = proc (iv, acc, ci) -> do
+ -- Calculate velocity difference by integrating acceleration
+ -- Reset calculation when user requests to stop balls
+ vd <- restartOn (arr fst >>> integral)
+ (arr snd >>> restartCond) -< (acc, ci)
+
+ -- Add initial velocity, and cap the result
+ v <- arr (uncurry (^+^)) -< (iv, vd)
+ let vFinal = limitNorm v (maxVNorm size)
+
+ returnA -< vFinal
+
+ -- Initial velocity, reset when the user requests it.
+ startAs v0 = revSwitch (constant v0 &&& restartCond)
+ (\_ -> startAs (0,0))
diff --git a/src/GameState.hs b/src/GameState.hs
new file mode 100644
--- /dev/null
+++ b/src/GameState.hs
@@ -0,0 +1,42 @@
+-- | The state of the game during execution. It has two
+-- parts: general info (level, points, etc.) and
+-- the actual gameplay info (objects).
+--
+-- Because the game is always in some running state
+-- (there are no menus, etc.) we assume that there's
+-- always some gameplay info, even though it can be
+-- empty.
+module GameState where
+
+-- import FRP.Yampa as Yampa
+
+import Objects
+import FRP.Yampa (Time)
+
+-- | The running state is given by a bunch of 'Objects' and the current general
+-- 'GameInfo'. The latter contains info regarding the current level, the number
+-- of points, etc.
+--
+-- Different parts of the game deal with these data structures. It is
+-- therefore convenient to group them in subtrees, even if there's no
+-- substantial difference betweem them.
+data GameState = GameState
+ { gameObjects :: !Objects
+ , gameInfo :: !GameInfo
+ }
+
+-- | Initial (default) game state.
+neutralGameState :: GameState
+neutralGameState = GameState
+ { gameObjects = []
+ , gameInfo = GameInfo 0 0 GameLoading
+ }
+
+data GameInfo = GameInfo { gameTime :: Time
+ , gameLevel :: Int
+ , gameStatus :: GameStatus
+ }
+
+data GameStatus = GamePlaying
+ | GameLoading
+ deriving (Eq, Show)
diff --git a/src/Graphics/UI/Extra/SDL.hs b/src/Graphics/UI/Extra/SDL.hs
new file mode 100644
--- /dev/null
+++ b/src/Graphics/UI/Extra/SDL.hs
@@ -0,0 +1,65 @@
+module Graphics.UI.Extra.SDL where
+
+import Control.Monad
+import Data.IORef
+import Graphics.UI.SDL
+
+-- * Types
+
+-- Auxiliary SDL stuff
+isEmptyEvent :: Event -> Bool
+isEmptyEvent NoEvent = True
+isEmptyEvent _ = False
+
+-- * SDL-based clock
+
+initializeTimeRef :: IO (IORef Int)
+initializeTimeRef = do
+ -- Weird shit I have to do to get accurate time!
+ timeRef <- newIORef (0 :: Int)
+ _ <- senseTimeRef timeRef
+ _ <- senseTimeRef timeRef
+ _ <- senseTimeRef timeRef
+ _ <- senseTimeRef timeRef
+
+ return timeRef
+
+senseTimeRef :: IORef Int -> IO Int
+senseTimeRef timeRef = do
+ -- Get time passed since SDL init
+ newTime <- fmap fromIntegral getTicks
+
+ -- Obtain time difference
+ dt <- updateTime timeRef newTime
+ return dt
+
+-- | Updates the time in an IO Ref and returns the time difference
+updateTime :: IORef Int -> Int -> IO Int
+updateTime timeRef newTime = do
+ previousTime <- readIORef timeRef
+ writeIORef timeRef newTime
+ return (newTime - previousTime)
+
+milisecsToSecs :: Int -> Double
+milisecsToSecs m = fromIntegral m / 1000
+
+-- * Rendering
+
+renderAlignRight :: Surface -> Surface -> (Int, Int) -> IO ()
+renderAlignRight screen surface (x,y) = void $ do
+ let rightMargin = surfaceGetWidth screen
+ w = surfaceGetWidth surface
+ h = surfaceGetHeight surface
+ rect = Rect (rightMargin - x - w) y w h
+ blitSurface surface Nothing screen (Just rect)
+
+renderAlignCenter :: Surface -> Surface -> IO ()
+renderAlignCenter screen surface = void $ do
+ let tWidth = surfaceGetWidth screen
+ tHeight = surfaceGetWidth screen
+ w = surfaceGetWidth surface
+ h = surfaceGetHeight surface
+ px = (tWidth - w) `div` 2
+ py = (tHeight - h) `div` 2
+ rect = Rect px py w h
+ blitSurface surface Nothing screen (Just rect)
diff --git a/src/Input.hs b/src/Input.hs
new file mode 100644
--- /dev/null
+++ b/src/Input.hs
@@ -0,0 +1,133 @@
+-- | Defines an abstraction for the game controller and the functions to read
+-- it.
+--
+-- Lower-level devices replicate the higher-level API, and should accomodate to
+-- it. Each device should:
+--
+-- - Upon initialisation, return any necessary information to poll it again.
+--
+-- - Update the controller with its own values upon sensing.
+--
+-- In this case, we only have one: mouse/keyboard combination.
+--
+module Input where
+
+-- External imports
+import Data.IORef
+import Graphics.UI.SDL as SDL
+
+-- Internal imports
+import Control.Extra.Monad
+import Data.Extra.IORef
+import Graphics.UI.Extra.SDL
+
+-- * Game controller
+
+-- | Controller info at any given point.
+data Controller = Controller
+ { controllerPos :: (Double, Double)
+ , controllerLeft :: Bool
+ , controllerRight :: Bool
+ , controllerClick :: Bool
+ , controllerStop :: Bool
+ , controllerPause :: Bool
+ , controllerExit :: Bool
+ , controllerFast :: Bool
+ , controllerSlow :: Bool
+ , controllerSuperSlow :: Bool
+ , controllerReverse :: Bool
+ , controllerHalt :: Bool
+ , controllerFullscreen :: Bool
+ , controllerCheckPointSave :: Bool
+ , controllerCheckPointRestore :: Bool
+ }
+
+-- | Controller info at any given point, plus a pointer
+-- to poll the main device again. This is safe,
+-- since there is only one writer at a time (the device itself).
+newtype ControllerRef =
+ ControllerRef { controllerData :: (IORef Controller, Controller -> IO Controller) }
+
+-- * General API
+
+-- | Initialize the available input devices. This operation
+-- returns a reference to a controller, which enables
+-- getting its state as many times as necessary. It does
+-- not provide any information about its nature, abilities, etc.
+initializeInputDevices :: IO ControllerRef
+initializeInputDevices = do
+ nr <- newIORef defaultInfo
+ return $ ControllerRef (nr, sdlGetController)
+ where defaultInfo = Controller (0,0) False False -- Position and direction
+ False -- Fire
+ False -- Stop balls
+ False -- Pause
+ False -- Exit
+ False False False -- Speed control
+ False -- Reverse time
+ False -- Halt
+ False -- Fullscreen
+ False -- CheckpointSave
+ False -- CheckpointRestore
+
+-- | Sense from the controller, providing its current
+-- state. This should return a new Controller state
+-- if available, or the last one there was.
+--
+-- It is assumed that the sensing function is always
+-- callable, and that it knows how to update the
+-- Controller info if necessary.
+senseInput :: ControllerRef -> IO Controller
+senseInput (ControllerRef (cref, sensor)) =
+ modifyIORefIO cref sensor
+
+type ControllerDev = IO (Maybe (Controller -> IO Controller))
+
+-- * SDL API (mid-level)
+
+-- ** Sensing
+
+-- | Sense the SDL keyboard and mouse and update
+-- the controller. It only senses the mouse position,
+-- the primary mouse button, and the p key to pause
+-- the game.
+--
+-- We need a non-blocking controller-polling function.
+-- TODO: Check http://gameprogrammer.com/fastevents/fastevents1.html
+sdlGetController :: Controller -> IO Controller
+sdlGetController info =
+ foldLoopM info pollEvent (not.isEmptyEvent) ((return .) . handleEvent)
+
+handleEvent :: Controller -> SDL.Event -> Controller
+handleEvent c e =
+ case e of
+ MouseMotion x y _ _ -> c { controllerPos = (fromIntegral x, fromIntegral y)}
+ MouseButtonDown _ _ ButtonLeft -> c { controllerClick = True }
+ MouseButtonUp _ _ ButtonLeft -> c { controllerClick = False }
+ KeyDown (Keysym { symKey = SDLK_LEFT }) -> c { controllerLeft = True }
+ KeyUp (Keysym { symKey = SDLK_LEFT }) -> c { controllerLeft = False }
+ KeyDown (Keysym { symKey = SDLK_RIGHT }) -> c { controllerRight = True }
+ KeyUp (Keysym { symKey = SDLK_RIGHT }) -> c { controllerRight = False }
+ KeyUp (Keysym { symKey = SDLK_p }) -> c { controllerPause = not (controllerPause c) }
+ KeyUp (Keysym { symKey = SDLK_f }) -> c { controllerFullscreen = not (controllerFullscreen c) }
+ KeyDown (Keysym { symKey = SDLK_w }) -> c { controllerSuperSlow = True }
+ KeyUp (Keysym { symKey = SDLK_w }) -> c { controllerSuperSlow = False }
+ KeyDown (Keysym { symKey = SDLK_s }) -> c { controllerSlow = True }
+ KeyUp (Keysym { symKey = SDLK_s }) -> c { controllerSlow = False }
+ KeyDown (Keysym { symKey = SDLK_x }) -> c { controllerFast = True }
+ KeyUp (Keysym { symKey = SDLK_x }) -> c { controllerFast = False }
+ KeyDown (Keysym { symKey = SDLK_r }) -> c { controllerReverse = True }
+ KeyUp (Keysym { symKey = SDLK_r }) -> c { controllerReverse = False }
+ KeyDown (Keysym { symKey = SDLK_t }) -> c { controllerHalt = True }
+ KeyUp (Keysym { symKey = SDLK_t }) -> c { controllerHalt = False }
+ KeyDown (Keysym { symKey = SDLK_h }) -> c { controllerStop = True }
+ KeyUp (Keysym { symKey = SDLK_h }) -> c { controllerStop = False }
+ KeyDown (Keysym { symKey = SDLK_c }) -> c { controllerCheckPointSave = True }
+ KeyUp (Keysym { symKey = SDLK_c }) -> c { controllerCheckPointSave = False }
+ KeyDown (Keysym { symKey = SDLK_v }) -> c { controllerCheckPointRestore = True }
+ KeyUp (Keysym { symKey = SDLK_v }) -> c { controllerCheckPointRestore = False }
+ KeyDown (Keysym { symKey = SDLK_SPACE }) -> c { controllerClick = True }
+ KeyUp (Keysym { symKey = SDLK_SPACE }) -> c { controllerClick = False }
+ KeyDown (Keysym { symKey = SDLK_ESCAPE}) -> c { controllerExit = True }
+ _ -> c
+
diff --git a/src/Main.hs b/src/Main.hs
new file mode 100644
--- /dev/null
+++ b/src/Main.hs
@@ -0,0 +1,42 @@
+import Control.Applicative
+import Data.IORef
+import FRP.Yampa as Yampa
+import System.Mem
+
+import Game
+import Display
+import Input
+import Graphics.UI.Extra.SDL
+
+main :: IO ()
+main = do
+
+ initializeDisplay
+
+ timeRef <- initializeTimeRef
+ controllerRef <- initializeInputDevices
+ res <- loadResources
+
+ initGraphs res
+ reactimate (senseInput controllerRef)
+ (\_ -> do
+ -- Get clock and new input
+ mInput <- senseInput controllerRef
+ dtSecs <- senseTime timeRef mInput
+ -- trace ("Time : " ++ printf "%.5f" dtSecs) $
+ return (if controllerPause mInput then 0 else dtSecs, Just mInput)
+ )
+ (\_ (e,c) -> do render res e
+ performGC
+ return (controllerExit c)
+ )
+ (wholeGame &&& arr id)
+
+senseTime :: IORef Int -> Controller -> IO DTime
+senseTime timeRef = \mInput ->
+ let tt = if controllerSlow mInput then (/10) else id
+ tt1 = if controllerSuperSlow mInput then (/100) else tt
+ tt2 = if controllerFast mInput then (*10) else tt1
+ tt3 = id -- if controllerReverse mInput then (\x -> -x) else id
+ in (tt3 . tt2 . milisecsToSecs) <$> senseTimeRef timeRef
+
diff --git a/src/ObjectSF.hs b/src/ObjectSF.hs
new file mode 100644
--- /dev/null
+++ b/src/ObjectSF.hs
@@ -0,0 +1,44 @@
+-- | Objects as signal functions.
+--
+-- Live objects in the game take user input and the game universe
+-- and define their state in terms of that. They can remember what
+-- happened (see Yampa's Arrow combinators, which hide continuations),
+-- change their behaviour (see switches in Yampa).
+module ObjectSF where
+
+import FRP.Yampa
+
+import Objects
+import Input
+
+-- | Objects are defined as transformations that take 'ObjectInput' signals and
+-- return 'ObjectOutput' signals.
+type ObjectSF = SF ObjectInput Object
+
+-- | In order to determine its new output, an object needs to know the user's
+-- desires ('userInput'), whether there have been any collisions
+-- ('collisions').
+--
+-- The reason for depending on 'Collisions' is that objects may ``change''
+-- when hit (start moving in a different direction).
+data ObjectInput = ObjectInput
+ { userInput :: Controller
+ , collisions :: Collisions
+ }
+
+-- -- | What we can see about each live object at each time. It's a
+-- -- snapshot of the object.
+-- data ObjectOutput = ObjectOutput
+-- { outputObject :: Object -- ^ The object's state (position, shape, etc.).
+-- }
+
+-- -- | List of identifiable objects. Used to work with dynamic object
+-- -- collections.
+-- type ObjectSFs = IL ObjectSF
+
+-- extractObjects :: Functor f => SF (f ObjectOutput) (f Object)
+-- extractObjects = arr (fmap outputObject)
+--
+-- -- | A list of object outputs
+-- type ObjectOutputs = [ObjectOutput]
+--
diff --git a/src/Objects.hs b/src/Objects.hs
new file mode 100644
--- /dev/null
+++ b/src/Objects.hs
@@ -0,0 +1,93 @@
+{-# LANGUAGE TypeSynonymInstances #-}
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+-- | Game objects and collisions.
+module Objects where
+
+import Control.Arrow ((***))
+import Data.Maybe (listToMaybe)
+import FRP.Yampa.VectorSpace
+
+import qualified Physics.TwoDimensions.Collisions as C
+import Physics.TwoDimensions.Dimensions
+import Physics.TwoDimensions.PhysicalObjects
+import Physics.TwoDimensions.Shapes
+
+import Constants
+
+type Collision = C.Collision ObjectName
+type Collisions = C.Collisions ObjectName
+
+-- * Objects
+
+type Objects = [Object]
+type ObjectName = String
+
+-- | Objects have logical properties (ID, kind, dead, hit), shape properties
+-- (kind), physical properties (kind, pos, vel, acc) and collision properties
+-- (hit, 'canCauseCollisions', energy, displaced).
+data Object = Object { objectName :: !ObjectName
+ , objectKind :: !ObjectKind
+ , objectPos :: !Pos2D
+ , objectVel :: !Vel2D
+ , canCauseCollisions :: !Bool
+ , collisionEnergy :: !Double
+ }
+ deriving (Show)
+
+findPlayer = listToMaybe . filter isPlayer
+
+isBall :: Object -> Bool
+isBall o = case objectKind o of
+ Ball _ -> True
+ _ -> False
+
+isPlayer :: Object -> Bool
+isPlayer o = case objectKind o of
+ Player {} -> True
+ _ -> False
+
+-- | The kind of object and any size properties.
+data ObjectKind = Ball !Double -- radius
+ | Player !PlayerState !Int {- lives -} !Bool {- Vulnerable -} !Int {- energy -}
+ | Side !Side
+ | Projectile
+ | Block !Size2D
+ -- | PowerUp PowerUp
+ deriving (Show,Eq)
+
+data PlayerState = PlayerRight
+ | PlayerLeft
+ | PlayerStand
+ deriving (Eq, Show)
+
+playerEnergy :: Object -> Int
+playerEnergy o = case objectKind o of
+ p@(Player _ _ _ e) -> e
+ _ -> 0
+
+-- Partial function!
+objectSize :: Object -> Size2D
+objectSize object = case objectKind object of
+ (Ball r) -> let w = 2*r in (w, w)
+ (Player {}) -> (playerWidth, playerHeight)
+ (Block s) -> s
+
+instance PhysicalObject Object String Shape where
+ physObjectPos = objectPos
+ physObjectVel = objectVel
+ physObjectElas = collisionEnergy
+ physObjectShape = objShape
+ physObjectCollides = canCauseCollisions
+ physObjectId = objectName
+ physObjectUpdatePos = \o p -> o { objectPos = p }
+ physObjectUpdateVel = \o v -> o { objectVel = v }
+
+objShape :: Object -> Shape
+objShape obj = case objectKind obj of
+ Ball r -> Circle p r
+ Side s -> SemiPlane p s
+ Player {} -> Rectangle p (playerWidth, playerHeight)
+ Projectile -> Rectangle (px - 5, 0) (10, py)
+ Block s@(w,h) -> Rectangle (px, py) s
+ where p@(px,py) = objectPos obj
diff --git a/src/Objects/Walls.hs b/src/Objects/Walls.hs
new file mode 100644
--- /dev/null
+++ b/src/Objects/Walls.hs
@@ -0,0 +1,101 @@
+{-# LANGUAGE Arrows #-}
+-- | This module defines the game as a big Signal Function that transforms a
+-- Signal carrying a Input 'Controller' information into a Signal carrying
+-- 'GameState'.
+--
+-- There is no randomness in the game, the only input is the user's.
+-- 'Controller' is an abstract representation of a basic input device with
+-- position information and a /fire/ button.
+--
+-- The output is defined in 'GameState', and consists of basic information
+-- (points, current level, etc.) and a universe of objects.
+--
+-- Objects are represented as Signal Functions as well ('ObjectSF'). This
+-- allows them to react to user input and change with time. Each object is
+-- responsible for itself, but it cannot affect others: objects can watch
+-- others, depend on others and react to them, but they cannot /send a
+-- message/ or eliminate other objects. However, if you would like to
+-- dynamically introduce new elements in the game (for instance, falling
+-- powerups that the player must collect before they hit the ground) then it
+-- might be a good idea to allow objects not only to /kill themselves/ but
+-- also to spawn new object.
+--
+-- This module contains two sections:
+--
+-- - A collection of gameplay SFs, which control the core game loop, carry
+-- out collision detection, , etc.
+--
+-- - One SF per game object. These define the elements in the game universe,
+-- which can observe other elements, depend on user input, on previous
+-- collisions, etc.
+--
+-- You may want to read the basic definition of 'GameState', 'Controller' and
+-- 'ObjectSF' before you attempt to go through this module.
+--
+module Objects.Walls where
+
+-- External imports
+import Prelude hiding (id, (.))
+import Control.Category (id, (.))
+import Data.List
+import Data.Maybe
+import Debug.Trace
+import FRP.Yampa
+import FRP.Yampa.Extra
+import FRP.Yampa.Switches
+
+-- General-purpose internal imports
+import Data.Extra.Ord
+import Data.Extra.VectorSpace
+import Physics.Oscillator
+import Physics.TwoDimensions.Collisions as Collisions
+import Physics.TwoDimensions.Dimensions
+import Physics.TwoDimensions.GameCollisions
+import Physics.TwoDimensions.Shapes
+import Physics.TwoDimensions.PhysicalObjects
+
+-- Internal iports
+import Constants
+import GameState
+import Input
+import Objects
+import ObjectSF
+
+-- * Walls
+
+-- | Walls. Each wall has a side and a position.
+--
+-- NOTE: They are considered game objects instead of having special treatment.
+-- The function that turns walls into 'Shape's for collision detection
+-- determines how big they really are. In particular, this has implications in
+-- ball-through-paper effects (ball going through objects, potentially never
+-- coming back), which can be seen if the FPS suddently drops due to CPU load
+-- (for instance, if a really major Garbage Collection kicks in. One potential
+-- optimisation is to trigger these with every SF iteration or every rendering,
+-- to decrease the workload and thus the likelyhood of BTP effects.
+objSideRight :: ObjectSF
+objSideRight = objWall "rightWall" RightSide (gameWidth, 0)
+
+-- | See 'objSideRight'.
+objSideLeft :: ObjectSF
+objSideLeft = objWall "leftWall" LeftSide (0, 0)
+
+-- | See 'objSideRight'.
+objSideTop :: ObjectSF
+objSideTop = objWall "topWall" TopSide (0, 0)
+
+-- | See 'objSideRight'.
+objSideBottom :: ObjectSF
+objSideBottom = objWall "bottomWall" BottomSide (0, gameHeight)
+
+-- | Generic wall builder, given a name, a side and its base
+-- position.
+objWall :: ObjectName -> Side -> Pos2D -> ObjectSF
+objWall name side pos = arr $ \(ObjectInput ci cs) ->
+ Object { objectName = name
+ , objectKind = Side side
+ , objectPos = pos
+ , objectVel = (0,0)
+ , canCauseCollisions = False
+ , collisionEnergy = 0
+ }
diff --git a/src/Physics/TwoDimensions/Collisions.hs b/src/Physics/TwoDimensions/Collisions.hs
new file mode 100644
--- /dev/null
+++ b/src/Physics/TwoDimensions/Collisions.hs
@@ -0,0 +1,188 @@
+{-# LANGUAGE FlexibleContexts #-}
+-- | A trivial collision subsystem.
+--
+-- Based on the physics module, it determines the side of collision
+-- between shapes.
+module Physics.TwoDimensions.Collisions where
+
+import Data.Extra.Num
+import Data.Maybe
+import FRP.Yampa.VectorSpace
+import Physics.TwoDimensions.Dimensions
+import Physics.TwoDimensions.PhysicalObjects
+import Physics.TwoDimensions.Shapes
+
+import Collisions
+
+-- * Collision points
+data CollisionPoint = CollisionSide Side
+ | CollisionAngle Double
+
+-- | Calculates the collision side of a shape
+-- that collides against another.
+--
+-- PRE: the shapes do collide. Use 'overlapShape' to check.
+shapeCollisionPoint :: Shape -> Shape -> CollisionPoint
+shapeCollisionPoint (Circle p1 _) (Circle p2 _) = CollisionAngle angle
+ where (px,py) = p2 ^-^ p1
+ angle = atan2 py px
+shapeCollisionPoint (Circle _ _) (SemiPlane _ s2) = CollisionSide s2
+shapeCollisionPoint (Circle p1 s1) (Rectangle p2 s2) =
+ velCollitionSide $ fromJust $ responseCircleAABB (p1, s1) (rectangleToCentre (p2, s2))
+
+shapeCollisionPoint (SemiPlane _ s1) (Circle _ _ ) = CollisionSide (oppositeSide s1)
+shapeCollisionPoint (SemiPlane _ _) (SemiPlane _ s2) = CollisionSide s2
+shapeCollisionPoint p@(SemiPlane _ _) r@(Rectangle _ _) = let CollisionSide side = shapeCollisionPoint r p
+ in CollisionSide (oppositeSide side)
+
+shapeCollisionPoint r@(Rectangle _ _) c@(Circle _ _) = let CollisionSide side = shapeCollisionPoint c r
+ in CollisionSide (oppositeSide side)
+shapeCollisionPoint r@(Rectangle _ _) (SemiPlane p2 s2) = let (p2', s2') = semiplaneRectangle p2 s2
+ in shapeCollisionPoint r (Rectangle p2' s2')
+shapeCollisionPoint (Rectangle p1 s1) (Rectangle p2 s2) =
+ velCollitionSide $ fromJust $ responseAABB2 (p1, s1) (p2, s2)
+
+velCollitionSide (vx, vy)
+ | vx < 0 && abs vx > abs vy = CollisionSide RightSide
+ | vx > 0 && abs vx > abs vy = CollisionSide LeftSide
+ | vy > 0 && abs vx < abs vy = CollisionSide TopSide
+ -- | vy > 0 && abs vx < abs vy
+ | otherwise = CollisionSide BottomSide
+
+-- * Collisions
+type Collisions k = [Collision k]
+
+-- | A collision is a list of objects that collided, plus their velocities as
+-- modified by the collision.
+--
+-- Take into account that the same object could take part in several
+-- simultaneous collitions, so these velocities should be added (per object).
+data Collision k = Collision
+ { collisionData :: [(k, Vel2D)] } -- ObjectId x Velocity
+ deriving Show
+
+detectCollision :: (PhysicalObject o k Shape) => o -> o -> Maybe (Collision k)
+detectCollision obj1 obj2
+ | overlap obj1 obj2
+ = case (physObjectShape obj1, physObjectShape obj2) of
+ (Circle _ _, Circle _ _) ->
+ if vrn < 0
+ then Just response
+ else Nothing
+ _ -> Just response
+ | otherwise = Nothing
+
+ where response = collisionResponseObj obj1 obj2
+ relativeP = physObjectPos obj1 ^-^ physObjectPos obj2
+ relativeV = physObjectVel obj1 ^-^ physObjectVel obj2
+ -- If the inner product between the relative position and velocity
+ -- is negative, then the two objects are approaching each other.
+ -- Note that there is no collision if vrn = 0. This could be
+ -- because the objects are at the same position and thus cannot get
+ -- any closer. Or because their relative velocity is 0 and thus are
+ -- not approaching for that reason. This, if there *is* a collision,
+ -- then we know that both the relative position and velocity is non 0,
+ -- and it is safe to e.g. normalize the relative position as is done
+ -- in "correctVel" below.
+ vrn = relativeV `dot` relativeP
+
+ -- HN 2016-04-26: Old code: Problematic if same positions! But all we
+ -- want to know here is if the objects are approaching each other.
+ -- For this, all that matters is the sign of the inner product. There
+ -- is no need to normalize the relative position!
+ --
+ -- colNormal = normalize (physObjectPos obj1 ^-^ physObjectPos obj2)
+ -- relativeV = physObjectVel obj1 ^-^ physObjectVel obj2
+ -- vrn = relativeV `dot` colNormal
+
+overlap :: PhysicalObject o k Shape => o -> o -> Bool
+overlap obj1 obj2 =
+ overlapShape (physObjectShape obj1) (physObjectShape obj2)
+
+collisionPoint :: PhysicalObject o k Shape => o -> o -> CollisionPoint
+collisionPoint obj1 obj2 =
+ shapeCollisionPoint (physObjectShape obj1) (physObjectShape obj2)
+
+collisionResponseObj :: PhysicalObject o k Shape => o -> o -> Collision k
+collisionResponseObj o1 o2 = Collision $
+ map objectToCollision [(o1, collisionPt, o2), (o2, collisionPt', o1)]
+ where
+ collisionPt = collisionPoint o1 o2
+ collisionPt' = collisionPoint o2 o1
+
+ objectToCollision (o,pt,o') =
+ ( physObjectId o
+ , correctVel (physObjectPos o) (physObjectPos o')
+ (physObjectVel o) (physObjectVel o')
+ pt (physObjectElas o)
+ )
+
+correctVel :: Pos2D -> Pos2D -> Vel2D -> Vel2D -> CollisionPoint -> Double -> Vel2D
+-- Specialised cases: just more optimal execution
+correctVel _p1 _p2 v1 _ _ 0 = v1
+-- Collision against a wall
+correctVel _p1 _p2 (v1x,v1y) _ (CollisionSide TopSide) e = (e * v1x, e * ensurePos v1y)
+correctVel _p1 _p2 (v1x,v1y) _ (CollisionSide BottomSide) e = (e * v1x, e * ensureNeg v1y)
+correctVel _p1 _p2 (v1x,v1y) _ (CollisionSide LeftSide) e = (e * ensurePos v1x, e * v1y)
+correctVel _p1 _p2 (v1x,v1y) _ (CollisionSide RightSide) e = (e * ensureNeg v1x, e * v1y)
+-- General case
+correctVel p1 p2 (v1x,v1y) (v2x, v2y) (CollisionAngle _) e = (v1x, v1y) ^+^ ((e * j) *^ colNormal)
+ where colNormal = normalize (p1 ^-^ p2)
+ relativeV = (v1x,v1y) ^-^ (v2x,v2y)
+ vrn = relativeV `dot` colNormal
+ j = (-1) *^ vrn / (colNormal `dot` colNormal)
+
+-- | Return the new velocity as changed by the collection of collisions.
+--
+-- HN 2014-09-07: New interface to collision detection.
+--
+-- The assumption is that collision detection happens globally and that the
+-- changed velocity is figured out for each object involved in a collision
+-- based on the properties of all objects involved in any specific interaction.
+-- That may not be how it works now, but the interface means it could work
+-- that way. Even more physical might be to figure out the impulsive force
+-- acting on each object.
+--
+-- However, the whole collision infrastructure should be revisited.
+--
+-- - Statefulness ("edge") might make it more robust.
+--
+-- - Think through how collision events are going to be communicated
+-- to the objects themselves. Maybe an input event is the natural
+-- thing to do. Except then we have to be careful to avoid switching
+-- again immediately after one switch.
+--
+-- - Should try to avoid n^2 checks. Maybe some kind of quad-trees?
+-- Maybe spawning a stateful collision detector when two objects are
+-- getting close? Cf. the old tail-gating approach.
+-- - Maybe a collision should also carry the identity of the object
+-- one collieded with to facilitate impl. of "inCollisionWith".
+--
+changedVelocity :: Eq n => n -> Collisions n -> Maybe Vel2D
+changedVelocity name cs =
+ case concatMap (filter ((== name) . fst) . collisionData) cs of
+ [] -> Nothing
+ (_, v') : _ -> Just v'
+ -- vs -> Just (foldl (^+^) (0,0) (map snd vs))
+
+-- | True if the velocity of the object has been changed by any collision.
+inCollision :: Eq n => n -> Collisions n -> Bool
+inCollision name cs = isJust (changedVelocity name cs)
+
+-- | True if the two objects are colliding with one another.
+inCollisionWith :: Eq n => n -> n -> Collisions n -> Bool
+inCollisionWith nm1 nm2 cs = any both cs
+ where
+ both (Collision nmvs) =
+ any ((== nm1) . fst) nmvs && any ((== nm2) . fst) nmvs
+
+-- * Apply an ID-based collision mask
+collisionMask :: Eq id
+ => id -> (id -> Bool) -> Collisions id -> Collisions id
+collisionMask cId mask = onCollisions ( filter (any (mask . fst))
+ . filter (any ((== cId).fst))
+ )
+
+ where onCollisions :: ([[(id, Vel2D)]] -> [[(id, Vel2D)]])
+ -> Collisions id -> Collisions id
+ onCollisions f = map Collision . f . map collisionData
diff --git a/src/Physics/TwoDimensions/Dimensions.hs b/src/Physics/TwoDimensions/Dimensions.hs
new file mode 100644
--- /dev/null
+++ b/src/Physics/TwoDimensions/Dimensions.hs
@@ -0,0 +1,9 @@
+-- | Physical dimensions used all over the game. They are just type synonyms,
+-- but it's best to use meaningful names to make our type signatures more
+-- meaningful.
+module Physics.TwoDimensions.Dimensions where
+
+type Size2D = (Double, Double)
+type Pos2D = (Double, Double)
+type Vel2D = (Double, Double)
+type Acc2D = (Double, Double)
diff --git a/src/Physics/TwoDimensions/GameCollisions.hs b/src/Physics/TwoDimensions/GameCollisions.hs
new file mode 100644
--- /dev/null
+++ b/src/Physics/TwoDimensions/GameCollisions.hs
@@ -0,0 +1,62 @@
+{-# LANGUAGE FlexibleContexts #-}
+-- | A very rudimentary collision system.
+--
+-- It compares every pair of objects, trying to determine if there is a
+-- collision between the two of them.
+--
+-- NOTE: In order to minimize the number of comparisons, only moving objects
+-- are tested (against every game object). That's only 2 objects right now
+-- (making it almost linear in complexity), but it could easily grow and become
+-- too slow.
+--
+module Physics.TwoDimensions.GameCollisions where
+
+import Data.Foldable
+import Prelude hiding (concatMap)
+import Data.List hiding (concatMap)
+import Data.Maybe
+import Physics.TwoDimensions.Collisions
+import qualified Physics.TwoDimensions.Collisions as C
+import Physics.TwoDimensions.PhysicalObjects
+import Physics.TwoDimensions.Shapes
+
+-- | Given a list of objects, it detects all the collisions between them.
+--
+-- Note: this is a simple n*m-complex algorithm, with n the
+-- number of objects and m the number of moving objects (right now,
+-- only 2).
+--
+detectCollisions :: Foldable t => (Eq n , PhysicalObject o n Shape) => t o -> Collisions n
+detectCollisions objsT = flattened
+ where -- Eliminate empty collision sets
+ -- TODO: why is this really necessary?
+ flattened = filter collisionNotEmpty collisions
+
+ -- Detect collisions between moving objects and any other objects
+ collisions = detectCollisions' objsT moving
+
+ -- Partition the object space between moving and static objects
+ (moving, _static) = partition physObjectCollides $ toList objsT
+
+ -- Is the collision set empty?
+ collisionNotEmpty (C.Collision n) = not (null n)
+
+-- | Detect collisions between each moving object and
+-- every other object.
+detectCollisions' :: (Foldable t, Foldable u) => (Eq n, PhysicalObject o n Shape) => t o -> u o -> [Collision n]
+detectCollisions' objsT ms = concatMap (detectCollisions'' objsT) ms
+
+-- | Detect collisions between one specific moving object and every existing
+-- object. Each collision is idependent of the rest (which is not necessarily
+-- what should happen, but since the transformed velocities are eventually
+-- added, there isn't much difference in the end).
+detectCollisions'' :: Foldable t => (Eq n, PhysicalObject o n Shape) => t o -> o -> [Collision n]
+detectCollisions'' objsT m = concatMap (detectCollisions''' m) (toList objsT)
+
+-- | Detect a possible collision between two objects. Uses the object's keys to
+-- distinguish them. Uses the basic 'Object'-based 'detectCollision' to
+-- determine whether the two objects do collide.
+detectCollisions''' :: (Eq n, PhysicalObject o n Shape) => o -> o -> [Collision n]
+detectCollisions''' m o
+ | physObjectId m == physObjectId o = [] -- Same object -> no collision
+ | otherwise = maybeToList (detectCollision m o)
diff --git a/src/Physics/TwoDimensions/PhysicalObjects.hs b/src/Physics/TwoDimensions/PhysicalObjects.hs
new file mode 100644
--- /dev/null
+++ b/src/Physics/TwoDimensions/PhysicalObjects.hs
@@ -0,0 +1,16 @@
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE FunctionalDependencies #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+module Physics.TwoDimensions.PhysicalObjects where
+
+import Physics.TwoDimensions.Dimensions
+
+class Eq b => PhysicalObject a b c | a -> b, a -> c where
+ physObjectPos :: a -> Pos2D
+ physObjectVel :: a -> Vel2D
+ physObjectElas :: a -> Double
+ physObjectShape :: a -> c
+ physObjectCollides :: a -> Bool
+ physObjectId :: a -> b
+ physObjectUpdatePos :: a -> Pos2D -> a
+ physObjectUpdateVel :: a -> Vel2D -> a
diff --git a/src/Physics/TwoDimensions/Shapes.hs b/src/Physics/TwoDimensions/Shapes.hs
new file mode 100644
--- /dev/null
+++ b/src/Physics/TwoDimensions/Shapes.hs
@@ -0,0 +1,66 @@
+-- | A very simple physics subsytem. It currently detects shape
+-- overlaps only, the actual physics movement is carried out
+-- in Yampa itself, as it is very simple using integrals and
+-- derivatives.
+module Physics.TwoDimensions.Shapes where
+
+import FRP.Yampa.VectorSpace
+import Physics.TwoDimensions.Dimensions
+
+import Constants
+import Collisions
+
+-- | Side of a rectangle
+data Side = TopSide | BottomSide | LeftSide | RightSide
+ deriving (Eq,Show)
+
+-- | Opposite side
+--
+-- If A collides with B, the collision sides on
+-- A and B are always opposite.
+oppositeSide :: Side -> Side
+oppositeSide TopSide = BottomSide
+oppositeSide BottomSide = TopSide
+oppositeSide LeftSide = RightSide
+oppositeSide RightSide = LeftSide
+
+data Shape = Rectangle Pos2D Size2D -- A corner and the whole size
+ | Circle Pos2D Double -- Position and radius
+ | SemiPlane Pos2D Side --
+
+-- | Detects if two shapes overlap.
+--
+-- Rectangles: overlap if projections on both axis overlap,
+-- which happens if x distance between centers is less than the sum
+-- of half the widths, and the analogous for y and the heights.
+
+overlapShape :: Shape -> Shape -> Bool
+overlapShape (Circle p1 s1) (Circle p2 s2) = (dist - (s1 + s2)) < sigma
+ where (dx, dy) = p2 ^-^ p1
+ dist = sqrt (dx**2 + dy**2)
+ sigma = 1
+overlapShape (Circle (p1x,p1y) s1) (SemiPlane (px,py) side) = case side of
+ LeftSide -> p1x - s1 <= px
+ RightSide -> p1x + s1 >= px
+ TopSide -> p1y - s1 <= py
+ BottomSide -> p1y + s1 >= py
+overlapShape s@(SemiPlane _ _) c@(Circle _ _) = overlapShape c s
+overlapShape r@(Rectangle _ _) c@(Circle _ _) = overlapShape c r
+overlapShape (Circle p1 s1) (Rectangle p2 s2) =
+ circleAABBOverlap (p1,s1) (rectangleToCentre (p2,s2))
+overlapShape (Rectangle p1 s1) (Rectangle p2 s2) =
+ overlapsAABB2 (rectangleToCentre (p1, s1)) (rectangleToCentre (p2, s2))
+overlapShape (Rectangle p1 s1) (SemiPlane p2 side2) =
+ let (p2', s2') = semiplaneRectangle p2 side2
+ in overlapsAABB2 (rectangleToCentre (p1, s1)) (rectangleToCentre (p2', s2'))
+overlapShape p@(SemiPlane _ _) r@(Rectangle _ _) = overlapShape r p
+overlapShape _ _ = False -- Not really, it's just that we don't care
+
+semiplaneRectangle :: Pos2D -> Side -> (Pos2D, (Double, Double))
+semiplaneRectangle p2 s2 = case s2 of
+ LeftSide -> (p2 ^-^ (100, 100), (100, height + 200))
+ RightSide -> (p2 ^-^ (0, 100), (100, height + 200))
+ TopSide -> (p2 ^-^ (100, 100), (width + 200, 100))
+ BottomSide -> (p2 ^-^ (100, 0), (width + 200, 100))
+
+rectangleToCentre ((px, py), (sw, sh)) = ((px + (sw / 2), py + (sh / 2)), (sw / 2, sh / 2))
diff --git a/src/Resources.hs b/src/Resources.hs
new file mode 100644
--- /dev/null
+++ b/src/Resources.hs
@@ -0,0 +1,10 @@
+module Resources where
+
+import qualified Graphics.UI.SDL.TTF as TTF
+
+-- import Game.Audio
+
+data Resources = Resources
+ { resFont :: TTF.Font
+ , miniFont :: TTF.Font
+ }