ansi-terminal-game-1.9.4.0: src/Terminal/Game/Layer/Imperative.hs
-------------------------------------------------------------------------------
-- Layer 1 (imperative), as per
-- https://www.parsonsmatt.org/2018/03/22/three_layer_haskell_cake.html
-- 2019 Francesco Ariis GPLv3
-------------------------------------------------------------------------------
{-# Language ScopedTypeVariables #-}
module Terminal.Game.Layer.Imperative where
import Terminal.Game.Draw
import Terminal.Game.Layer.Object
import qualified Control.Concurrent as CC
import qualified Control.Exception as E
import qualified Control.Monad as CM
import qualified Data.Bool as B
import qualified Data.Either as ET
import qualified Data.List as D
import qualified System.IO as SI
import Terminal.Game.Plane
-- | Game definition datatype, parametrised on:
--
-- * your gamestate @s@; and
-- * a result when the game is finished @r@. Simple games do not need this,
-- just fill @r@ with @()@.
--
-- The two most important elements are the function dealing with logic and
-- the drawing one. Check @alone@ demo (@cabal run -f examples alone@) to
-- see a basic game in action.
data Game s r = Game {
gTPS :: TPS,
-- ^ Game speed in ticks per second. You do not
-- need high values, since the 2D canvas is coarse
-- (e.g. 13 TPS is enough for action games).
gInitState :: s, -- ^ Initial state of the game.
gLogicFunction :: GEnv -> s -> Event -> Either r s,
-- ^ Logic function. If `gLogicFunction` returns @Right s@
-- the game will continue with state @s@; if it returns @Left@
-- the game is over (quit condition).
--
-- Curious to see how @r@ can be useful? Check
-- @cabal run -f examples balls@ and
-- @example/MainBalls.hs@.
gDrawFunction :: GEnv -> s -> Plane
-- ^ Draw function. Just want to blit your game
-- in the middle? Check 'centerFull'.
}
-- | A blank plane as big as the terminal.
blankPlaneFull :: GEnv -> Plane
blankPlaneFull e = uncurry blankPlane (eTermDims e)
-- | Blits plane in the middle of terminal.
--
-- @
-- draw :: GEnv -> MyState -> Plane
-- draw ev s =
-- centerFull ev $
-- ⁝
-- @
centerFull :: GEnv -> Plane -> Plane
centerFull e p = blankPlaneFull e *** p
-- | Entry point for the game execution, should be called in @main@.
--
-- You __must__ compile your programs with @-threaded@; if you do not do
-- this the game will crash, at start-up. Just add:
--
-- @
-- ghc-options: -threaded
-- @
--
-- in your @.cabal@ file and you will be fine!
playGame :: Game s r -> IO r
playGame g = either id (error "`Right` in playGame") <$>
runGIO (runGameGeneral g)
-- | As 'playGame', but ignore the result @r@.
playGame_ :: Game s r -> IO ()
playGame_ g = () <$ playGame g
-- | Tests a game in a /pure/ environment. Aims to accurately emulate 'GEnv'
-- changes (screen size, FPS) too. Returns a result @r@ or a state @s@ in
-- case the Event stream is exhausted before the game exits.
--
-- A useful trick is to call 'recordGame' and press /Ctrl-C/ while playing
-- (instead of quitting properly). This way @testGame@ will return
-- @Left s@, a state that you can then inspect.
testGame :: Game s r -> GRec -> Either r s
testGame g ts =
case runTest (runGameGeneral g) ts of
(Nothing, l) -> error $ "testGame, exception called: " ++
show l
-- it is fine to use error here since in the end
-- hspec can deal with it gracefully and we give
-- more infos on a failed test
(Just s, _) -> s
-- | As 'testGame', but returns 'Game' instead of result/state.
-- Useful to fast-forward (e.g.: skip menus) before invoking 'playGame'.
setupGame :: Game s r -> GRec -> Game s r
setupGame g ts = let s' = testGame g ts
in case s' of
-- If the game is already over, return a mock logic
-- function which simply ends the game.
Left r -> g { gLogicFunction = \_ _ _ -> Left r }
Right s -> g { gInitState = s }
-- | Similar to 'testGame', runs the game given a 'GRec'. Unlike
-- 'testGame', the playthrough will be displayed on screen. Useful when a
-- test fails and you want to see how.
--
-- See this in action with @cabal run -f examples alone-playback@.
--
-- Notice that 'GEnv' will be provided at /run-time/, and not
-- record-time; this can make emulation slightly inaccurate if — e.g. —
-- you replay the game on a smaller terminal than the one you recorded
-- the session on.
narrateGame :: Game s r -> GRec -> IO ()
narrateGame g e = () <$ runReplay (runGameGeneral g) e
-- | Play as in 'playGame' and write the session (input stream, etc.) to
-- @file@. Then you can use this with 'testGame' and 'narrateGame'. Session
-- will be recorded even if an exception happens while playing.
recordGame :: Game s r -> FilePath -> IO ()
recordGame g fp =
E.bracket
(CC.newMVar igrec)
(\ve -> writeRec fp ve)
(\ve -> () <$ runRecord (runGameGeneral g) ve)
data Config = Config { cMEvents :: CC.MVar [Event],
cTPS :: TPS }
runGameGeneral :: forall s r m. MonadGameIO m =>
Game s r -> m (Either r s)
runGameGeneral (Game tps s lf df) =
-- init
setupDisplay >>
startEvents tps >>= \(InputHandle ve ts) ->
displaySizeErr >>= \ds ->
-- do it!
let c = Config ve tps in
cleanUpErr (game c ds)
-- this under will be run regardless
(stopEvents ts >>
shutdownDisplay )
where
game :: MonadGameIO m => Config -> Dimensions -> m (Either r s)
game c wds = gameLoop c (Right s) lf df
Nothing wds
(creaFPSCalc tps)
-- | Wraps an @IO@ computation so that any 'ATGException' or 'error' gets
-- displayed along with a @\<press any key to quit\>@ prompt.
-- Some terminals shut-down immediately upon program end; adding
-- @errorPress@ to 'playGame' makes it easier to beta-test games on those
-- terminals.
errorPress :: IO a -> IO a
errorPress m = E.catches m [E.Handler errorDisplay,
E.Handler atgDisplay]
where
errorDisplay :: E.ErrorCall -> IO a
errorDisplay (E.ErrorCallWithLocation cs l) = report $
putStrLn (cs ++ "\n\n") >>
putStrLn "Stack trace info:\n" >>
putStrLn l
atgDisplay :: ATGException -> IO a
atgDisplay e = report $ print e
report :: IO () -> IO a
report wm =
putStrLn "ERROR REPORT\n" >>
wm >>
putStrLn "\n\n <Press any key to quit>" >>
SI.hSetBuffering SI.stdin SI.NoBuffering >>
getChar >>
errorWithoutStackTrace "errorPress"
-----------
-- LOGIC --
-----------
-- from http://www.loomsoft.net/resources/alltut/alltut_lesson6.htm
gameLoop :: MonadGameIO m =>
Config -> -- event source
Either r s -> -- state
(GEnv ->
s -> Event ->
Either r s) -> -- logic function
(GEnv ->
s -> Plane) -> -- draw function
Maybe Plane -> -- last blitted screen
Dimensions -> -- Term dimensions
FPSCalc -> -- calculate fps
m (Either r s)
gameLoop c s lf df opln td fps =
-- Quit?
areEventsOver >>= \qb ->
-- We will quit in case input stream (events) is exhausted.
-- This might happen during test/narrate.
if ET.isLeft s || qb
then return s
else
-- Fetch events (if any).
-- This is safe as we checked for `areEventsOver` above.
pollEvents (cMEvents c) >>= \es ->
-- no events? skip everything
if null es
then sleepABit (cTPS c) >>
gameLoop c s lf df opln td fps
else
displaySizeErr >>= \td' ->
-- logic
let ge = GEnv td' (calcFPS fps)
(i, s') = stepsLogic s (lf ge) es in
-- no `Tick` events? You do not need to blit, just update state
if i == 0
then gameLoop c s' lf df opln td fps
else
-- FPS calc
let fps' = addFPS i fps in
-- clear screen if resolution changed
let resc = td /= td' in
CM.when resc clearDisplay >>
-- draw
let
opln' | resc = Nothing -- res changed? restart double buffering
| otherwise = opln
npln = case s' of
(Right rs) -> df ge rs
(Left _) -> uncurry blankPlane td'
-- In case the logic function came to an end
-- (Left), just print a blank plane.
in
blitPlane opln' npln >>
gameLoop c s' lf df (Just npln) td' fps'
-- Int = number of `Tick` events
stepsLogic :: Either r s -> (s -> Event -> Either r s) -> [Event] ->
(Integer, Either r s)
stepsLogic s lf es = let ies = D.genericLength . filter isTick $ es
in (ies, logicFold lf s es)
where
isTick Tick = True
isTick _ = False
logicFold :: (s -> Event -> Either r s) ->
Either r s -> [Event] -> Either r s
logicFold _ (Left r) _ = Left r
logicFold wlf (Right ws) wes = CM.foldM wlf ws wes
-------------------------------------------------------------------------------
-- Frame per Seconds
data FPSCalc = FPSCalc [Integer] TPS
-- list with number of `Ticks` processed at each blit and expected
-- FPS (i.e. TPS)
-- the size of moving average will be TPS (that simplifies calculations)
creaFPSCalc :: TPS -> FPSCalc
creaFPSCalc tps = FPSCalc (D.genericReplicate tps {- (tps*2) -} 1) tps
-- tps*1: size of thw window in **blit actions** (not tick actions!)
-- so keeping it small should be responsive and non flickery
-- at the same time!
-- add ticks
addFPS :: Integer -> FPSCalc -> FPSCalc
addFPS nt (FPSCalc (_:fps) tps) = FPSCalc (fps ++ [nt]) tps
addFPS _ (FPSCalc [] _) = error "addFPS: empty list."
calcFPS :: FPSCalc -> Integer
calcFPS (FPSCalc fps tps) =
let ts = sum fps
ds = D.genericLength fps
in roundQuot (tps * ds) ts
where
roundQuot :: Integer -> Integer -> Integer
roundQuot a b = let (q, r) = quotRem a b
in q + B.bool 0 1 (r > div b 2)