brillo-examples-1.13.3: picture/Occlusion/State.hs

{-# LANGUAGE PatternGuards #-}

module State where

import Brillo.Interface.Pure.Game
import World


-- | The game state.
data State
  = State
  { stateWorld :: World
  , stateLineStart :: Point
  , stateLineEnd :: Point
  }


-- | Initial game state.
initState :: World -> State
initState world =
  State
    { stateWorld = world
    , stateLineStart = (10, 10)
    , stateLineEnd = (10, 10)
    }


-- | Handle an input event.
handleInput :: World -> Event -> State -> State
handleInput world (EventKey key keyState mods pos) state
  | MouseButton LeftButton <- key
  , Down <- keyState
  , shift mods == Down =
      state{stateLineEnd = worldPosOfWindowPos world pos}
  | MouseButton LeftButton <- key
  , Down <- keyState =
      state
        { stateLineStart = worldPosOfWindowPos world pos
        , stateLineEnd = worldPosOfWindowPos world pos
        }
  | MouseButton RightButton <- key
  , Down <- keyState =
      state{stateLineEnd = worldPosOfWindowPos world pos}
handleInput _ _ state =
  state