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module Scratchy.World where
import Data.List (partition)
import Control.Monad
import Graphics.Gloss.Interface.Pure.Game
import Scratchy.Syntax
-- Some useful helpers
------------------------------------------------------------
imapM :: Applicative m => (Int -> a -> m b) -> [a] -> m [b]
imapM f = zipWithM f [0..]
imapM_ :: Applicative m => (Int -> a -> m b) -> [a] -> m ()
imapM_ f xs = () <$ zipWithM f [0..] xs
setAt :: Int -> a -> [a] -> [a]
setAt i x xs = zipWith (\j y -> if i == j then x else y) [0..] xs
swap :: (a, b) -> (b, a)
swap (x, y) = (y, x)
-- Sprites
------------------------------------------------------------
data Sprite = Sprite
{ pic :: Picture
, pos :: Pos
, tgt :: Cell }
deriving (Show , Eq)
-- World
------------------------------------------------------------
data World = World
{ bg :: Color
, sprites :: ![Sprite]
, keysHeld :: ![Key]
, prog :: !(SProg ()) -- Current program
, keyHdlrs :: ![(Key, SProg ())] -- Key pressed
, trHdlrs :: ![( SpritePtr
, Cell
-> SProg () )] -- Target reached
, tuHdlrs :: ![( SpritePtr
, Cell
-> Cell
-> SProg () )] -- Target updated
, bhHdlrs :: ![( SpritePtr
, Cell
-> Cell
-> SProg () )] -- Barrier hit
, timers :: ![(Duration, SProg ())] -- Timers
}
-- Game
------------------------------------------------------------
newtype Game a = Game { runGame :: World -> (World, a) }
deriving Functor
instance Applicative Game where
pure x = Game $ \w -> (w,x)
(<*>) = ap
instance Monad Game where
Game f >>= k = Game $ \w ->
let (w', x) = f w in runGame (k x) w'
-- Sprite movement ops
------------------------------------------------------------
moveSprites :: Float -> Game ()
moveSprites dt = Game $ \w@World{..} ->
let (w', sprites') = flip runGame w $ imapM (moveSprite dt) sprites
in ( w' { sprites = sprites' }
, () )
moveSprite :: Float -> SpritePtr -> Sprite -> Game Sprite
moveSprite dt ptr m@Sprite{..} = Game $ \w@World{..} ->
let (tx,ty) = tgt
(px,py) = pos
dx = fromIntegral tx - px
dy = fromIntegral ty - py
dist = sqrt (dx*dx + dy*dy)
stepSize = cellsPerSec * dt
in if dist <= stepSize * dt
then ( w { prog
= prog `combine`
(case lookup ptr trHdlrs of
Just f -> f tgt
Nothing -> Pure ()) }
, m { pos = (fromIntegral tx, fromIntegral ty) } )
else ( w
, m { pos = ( px + (stepSize/dist)*dx
, py + (stepSize/dist)*dy ) } )
setSpriteTarget :: SpritePtr -> Cell -> Game ()
setSpriteTarget ptr c = Game $ \w@World{..} ->
let spr = sprites !! ptr in
if inBounds c
then ( w { sprites
= setAt ptr
(spr { tgt = c })
sprites
, prog
= prog `combine`
(case lookup ptr tuHdlrs of
Just f -> f (tgt spr) c
Nothing -> Pure ()) }
, () )
else ( w { prog
= prog `combine`
(case lookup ptr bhHdlrs of
Just f -> f (tgt spr) c
Nothing -> Pure ()) }
, () )
spriteExistsAt :: Cell -> [Sprite] -> Maybe SpritePtr
spriteExistsAt c = go . zip [0..]
where
go [] = Nothing
go ((p,s):sprs) =
let (p1, p2) = pos s
c' = (round p1, round p2)
in if c == c' || c == tgt s then Just p else go sprs
-- Input handling
------------------------------------------------------------
handleEvent :: Event -> Game ()
handleEvent (EventKey c d _ _) = case d of
Down -> press c
Up -> release c
handleEvent _ = pure ()
press :: Key -> Game ()
press d = Game $ \w@World{..} ->
( w { keysHeld = d : filter (/= d) keysHeld }
, () )
release :: Key -> Game ()
release d = Game $ \w@World{..} ->
( w { keysHeld = filter (/= d) keysHeld }
, () )
handleKeyEvents :: Game ()
handleKeyEvents = Game $ \w@World{..} ->
( fst
$ flip runGame w
$ mapM_ handleKey keysHeld
, () )
handleKey :: Key -> Game ()
handleKey k = Game $ \w@World{..} ->
( w { prog
= prog `combine`
(case lookup k keyHdlrs of
Just m -> m
Nothing -> Pure ()) }
, () )
-- Timers
------------------------------------------------------------
tickTimers :: Game ()
tickTimers = Game $ \w@World{..} ->
let ts = map (\(d,m) -> (d-1,m)) timers
(done,remaining) = partition (\(d,_) -> d <= 0) ts
p' = foldr (\(_,m) -> combine m) (Pure ()) done
in ( w { timers = remaining
, prog = prog `combine` p' }
, () )
-- Running programs
------------------------------------------------------------
runProg :: Game ()
runProg = Game $ \w -> (go (prog w) w { prog = Pure () } , ())
where
go :: SProg () -> World -> World
go = undefined -- Fill this in
|