59 lines
1.4 KiB
Haskell
59 lines
1.4 KiB
Haskell
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module Graphics.GlossUtils (playYampa, InputEvent) where
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-- A utility function to connect the FRP library Yampa to the
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-- graphics library Gloss, from the library yampa-gloss
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import Control.Monad (when)
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import Data.IORef
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( newIORef,
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readIORef,
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writeIORef,
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)
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import FRP.Yampa
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( Event (..),
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SF,
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react,
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reactInit,
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)
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import Graphics.Gloss
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( Color,
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Display,
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Picture,
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blank,
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)
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import qualified Graphics.Gloss
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import Graphics.Gloss.Interface.IO.Game (playIO)
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import qualified Graphics.Gloss.Interface.IO.Game as G
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type InputEvent = G.Event
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playYampa ::
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-- | The display method
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Display ->
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-- | The background color
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Color ->
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-- | The refresh rate, in Hertz
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Int ->
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SF (Event InputEvent) Picture ->
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IO ()
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playYampa display color frequency mainSF = do
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picRef <- newIORef blank
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handle <-
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reactInit
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(return NoEvent)
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( \_ updated pic ->
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when updated (picRef `writeIORef` pic) >> return False
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)
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mainSF
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let delta = 0.01 / fromIntegral frequency
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toPic = const $ readIORef picRef
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handleInput = (\e t -> react handle (delta, Just (Event e)) >> return (t + delta))
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stepWorld =
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( \d t ->
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let delta' = realToFrac d - t
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in if delta' > 0
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then react handle (delta', Just NoEvent) >> return 0.0
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else return (- delta')
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)
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playIO display color frequency 0 toPic handleInput stepWorld
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