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{-
Double.hs (adapted from double.c which is (c) Silicon Graphics, Inc.)
Copyright (c) Sven Panne 2002-2005 <sven.panne@aedion.de>
This file is part of HOpenGL and distributed under a BSD-style license
See the file libraries/GLUT/LICENSE
This is a simple double buffered program.
Pressing the left mouse button rotates the rectangle.
Pressing the middle mouse button stops the rotation.
-}
import Data.IORef ( IORef, newIORef )
import System.Exit ( exitWith, ExitCode(ExitSuccess) )
import Graphics.UI.GLUT
data State = State { spin :: IORef GLfloat }
makeState :: IO State
makeState = do
s <- newIORef 0
return $ State { spin = s }
display :: State -> DisplayCallback
display state = do
clear [ ColorBuffer ]
preservingMatrix $ do
s <- get (spin state)
rotate s (Vector3 0 0 1)
color (Color3 1 1 1 :: Color3 GLfloat)
rect (Vertex2 (-25) (-25)) (Vertex2 25 25 :: Vertex2 GLfloat)
swapBuffers
spinDisplay :: State -> IdleCallback
spinDisplay state = do
let wrap n s = if s > n then s - n else s
spin state $~ (wrap 360 . (+ 2))
postRedisplay Nothing
myInit :: IO ()
myInit = do
clearColor $= Color4 0 0 0 0
shadeModel $= Flat
reshape :: ReshapeCallback
reshape size = do
viewport $= (Position 0 0, size)
matrixMode $= Projection
loadIdentity
ortho (-50) 50 (-50) 50 (-1) 1
matrixMode $= Modelview 0
loadIdentity
keyboardMouse :: State -> KeyboardMouseCallback
keyboardMouse state (MouseButton b) Down _ _ =
idleCallback $= case b of
LeftButton -> Just (spinDisplay state)
_ -> Nothing
-- ESC not handled in the original example, but useful nevertheless
keyboardMouse _ (Char '\27') Down _ _ = exitWith ExitSuccess
keyboardMouse _ _ _ _ _ = return ()
-- Request double buffer display mode.
-- Register mouse input callback functions
main :: IO ()
main = do
(progName, _args) <- getArgsAndInitialize
initialDisplayMode $= [ DoubleBuffered, RGBMode ]
initialWindowSize $= Size 250 250
initialWindowPosition $= Position 100 100
createWindow progName
state <- makeState
myInit
displayCallback $= display state
reshapeCallback $= Just reshape
keyboardMouseCallback $= Just (keyboardMouse state)
mainLoop
|
