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{-
Pitfall14
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 program demonstrates pitfall 14 (Careful Enabling Color Material)
of Mark Kilgard's "16 Common OpenGL Pitfalls", see:
http://www.opengl.org/resources/features/KilgardTechniques/oglpitfall/
-}
import Control.Monad ( unless )
import System.Exit ( exitFailure )
import Graphics.UI.GLUT
main :: IO ()
main = do
(progName, _args) <- getArgsAndInitialize
initialDisplayMode $= [ SingleBuffered, RGBMode ]
createWindow progName
currentColor $= Color4 1 1 1 1
materialAmbient Front $= Color4 0.1 0.1 0.1 1
-- re-get to avoid any rounding issues
mafBefore <- get (materialAmbient Front)
colorMaterial $= Just (Front, Diffuse)
mafAfter <- get (materialAmbient Front)
unless (mafBefore == mafAfter) $ do
putStrLn "ERROR: The ambient material property changed!"
putStrLn (" before: " ++ show mafBefore)
putStrLn (" after : " ++ show mafAfter)
exitFailure
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