/usr/share/doc/libghc-glut-doc/examples/RedBook/Mipmap.hs is in libghc-glut-doc 2.4.0.0-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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Mipmap.hs (adapted from mipmap.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 program demonstrates using mipmaps for texture maps. To overtly show
the effect of mipmaps, each mipmap reduction level has a solidly colored,
contrasting texture image. Thus, the quadrilateral which is drawn is drawn
with several different colors.
-}
import Control.Monad ( when )
import Data.Maybe ( isJust, listToMaybe )
import Foreign ( withArray )
import System.Exit ( exitWith, ExitCode(ExitSuccess) )
import Graphics.UI.GLUT
makeImage :: Level -> TextureSize2D -> Color4 GLubyte -> IO ()
makeImage level size@(TextureSize2D w h) col =
withArray (replicate (fromIntegral (w * h)) col) $
texImage2D Nothing NoProxy level RGBA' size 0 . PixelData RGBA UnsignedByte
makeImages :: [Color4 GLubyte] -> IO ()
makeImages colors = sequence_ $ zipWith3 makeImage levels sizes colors
where numLevels = length colors
levels = [ 0 .. fromIntegral numLevels - 1 ]
sizes = reverse (take numLevels [ TextureSize2D s s | s <- iterate (* 2) 1 ])
myInit :: IO (Maybe TextureObject)
myInit = do
depthFunc $= Just Less
shadeModel $= Flat
translate (Vector3 0 0 (-3.6 :: GLfloat))
rowAlignment Unpack $= 1
exts <- get glExtensions
mbTexName <- if "GL_EXT_texture_object" `elem` exts
then fmap listToMaybe $ genObjectNames 1
else return Nothing
when (isJust mbTexName) $ textureBinding Texture2D $= mbTexName
textureWrapMode Texture2D S $= (Repeated, Repeat)
textureWrapMode Texture2D T $= (Repeated, Repeat)
textureFilter Texture2D $= ((Nearest, Just Nearest), Nearest)
makeImages [ Color4 255 255 0 255,
Color4 255 0 255 255,
Color4 255 0 0 255,
Color4 0 255 0 255,
Color4 0 0 255 255,
Color4 255 255 255 255 ]
textureFunction $= Decal
texture Texture2D $= Enabled
return mbTexName
display :: Maybe TextureObject -> DisplayCallback
display mbTexName = do
clear [ ColorBuffer, DepthBuffer ]
when (isJust mbTexName) $ textureBinding Texture2D $= mbTexName
-- resolve overloading, not needed in "real" programs
let texCoord2f = texCoord :: TexCoord2 GLfloat -> IO ()
vertex3f = vertex :: Vertex3 GLfloat -> IO ()
renderPrimitive Quads $ do
texCoord2f (TexCoord2 0 0); vertex3f (Vertex3 ( -2) (-1) 0 )
texCoord2f (TexCoord2 0 8); vertex3f (Vertex3 ( -2) 1 0 )
texCoord2f (TexCoord2 8 8); vertex3f (Vertex3 2000 1 (-6000))
texCoord2f (TexCoord2 8 0); vertex3f (Vertex3 2000 (-1) (-6000))
flush
reshape :: ReshapeCallback
reshape size@(Size w h) = do
viewport $= (Position 0 0, size)
matrixMode $= Projection
loadIdentity
perspective 60 (fromIntegral w / fromIntegral h) 1 30000
matrixMode $= Modelview 0
loadIdentity
keyboard :: KeyboardMouseCallback
keyboard (Char '\27') Down _ _ = exitWith ExitSuccess
keyboard _ _ _ _ = return ()
main :: IO ()
main = do
(progName, _args) <- getArgsAndInitialize
initialDisplayMode $= [ SingleBuffered, RGBMode, WithDepthBuffer ]
initialWindowSize $= Size 500 500
initialWindowPosition $= Position 50 50
createWindow progName
texName <- myInit
displayCallback $= display texName
reshapeCallback $= Just reshape
keyboardMouseCallback $= Just keyboard
mainLoop
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