/usr/share/doc/libghc-glut-doc/examples/RedBook/Trim.hs is in libghc-glut-doc 2.1.2.2-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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Trim.hs (adapted from trim.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 draws a NURBS surface in the shape of a symmetrical hill,
using both a NURBS curve and pwl (piecewise linear) curve to trim part
of the surface.
NOTE: This example does NOT demonstrate the final NURBS API, it's currently
just a test for the internals...
-}
import Foreign.Marshal ( withArray )
import System.Exit ( exitWith, ExitCode(ExitSuccess) )
import Graphics.UI.GLUT
-- The control points of the surface form a small hill and
-- range from -3 to +3 in x, y, and z.
ctlPoints :: [[Vertex3 GLfloat]]
ctlPoints =
[ [ Vertex3 (2 * u - 3)
(2 * v - 3)
(if (u == 1 || u ==2) && (v == 1 || v == 2) then 3 else -3)
| v <- [ 0 .. 3 ] ]
| u <- [ 0 .. 3 ]]
myInit :: IO ()
myInit = do
clearColor $= Color4 0 0 0 0
materialDiffuse Front $= Color4 0.7 0.7 0.7 1
materialSpecular Front $= Color4 1 1 1 1
materialShininess Front $= 100
lighting $= Enabled
light (Light 0) $= Enabled
depthFunc $= Just Less
autoNormal $= Enabled
normalize $= Enabled
--------------------------------------------------------------------------------
display :: DisplayCallback
display = do
let knots = [ 0, 0, 0, 0, 1, 1, 1, 1 ] :: [GLfloat]
edgePt = -- counter clockwise
[ Vertex2 0 0, Vertex2 1 0, Vertex2 1 1, Vertex2 0 1, Vertex2 0 0 ] :: [Vertex2 GLfloat]
curvePt = -- clockwise
[ Vertex2 0.25 0.5, Vertex2 0.25 0.75, Vertex2 0.75 0.75, Vertex2 0.75 0.5 ] :: [Vertex2 GLfloat]
curveKnots =
[ 0, 0, 0, 0, 1, 1, 1, 1 ] :: [GLfloat]
pwlPt = -- clockwise
[Vertex2 0.75 0.5, Vertex2 0.5 0.25, Vertex2 0.25 0.5 ] :: [Vertex2 GLfloat]
clear [ ColorBuffer, DepthBuffer ]
preservingMatrix $ do
rotate (330 :: GLfloat) (Vector3 1 0 0)
scale 0.5 0.5 (0.5 :: GLfloat)
withNURBSObj () $ \nurbsObj -> do
setSamplingMethod nurbsObj (PathLength 25)
setDisplayMode' nurbsObj Fill'
checkForNURBSError nurbsObj $
nurbsBeginEndSurface nurbsObj $
withArray (concat ctlPoints) $ \cBuf ->
withArray knots $ \kBuf -> do
nurbsSurface nurbsObj 8 kBuf 8 kBuf (4 * 3) 3 cBuf 4 4
nurbsBeginEndTrim nurbsObj $
withArray edgePt $ \edgePtBuf ->
pwlCurve nurbsObj 5 edgePtBuf 2
nurbsBeginEndTrim nurbsObj $ do
withArray curveKnots $ \curveKnotsBuf ->
withArray curvePt $ \curvePtBuf ->
trimmingCurve nurbsObj 8 curveKnotsBuf 2 curvePtBuf 4
withArray pwlPt $ \pwlPtBuf ->
pwlCurve nurbsObj 3 pwlPtBuf 2
flush
reshape :: ReshapeCallback
reshape size@(Size w h) = do
viewport $= (Position 0 0, size)
matrixMode $= Projection
loadIdentity
perspective 45 (fromIntegral w / fromIntegral h) 3 8
matrixMode $= Modelview 0
loadIdentity
translate (Vector3 0 0 (-5 :: GLfloat))
keyboard :: KeyboardMouseCallback
keyboard (Char '\27') Down _ _ = exitWith ExitSuccess
keyboard _ _ _ _ = return ()
-- Main Loop
main :: IO ()
main = do
(progName, _args) <- getArgsAndInitialize
initialDisplayMode $= [ SingleBuffered, RGBMode, WithDepthBuffer ]
initialWindowSize $= Size 500 500
initialWindowPosition $= Position 100 100
createWindow progName
myInit
reshapeCallback $= Just reshape
displayCallback $= display
keyboardMouseCallback $= Just keyboard
mainLoop
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