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{-
MoveLight.hs (adapted from movelight.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 when to issue lighting and transformation
commands to render a model with a light which is moved by a
modeling transformation (rotate or translate). The light position
is reset after the modeling transformation is called. The eye
position does not change.
A sphere is drawn using a grey material characteristic. A single
light source illuminates the object.
Interaction: pressing the left mouse button alters the modeling
transformation (x rotation) by 30 degrees. The scene is then
redrawn with the light in a new position.
-}
import Data.IORef ( IORef, newIORef )
import System.Exit ( exitWith, ExitCode(ExitSuccess) )
import Graphics.UI.GLUT
data State = State { spin :: IORef Int }
makeState :: IO State
makeState = do
s <- newIORef 0
return $ State { spin = s }
myInit :: IO ()
myInit = do
clearColor $= Color4 0 0 0 0
shadeModel $= Smooth
lighting $= Enabled
light (Light 0) $= Enabled
depthFunc $= Just Less
display :: State -> DisplayCallback
display state = do
clear [ ColorBuffer, DepthBuffer ]
preservingMatrix $ do
lookAt (Vertex3 0 0 5) (Vertex3 0 0 0) (Vector3 0 1 0)
preservingMatrix $ do
s <- get (spin state)
rotate (fromIntegral s :: GLdouble) (Vector3 1 0 0)
position (Light 0) $= Vertex4 0 0 1.5 1
translate (Vector3 0 0 1.5 :: Vector3 GLdouble)
lighting $= Disabled
color (Color3 0 1 1 :: Color3 GLfloat)
renderObject Wireframe (Cube 0.1)
lighting $= Enabled
renderObject Solid (Torus 0.275 0.85 8 15)
flush
reshape :: ReshapeCallback
reshape size@(Size w h) = do
viewport $= (Position 0 0, size)
matrixMode $= Projection
loadIdentity
perspective 40 (fromIntegral w / fromIntegral h) 1 20
matrixMode $= Modelview 0
loadIdentity
keyboardMouse :: State -> KeyboardMouseCallback
keyboardMouse state (MouseButton LeftButton) Down _ _ = do
spin state $~ ((`mod` 360) . (+ 30))
postRedisplay Nothing
keyboardMouse _ (Char '\27') Down _ _ = exitWith ExitSuccess
keyboardMouse _ _ _ _ _ = return ()
main :: IO ()
main = do
(progName, _args) <- getArgsAndInitialize
initialDisplayMode $= [ SingleBuffered, RGBMode, WithDepthBuffer ]
initialWindowSize $= Size 500 500
initialWindowPosition $= Position 100 100
createWindow progName
state <- makeState
myInit
displayCallback $= display state
reshapeCallback $= Just reshape
keyboardMouseCallback $= Just (keyboardMouse state)
mainLoop
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