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{-
Planet.hs (adapted from planet.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 shows how to composite modeling transformations to draw
translated and rotated models. Interaction: pressing the d and y keys
(day and year) alters the rotation of the planet around the sun.
-}
import Data.IORef ( IORef, newIORef )
import System.Exit ( exitWith, ExitCode(ExitSuccess) )
import Graphics.UI.GLUT
data State = State { year, day :: IORef GLint }
makeState :: IO State
makeState = do
y <- newIORef 0
d <- newIORef 0
return $ State { year = y, day = d }
myInit :: IO ()
myInit = do
clearColor $= Color4 0 0 0 0
shadeModel $= Flat
display :: State -> DisplayCallback
display state = do
clear [ ColorBuffer ]
-- resolve overloading, not needed in "real" programs
let color3f = color :: Color3 GLfloat -> IO ()
translatef = translate :: Vector3 GLfloat -> IO ()
color3f (Color3 1 1 1)
preservingMatrix $ do
renderObject Wireframe (Sphere' 1 20 16) -- draw sun
y <- get (year state)
rotate (fromIntegral y :: GLfloat) (Vector3 0 1 0)
translatef (Vector3 2 0 0)
d <- get (day state)
rotate (fromIntegral d :: GLfloat) (Vector3 0 1 0)
renderObject Wireframe (Sphere' 0.2 10 8) -- draw smaller planet
swapBuffers
reshape :: ReshapeCallback
reshape size@(Size w h) = do
viewport $= (Position 0 0, size)
matrixMode $= Projection
loadIdentity
perspective 60 (fromIntegral w / fromIntegral h) 1 20
matrixMode $= Modelview 0
loadIdentity
lookAt (Vertex3 0 0 5) (Vertex3 0 0 0) (Vector3 0 1 0)
keyboard :: State -> KeyboardMouseCallback
keyboard state (Char c) Down _ _ = case c of
'd' -> update day 10
'D' -> update day (-10)
'y' -> update year 10
'Y' -> update year (-10)
'\27' -> exitWith ExitSuccess
_ -> return ()
where update angle inc = do
angle state $~ ((`mod` 360) . (+ inc))
postRedisplay Nothing
keyboard _ _ _ _ _ = return ()
main :: IO ()
main = do
(progName, _args) <- getArgsAndInitialize
initialDisplayMode $= [ DoubleBuffered, RGBMode ]
initialWindowSize $= Size 500 500
initialWindowPosition $= Position 100 100
createWindow progName
state <- makeState
myInit
displayCallback $= display state
reshapeCallback $= Just reshape
keyboardMouseCallback $= Just (keyboard state)
mainLoop
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