--
-- This code was created by Jeff Molofee '99 (ported to Haskell GHC 2005)
--
module Main where
import Graphics.UI.GLUT
import System.Exit ( exitWith, ExitCode(..) )
import Monad ( liftM )
import Data.IORef ( IORef, newIORef )
import Util ( Image(..), bitmapLoad )
initGL :: IO TextureObject
initGL = do
tex <- loadGLTextures
texture Texture2D $= Enabled
clearColor $= Color4 0 0 0 0.5 -- Clear the background color to black
clearDepth $= 1 -- enables clearing of the depth buffer
depthFunc $= Just Less -- type of depth test
shadeModel $= Smooth -- enables smooth color shading
matrixMode $= Projection
loadIdentity -- reset projection matrix
Size width height <- get windowSize
perspective 45 (fromIntegral width/fromIntegral height) 0.1 100 -- calculate the aspect ratio of the window
matrixMode $= Modelview 0
flush -- finally, we tell opengl to do it.
return tex
loadGLTextures :: IO TextureObject
loadGLTextures = do
(Image (Size w h) pd) <- bitmapLoad "Data/NeHe.bmp"
texName <- liftM head (genObjectNames 1)
textureBinding Texture2D $= Just texName
textureFilter Texture2D $= ((Nearest, Nothing), Nearest)
texImage2D Nothing NoProxy 0 RGB' (TextureSize2D w h) 0 pd
return texName
resizeScene :: Size -> IO ()
resizeScene (Size w 0) = resizeScene (Size w 1) -- prevent divide by zero
resizeScene s@(Size width height) = do
viewport $= (Position 0 0, s)
matrixMode $= Projection
loadIdentity
perspective 45 (fromIntegral width/fromIntegral height) 0.1 100
matrixMode $= Modelview 0
flush
drawScene :: TextureObject -> IORef GLfloat -> IORef GLfloat
-> IORef GLfloat -> IO ()
drawScene tex xrot yrot zrot = do
clear [ColorBuffer, DepthBuffer] -- clear the screen and the depth bufer
loadIdentity -- reset view
translate (Vector3 0 0 (-5.0::GLfloat)) --Move left 5 Units into the screen
xr <- get xrot
yr <- get yrot
zr <- get zrot
rotate xr (Vector3 1 0 (0::GLfloat)) -- Rotate the triangle on the Y axis
rotate yr (Vector3 0 1 (0::GLfloat)) -- Rotate the triangle on the Y axis
rotate zr (Vector3 0 0 (1::GLfloat)) -- Rotate the triangle on the Y axis
textureBinding Texture2D $= Just tex
renderPrimitive Quads $ -- start drawing a polygon (4 sided)
do
-- first the front
texCoord (TexCoord2 0 (0::GLfloat))
vertex (Vertex3 (-1) (-1) (1::GLfloat)) -- bottom left of quad (Front)
texCoord (TexCoord2 1 (0::GLfloat))
vertex (Vertex3 1 (-1) (1::GLfloat)) -- bottom right of quad (Front)
texCoord (TexCoord2 1 (1::GLfloat))
vertex (Vertex3 1 1 (1::GLfloat)) -- top right of quad (Front)
texCoord (TexCoord2 0 (1::GLfloat))
vertex (Vertex3 (-1) 1 (1::GLfloat)) -- top left of quad (Front)
-- now the back
texCoord (TexCoord2 1 (0::GLfloat))
vertex (Vertex3 (-1) (-1) (-1::GLfloat)) -- bottom right of quad (Back)
texCoord (TexCoord2 1 (1::GLfloat))
vertex (Vertex3 (-1) 1 (-1::GLfloat)) -- top right of quad (Back)
texCoord (TexCoord2 0 (1::GLfloat))
vertex (Vertex3 1 1 (-1::GLfloat)) -- top left of quad (Back)
texCoord (TexCoord2 0 (0::GLfloat))
vertex (Vertex3 1 (-1) (-1::GLfloat)) -- bottom left of quad (Back)
-- now the top
texCoord (TexCoord2 0 (1::GLfloat))
vertex (Vertex3 (-1) 1 (-1::GLfloat)) -- top left of quad (Top)
texCoord (TexCoord2 0 (0::GLfloat))
vertex (Vertex3 (-1) 1 (1::GLfloat)) -- bottom left of quad (Top)
texCoord (TexCoord2 1 (0::GLfloat))
vertex (Vertex3 1 1 (1::GLfloat)) -- bottom right of quad (Top)
texCoord (TexCoord2 1 (1::GLfloat))
vertex (Vertex3 1 1 (-1::GLfloat)) -- top right of quad (Top)
-- now the bottom
texCoord (TexCoord2 1 (1::GLfloat))
vertex (Vertex3 1 (-1) (1::GLfloat)) -- top right of quad (Bottom)
texCoord (TexCoord2 0 (1::GLfloat))
vertex (Vertex3 (-1) (-1) (1::GLfloat)) -- top left of quad (Bottom)
texCoord (TexCoord2 0 (0::GLfloat))
vertex (Vertex3 (-1) (-1) (-1::GLfloat)) -- bottom left of quad (Bottom)
texCoord (TexCoord2 1 (0::GLfloat))
vertex (Vertex3 1 (-1) (-1::GLfloat)) -- bottom right of quad (Bottom)
-- now the right
texCoord (TexCoord2 1 (0::GLfloat))
vertex (Vertex3 1 (-1) (-1::GLfloat)) -- bottom right of quad (Right)
texCoord (TexCoord2 1 (1::GLfloat))
vertex (Vertex3 1 1 (-1::GLfloat)) -- top right of quad (Right)
texCoord (TexCoord2 0 (1::GLfloat))
vertex (Vertex3 1 1 (1::GLfloat)) -- top left of quad (Right)
texCoord (TexCoord2 0 (0::GLfloat))
vertex (Vertex3 1 (-1) (1::GLfloat)) -- bottom left of quad (Right)
-- now the left
texCoord (TexCoord2 0 (0::GLfloat))
vertex (Vertex3 (-1) (-1) (-1::GLfloat)) -- bottom left of quad (Left)
texCoord (TexCoord2 1 (0::GLfloat))
vertex (Vertex3 (-1) 1 (-1::GLfloat)) -- top left of quad (Left)
texCoord (TexCoord2 1 (1::GLfloat))
vertex (Vertex3 (-1) 1 (1::GLfloat)) -- top right of quad (Left)
texCoord (TexCoord2 0 (1::GLfloat))
vertex (Vertex3 (-1) (-1) (1::GLfloat)) -- bottom right of quad (Left)
xrot $= xr + 0.3
yrot $= yr + 0.2
zrot $= zr + 0.4
-- since this is double buffered, swap the buffers to display what was just
-- drawn
flush
swapBuffers
keyPressed :: KeyboardMouseCallback
-- 27 is ESCAPE
keyPressed (Char '\27') Down _ _ = exitWith ExitSuccess
keyPressed _ _ _ _ = return ()
main :: IO ()
main = do
-- Initialize GLUT state - glut will take any command line arguments
-- that pertain to it or X windows -- look at its documentation at
-- http://reality.sgi.com/mjk/spec3/spec3.html
getArgsAndInitialize
-- select type of display mode:
-- Double buffer
-- RGBA color
-- Alpha components supported
-- Depth buffer
initialDisplayMode $= [ DoubleBuffered, RGBAMode, WithDepthBuffer,
WithAlphaComponent ]
-- get an 800 x 600 window
initialWindowSize $= Size 800 600
-- window starts at upper left corner of the screen
initialWindowPosition $= Position 0 0
-- open a window
createWindow "Jeff Molofee's GL Code Tutorial ... NeHe '99"
-- register the function to do all our OpenGL drawing
xrot <- newIORef 0
yrot <- newIORef 0
zrot <- newIORef 0
-- initialize our window.
tex <- initGL
displayCallback $= (drawScene tex xrot yrot zrot)
-- go fullscreen. This is as soon as possible.
fullScreen
-- even if there are no events, redraw our gl scene
idleCallback $= Just (drawScene tex xrot yrot zrot)
-- register the funciton called when our window is resized
reshapeCallback $= Just resizeScene
-- register the function called when the keyboard is pressed.
keyboardMouseCallback $= Just keyPressed
-- start event processing engine
mainLoop