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{-
Hello.hs (adapted from hello.c which is (c) Silicon Graphics, Inc.)
Copyright (c) Sven Panne 2002-2004 <sven.panne@aedion.de>
This file is part of HOpenGL and distributed under a BSD-style license
See the file libraries/GLUT/LICENSE
This is a simple, introductory OpenGL program.
-}
import Graphics.UI.GLUT
display :: DisplayCallback
display = do
-- clear all pixels
clear [ ColorBuffer ]
-- draw white polygon (rectangle) with corners at
-- (0.25, 0.25, 0.0) and (0.75, 0.75, 0.0)
color (Color3 1.0 1.0 (1.0 :: GLfloat))
-- resolve overloading, not needed in "real" programs
let vertex3f = vertex :: Vertex3 GLfloat -> IO ()
renderPrimitive Polygon $ mapM_ vertex3f [
Vertex3 0.25 0.25 0.0,
Vertex3 0.75 0.25 0.0,
Vertex3 0.75 0.75 0.0,
Vertex3 0.25 0.75 0.0]
-- don't wait!
-- start processing buffered OpenGL routines
flush
myInit :: IO ()
myInit = do
-- select clearing color
clearColor $= Color4 0 0 0 0
-- initialize viewing values
matrixMode $= Projection
loadIdentity
ortho 0 1 0 1 (-1) 1
-- Declare initial window size, position, and display mode (single buffer and
-- RGBA). Open window with "hello" in its title bar. Call initialization
-- routines. Register callback function to display graphics. Enter main loop and
-- process events.
main :: IO ()
main = do
getArgsAndInitialize
initialDisplayMode $= [ SingleBuffered, RGBMode ]
initialWindowSize $= Size 250 250
initialWindowPosition $= Position 100 100
createWindow "hello"
myInit
displayCallback $= display
mainLoop
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