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{-
AARGB.hs (adapted from aargb.c which is (c) Silicon Graphics, Inc.)
Copyright (c) Sven Panne 2002-2006 <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 shows how to draw anti-aliased lines. It draws two
diagonal lines to form an X; when 'r' is typed in the window, the lines are
rotated in opposite directions.
-}
import Data.Char ( toLower )
import Data.IORef ( IORef, newIORef )
import System.Exit ( exitWith, ExitCode(ExitSuccess) )
import Graphics.UI.GLUT
data State = State { rotAngle :: IORef Int }
makeState :: IO State
makeState = do
r <- newIORef 0
return $ State { rotAngle = r }
-- Initialize antialiasing for RGBA mode, including alpha blending, hint, and
-- line width. Print out implementation specific info on line width granularity
-- and width.
myInit :: IO ()
myInit = do
g <- get smoothLineWidthGranularity
putStrLn ("smoothLineWidthGranularity is " ++ show g)
r <- get smoothLineWidthRange
putStrLn ("smoothLineWidthRange is " ++ show r)
lineSmooth $= Enabled
blend $= Enabled
blendFunc $= (SrcAlpha, OneMinusSrcAlpha)
hint LineSmooth $= DontCare
lineWidth $= 1.5
clearColor $= Color4 0 0 0 0
-- Draw 2 diagonal lines to form an X
display :: State -> DisplayCallback
display state = do
r <- get (rotAngle state)
clear [ ColorBuffer ]
-- resolve overloading, not needed in "real" programs
let color3f = color :: Color3 GLfloat -> IO ()
vertex2f = vertex :: Vertex2 GLfloat -> IO ()
color3f (Color3 0 1 0)
preservingMatrix $ do
rotate (-(fromIntegral r :: GLfloat)) (Vector3 0 0 0.1)
renderPrimitive Lines $ do
vertex2f (Vertex2 (-0.5) 0.5)
vertex2f (Vertex2 0.5 (-0.5))
color3f (Color3 0 0 1)
preservingMatrix $ do
rotate (fromIntegral r :: GLfloat) (Vector3 0 0 0.1)
renderPrimitive Lines $ do
vertex2f (Vertex2 0.5 0.5)
vertex2f (Vertex2 (-0.5) (-0.5))
flush
reshape :: ReshapeCallback
reshape size@(Size w h) = do
viewport $= (Position 0 0, size)
matrixMode $= Projection
loadIdentity
let wf = fromIntegral w
hf = fromIntegral h
if w <= h
then ortho2D (-1) 1 (-1*hf/wf) (1*hf/wf)
else ortho2D (-1*wf/hf) (1*wf/hf) (-1) 1
matrixMode $= Modelview 0
loadIdentity
keyboard :: State -> KeyboardMouseCallback
keyboard state (Char c) Down _ _ = case toLower c of
'r' -> do rotAngle state $~ ((`mod` 360) . (+ 30)); postRedisplay Nothing
'\27' -> exitWith ExitSuccess
_ -> return ()
keyboard _ _ _ _ _ = return ()
-- Main Loop
-- Open window with initial window size, title bar,
-- RGBA display mode, and handle input events.
main :: IO ()
main = do
(progName, _args) <- getArgsAndInitialize
initialDisplayMode $= [ SingleBuffered, RGBMode ]
initialWindowSize $= Size 200 200
createWindow progName
state <- makeState
myInit
reshapeCallback $= Just reshape
keyboardMouseCallback $= Just (keyboard state)
displayCallback $= display state
mainLoop
|
