HaskellでOpenGL(GLUT)を使って、直線を描画する。

2d-line.hs

import Graphics.UI.GLUT

display :: DisplayCallback
display = do
    clear [ColorBuffer]
    color (Color3 0 0 0 :: Color3 GLdouble)
    renderPrimitive Lines $ mapM_ vertex2d [
          Vertex2 (-0.9) (-0.9)
        , Vertex2 0.9 0.9
        ]
    flush
        where
            vertex2d = vertex :: Vertex2 GLdouble -> IO ()

main :: IO ()
main = do
    getArgsAndInitialize
    initialDisplayMode $= [RGBAMode]
    createWindow "Sample"
    clearColor $= Color4 1 1 1 1
    displayCallback $= display
    mainLoop