On Friday 16 February 2007 19:35, h. wrote:
[...] and the problem: The ColorBuffer is not cleared, the window shows what was there before it was created. [...]
Just a small addition: As was already pointed out, rendering in OpenGL is not synchronous, which is a very good design decision given the capabilities and architectures of today's graphic cards. If you use single-buffering (as in your example), a 'flush' or 'finish' is needed, see: http://www.haskell.org/ghc/docs/latest/html/libraries/OpenGL/Graphics-Render... If double-buffering is used, GLUT's 'swapBuffers' is your friend: http://www.haskell.org/ghc/docs/latest/html/libraries/GLUT/Graphics-UI-GLUT-... Example: -------------------------------------------------------------------------- import Graphics.UI.GLUT main :: IO () main = do _ <- getArgsAndInitialize initialDisplayMode $= [ DoubleBuffered ] createWindow "Hello World" displayCallback $= do clear [ ColorBuffer ]; swapBuffers mainLoop -------------------------------------------------------------------------- Other UI toolkits with an OpenGL canvas will have something similar to 'swapBuffers', e.g. 'glDrawableSwapBuffers' in Gtk2Hs, IIRC. Cheers, S.