Ah, that's good to know. I thought initGL would create the context. Sorry to be unclear in the code I posted, but part of createGUIObject is a glDrawingAreaNew. It creates a drawing area, which is then stored in a giant UserInterface record. data UserInterface = MainWindow { ... , drawing_canvas :: GLDrawingArea } createGUIObject = do ... config <- glConfigNew ... canvas <- glDrawingAreaNew config return $ MainWindow { ... drawing_canvas = canvas .. } It seems that won't create the context? do I have to show the window first, or can I just do... withGLDrawingArea $ glGenObjects n ? Thanks! -- Jeff On Thu, Nov 6, 2008 at 9:15 PM, Bertram Felgenhauer wrote:

[CCing gtk2hs-users]

Jefferson Heard wrote:

...

import Graphics.UI.Gtk import Graphics.UI.Gtk.Glade import Graphics.UI.Gtk.OpenGL import qualified Graphics.Rendering.OpenGL as GL import Graphics.Rendering.OpenGL (($=))

main = do initGUI initGL

"initGL" may be slightly misleading - it initialises the gtkglext gtk+ extension. It does not create a GL context.

...

GL.shadeModel $= GL.Flat GL.depthFunc $= Just GL.Less (window1,gui,dlgs) <- constructGUIObject (sX, sY) <- liftM (mapPair fromIntegral) . widgetGetSize . drawing_canvas $ gui -- get the canvas size for determining the part of the widget to repaint pb <- pixbufNew ColorspaceRgb False 8 (round pbWidth) (round pbHeight) pixbufFill pb 0 0 0 255 pxbufs <- initSubpixbufs pb texRows texCols textures <- GL.genObjectNames (texRows*texCols) print textures

There is no active GL context at this point. GtkGLExt creates new GL contexts for GL enabled widgets when they're realized - I think. I'm a bit fuzzy about the exact life time of the GL context. [1]

After the context was created, you have to activate it before doing any GL operations.

In Gtk2hs you can use the GLDrawingArea widget, which provides withGLDrawingArea for easy activation of the GL context.

There's an example in the gtk2hs sources, in examples/opengl.

Enabling GL for other widgets is not supported well at the moment. (There are low level bindings (using DrawWindow), but no generic binding to the higher level gtk_widget_set_gl_capability() call. Such support wouldn't be too hard to add, I think.)

HTH,

Bertram

[1] see http://gtkglext.sourceforge.net/reference/gtkglext/gtkglext-gtkglwidget.html...

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