View Full Version : initialization of FBO

12-29-2010, 08:16 PM
I have a scene that can be manipulated by user interaction. When there changes to the orientation, I draw the scene in an encoded fashion to an FBO, which works well.
I can't figure out how to call this encoding upon the first draw though. I don't want to call the encoding during every paint event, only those that change orientation of the scene.
I thought I could call my FBO encoder as the last call of initializeGL, but this is not working, I get an illegal framebuffer operation in this case.
1) How can I draw to an FBO as a one off upon initialization?
Of course I can make a first_pass flag in paintGL and do it from there, but it seems messy to have a statement in paintGL that is only used to call a function once.
2) Why can't I draw from the last line of initializeGL? It seems the context is valid, but something prevents the draw to the FBO from working.

Hope someone can assist!

Alfonse Reinheart
12-29-2010, 09:09 PM
It's kind of hard to know what your problem is since we don't know what "initializeGL" and "paintGL" are. We don't have your code.

12-31-2010, 06:01 AM
sorry, that was QT speak.
initializeGL is the initialization function, I would assume analogous to glutInit
paintGL is analogous to the function passed to glutDisplayFunc.
So I guess the question is whether one should be able to draw to the FBO during initialization - generally?
It may be that my problem is Qt specific if so I'll take it to the appropriate forum.