Off-screen rendering in Qt + OpenGL

Does anyone know if it is possible to do offscreen rendering using OpenGL as implemented in the Qt toolkit? And if so, how?

I’m using Windows XP and Qt 3.3.4

Thx in advance!

That depends on if your OpenGL driver support it, on windows you can render to an of screen buffer with the correct context setup, but this is pretty slow and only works on windows, otherwise the best choice would be to use pbuffers, then you can used the off screen buffer anyway you want.

Tack så mycket for the quick reply!

It seems my graphics card & driver has pbuffers, because a sample program using them from the nVidia site works.
But how can I check in my code if a client system also has them? In which DLL / extension / subsystem are they defined, starting with which version?

If it is available on your hardware, use FBO instead of oldskool platform-dependant pbuffer :

Thanks, ZBuffeR. Didn’t know pbuffers were older and platform-dependent. I tried FBO, and first needed to update my nVidia driver, but now the example prog works!