I adapted an OpenGL pixel shaders demo using pbuffers to the ATI drivers, and to get it to work I had to stop using the “SGIX” extension (glXChooseFBConfigSGIX never returned any fb config at all?) and use the “GLX” one.
As the demo was originally written for NVidia, (http://www.frustum.org/3d/) I assume it did work on that. I’m not so sure it stil does.
What is the difference between those two extensions anyway?
Do I have to include seperate code paths for NVidia and ATI cards?
The functionality is pretty much the same. I think there was some functionality in the SGIX version that was removed for GLX 1.3. The entry points will be different, and the way you check which is available is different. If GLX 1.3 or higher is supported, use glXChooseFBConfg. If the extension “GLX_SGIX_fbconfig” is available, use glXChooseFBConfigSGIX.