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baerentzen
02-10-2010, 03:04 AM
Dear OpenGL Coders,

I remember a few years ago gl_FragCoord did not work on AMD maybe that is still the case? I have a feeling that it could still be the case and maybe there are other gotchas.

Does anyone know of present differences between how AMD's OpenGL implementation works and the standard?

Does anyone know of present differences between how AMD's OpenGL implementation works and NVIDIA's?

I could not find anything using Google, but it seems to me that there _are_ subtle differences, and I was wondering what your experiences are?

My particular problem is that I am authoring a small volume rendering program that does not seem to work on AMD hardware, specifically ATI Mobility FireGL V5700, OpenGL version 2.1.8306. However, I am not sure where the problem is - maybe 3D textures. It works fine on my Mac/Geforce 8600M GT.

Thanks
Andreas

Pierre Boudier
02-10-2010, 05:06 AM
hi andreas,

there has been several fixes about gl_FragCoord in the amd opengl driver; please use the most recent driver and let us know if you still have any issue.

baerentzen
02-10-2010, 05:25 AM
hi andreas,

there has been several fixes about gl_FragCoord in the amd opengl driver; please use the most recent driver and let us know if you still have any issue.

Great! However, I avoided using gl_FragCoord and the problem persists. So, I was really after known issues where an OpenGL programmer porting from an NVIDIA platform might get stuck.

I am using 3D textures and that is where I mostly suspect that things go wrong.

Pierre Boudier
02-10-2010, 07:06 AM
just to clarify: the driver on mac os is owned/written by apple, so your application could behave differently on windows/linux for either nvidia/amd.
I am not aware of any issue with 3d textures, which are used quite a bit