I filed a bug report a long while ago, about Doom 3 BFG not working on WinXP. It was never answered, but that no longer matters since WinXP is now obsolete. I am hoping that AMD still supports OpenGL and is interested in fixing the driver so that indie devs who use open source engine from iD Software would deliver games to AMD users too, not only to Nvidia and Intel users.
We are using modified Doom 3 BFG engine (id Tech 4 with threading and renderer from id Tech 5) to power our upcoming game. Currently the engine works like a clock using Nvidia and Intel GPUs, but has severe performance issues on AMD.
Particularly it runs at ~60 fps on GeForce 670 GTX installed on AMD Phenom x3 2.2Ghz under Windows 7, but on the same scene it runs at ~20fps on AMD HD7850 installed on AMD Phenom x4 2.4Ghz under Windows 8.1.
Is there any specific person I can get a hold of to discuss whether it's possible for AMD to look into the issue and resolve it (it's strange that it hasn't been resolved, since RAGE has been out for loooong time and since then none of the id Tech 5 based games perform well on AMD GPUs) or if we should give up on AMD OpenGL driver and either add DirectX renderer (which is least likely to happen) or simply not support AMD GPUs (which of course doesn't matter to AMD, but matters to us since AMD has a larger user base than Nvidia and Intel, based on Steam hardware stats) ?
Thank you for your time.