On 14/10/2007, Chris Robinson chris.kcat@gmail.com wrote:
On Sunday 14 October 2007 02:57:35 am H. Verbeet wrote:
Unless the performance problems with R32F have been fixed, this will cause performance regressions in applications that actually try to use it. (C&C3 for example).
Thinking some more, it's also possible that wined3d's too lax in reporting 32-bit float formats. GL's float extension requires both 32-bit and 16-bit formats (the half-float extension is only for uploading 16-bit float data) with all the blending effects. By contrast, D3D drivers may have supported 16-bit floats first, and not reported 32-bit floats until the hardware was powerful enough.
Perhaps if 32-bit float formats aren't reported unless some other cap indicates newer hardware is present, it'll prevent apps from using 32-bit floats where it'd be a detriment to speed.
IIRC it's specifically R32F that's slow, while A32B32G32R32F should work ok. Looking at the format table, perhaps that's just GL_RGB32F_ARB vs GL_RGBA32F_ARB, not sure. If nobody else does, I can try to look into that tomorrow.