nggalai
2003-03-05, 11:40:38
Hola,
sehr interessante Statements, und nicht allzuviel PR drin. Aber lustiges spin-doctoring, IMO. ;)
Link: http://www.beyond3d.com/previews/nvidia/gffxu/index.php?p=24
Auszug:During the Dusk-Till-Dawn event and from subsequent discussions I've had with developers, there appears to be some confusion as to the status of FP32 in the DirectX drivers. Is it not the case that texture addressing needs to at least take place at FP24 (meaning FP32 for NV30) precision to meet DirectX9 compliancy? Would your drivers fail WHQL certification if there were not running at this precision of this stage of the shader pipe?
According to DirectX 9 spec, FP24 is allowed, but we at NVIDIA believe it is insufficient to avoid errors for a variety of texture and geometry calculations. So we designed our products to use FP32. For example, NVIDIA uses FP32 for texture address calculation. In the case of dependent texture reads (e.g. a bumpy shiny object with a reflection map in a scene), full precision (FP32) for the texture address calculation is critical for getting a high-quality result.
It is unfortunate that the spec is lax on this point because FP32 is also important to match the FP precision for any work that is done on the CPU (whether Pentium4 or Athlon). Some applications still do load balancing by performing some geometry processing on the CPU. If some math is done in FP32 on the CPU (CPUs don't recognize the FP24 format) and other math is done at FP24 on the GPU, you will get errors. Because pixel shading units are now capable of rendering geometry, they need to have the same precision as the vertex shading unit. Advanced pixel shading programs can render data to a texture that is subsequently read back into the Vertex Shading Engine for additional geometric processing. For this reason, it is much better to have the same precision through the entire process.
And, of course, drivers would fail WHQL if they fail to meet minimum WHQL requirements such as FP24 or higher for texture address calculation.
93,
-Sascha.rb
sehr interessante Statements, und nicht allzuviel PR drin. Aber lustiges spin-doctoring, IMO. ;)
Link: http://www.beyond3d.com/previews/nvidia/gffxu/index.php?p=24
Auszug:During the Dusk-Till-Dawn event and from subsequent discussions I've had with developers, there appears to be some confusion as to the status of FP32 in the DirectX drivers. Is it not the case that texture addressing needs to at least take place at FP24 (meaning FP32 for NV30) precision to meet DirectX9 compliancy? Would your drivers fail WHQL certification if there were not running at this precision of this stage of the shader pipe?
According to DirectX 9 spec, FP24 is allowed, but we at NVIDIA believe it is insufficient to avoid errors for a variety of texture and geometry calculations. So we designed our products to use FP32. For example, NVIDIA uses FP32 for texture address calculation. In the case of dependent texture reads (e.g. a bumpy shiny object with a reflection map in a scene), full precision (FP32) for the texture address calculation is critical for getting a high-quality result.
It is unfortunate that the spec is lax on this point because FP32 is also important to match the FP precision for any work that is done on the CPU (whether Pentium4 or Athlon). Some applications still do load balancing by performing some geometry processing on the CPU. If some math is done in FP32 on the CPU (CPUs don't recognize the FP24 format) and other math is done at FP24 on the GPU, you will get errors. Because pixel shading units are now capable of rendering geometry, they need to have the same precision as the vertex shading unit. Advanced pixel shading programs can render data to a texture that is subsequently read back into the Vertex Shading Engine for additional geometric processing. For this reason, it is much better to have the same precision through the entire process.
And, of course, drivers would fail WHQL if they fail to meet minimum WHQL requirements such as FP24 or higher for texture address calculation.
93,
-Sascha.rb