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FAQ-10 GeForce FX 系列在DirectX中支持那些浮点的帧缓存格式?
在DirectX 9.0下, 所有的 FX-系列 GPU支持的浮点帧缓存使用 "multi-element texture_多元素纹理"机制。 如同在DXSDK的文档中描述的那样,允许你同时向4个输出端输出,每个32位宽,总共128位。这其中的每一个又可以分为4x8, 2x16fp, 或 1x32fp. 为了使用这个格式的帧缓存,使用如下的标志创建它们:
NVE0: NV_SURFACE_FORMAT_IMAGE_MET_4_4_4_4
NVE1: NV_SURFACE_FORMAT_IMAGE_MET_4_4_4_2
NVE2: NV_SURFACE_FORMAT_IMAGE_MET_4_4_4_1
NVE3: NV_SURFACE_FORMAT_IMAGE_MET_4_4_2_2
NVE4: NV_SURFACE_FORMAT_IMAGE_MET_4_4_2_1
NVE5: NV_SURFACE_FORMAT_IMAGE_MET_4_4_1_1
NVE6: NV_SURFACE_FORMAT_IMAGE_MET_4_2_2_2
NVE7: NV_SURFACE_FORMAT_IMAGE_MET_4_2_2_1
NVE8: NV_SURFACE_FORMAT_IMAGE_MET_4_2_1_1
NVE9: NV_SURFACE_FORMAT_IMAGE_MET_4_1_1_1
NVEa: NV_SURFACE_FORMAT_IMAGE_MET_2_2_2_2
NVEb: NV_SURFACE_FORMAT_IMAGE_MET_2_2_2_1
NVEc: NV_SURFACE_FORMAT_IMAGE_MET_2_2_1_1
NVEd: NV_SURFACE_FORMAT_IMAGE_MET_2_1_1_1
这里, 4=4xFX8, 2=2xFP16, 1=1xFP32. 例如,NVE7 在输出端索引为0的位置,有4个8位的元素;索引为1和2的位置,有2个16位的元素;索引为3的位置,有1个32位的元素。如你所见,所有的格式具有4块,每一块的宽度是32位。
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What floating-point surface formats does the GeForce FX family support in DirectX?
Under DirectX 9.0, all all GeForce FX-class GPU's support floating point surfaces using the multi-element texture mechanism. Multi-element textures, as described in the DXSDK documentation, allows you to render to 4 simultaneous outputs, each being 32-bits wide, for a total of 128-bits. Each of these 32-bit components can be written to as 4x8, 2x16fp, or 1x32fp. To use these surfaces, create them using the following FourCC formats:
NVE0: NV_SURFACE_FORMAT_IMAGE_MET_4_4_4_4
NVE1: NV_SURFACE_FORMAT_IMAGE_MET_4_4_4_2
NVE2: NV_SURFACE_FORMAT_IMAGE_MET_4_4_4_1
NVE3: NV_SURFACE_FORMAT_IMAGE_MET_4_4_2_2
NVE4: NV_SURFACE_FORMAT_IMAGE_MET_4_4_2_1
NVE5: NV_SURFACE_FORMAT_IMAGE_MET_4_4_1_1
NVE6: NV_SURFACE_FORMAT_IMAGE_MET_4_2_2_2
NVE7: NV_SURFACE_FORMAT_IMAGE_MET_4_2_2_1
NVE8: NV_SURFACE_FORMAT_IMAGE_MET_4_2_1_1
NVE9: NV_SURFACE_FORMAT_IMAGE_MET_4_1_1_1
NVEa: NV_SURFACE_FORMAT_IMAGE_MET_2_2_2_2
NVEb: NV_SURFACE_FORMAT_IMAGE_MET_2_2_2_1
NVEc: NV_SURFACE_FORMAT_IMAGE_MET_2_2_1_1
NVEd: NV_SURFACE_FORMAT_IMAGE_MET_2_1_1_1
Here, 4=4xFX8, 2=2xFP16, and 1=1xFP32. So, for example, NVE7 has 8-bit components at element index 0, 16-bit FP at index 1 and 2, and 32-bit FP at index 3. As you can see, all formats have 4 “chunks”, and each chunk is always 32 bits. MET_1_1_1_1 is coming soon.
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