Direct3D9的扩展纹理格式

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在WinXP下，即使GPU支持D3D10+，也只能用D3D9的API。但实际上各个厂商都对D3D9做了一些扩展，把部分D3D10+的特性暴 露给了D3D9 API。以下是一些特殊的纹理格式，通过FOURCC的方式来使用。通过CheckDeviceFormat可以检测是否支持该格式，在 CreateTexture的时候传入即可。下表的源头是各厂商的GPU文档，经过Unity的Aras整理而来：

Usage列：DS=DepthStencil，RT=RenderTarget；Resource列：tex=texture，surf=surface。越绿表示越多硬件支持。

Format	Usage	Resource	Description	NVIDIA GeForce	ATI Radeon	Intel
Shadow mapping
D3DFMT_D16	DS	tex	Sample depth buffer directly as shadow map.	3+	HD 2xxx+	965+
D3DFMT_D24X8	DS	tex		3+	HD 2xxx+	965+
Depth Buffer As Texture
DF16	DS	tex	Read depth buffer as texture.		9500+	G45+
DF24	DS	tex			X1300+
INTZ	DS	tex		8+	HD 4xxx+	G45+
RAWZ	DS	tex		6 & 7
Anti-Aliasing related
RESZ	RT	surf	Resolve MSAA’d depth stencil surface into non-MSAA’d depth texture.		HD 4xxx+	G45+
ATOC	0	surf	Transparency anti-aliasing.	7+
SSAA	0	surf		7+
All ATI SM2.0+ hardware					9500+
n/a			Coverage Sampled Anti-Aliasing	8+
Texturing
ATI1	0	tex	ATI1n & ATI2n texture compression formats.	8+	X1300+	G45+
ATI2	0	tex		6+	9500+	G45+
DF24	DS	tex	Fetch 4: when sampling 1 channel texture, return four touched texel values. Check for DF24 support.		X1300+
Misc
NULL	RT	surf	Dummy render target surface that does not consume video memory.	6+	HD 4xxx+
NVDB	0	surf	Depth Bounds Test.	6+
R2VB	0	surf	Render into vertex buffer.	6 & 7	9500+
INST	0	surf	Geometry Instancing on pre-SM3.0 hardware.		9500+

完整的GPU扩展功能，请看：

• NVIDIA GPU Programming Guide
• Advanced DX9 Capabilities for ATI Radeon Cards – whitepaper (July 2009)