I've been trying to catch up what hacks GPU vendors have exposed in Direct3D9, and turns out there's a lot of them!
If you know more hacks or more details, please let me know! (mail or comment on my blog post).
Most hacks are exposed as custom ("FOURCC") formats. So to check for
that, you do CheckDeviceFormat. Here's the list (Usage column codes: DS=DepthStencil,
RT=RenderTarget; Resource column codes: tex=texture, surf=surface). More green = more hardware support.
| 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+ | ||
| DF24 | DS | tex | X1300+ | |||
| INTZ | DS | tex | 8+ | HD 4xxx+ | ||
| 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+ | ||
| ATOC | 0 | surf | Transparency anti-aliasing. | 7+ | ||
| SSAA | 0 | surf | 7+ | |||
| All ATI SM2.0+ hardware | 9500+ | |||||
| n/a | Coverage Sampled Anti-Aliasing[6] | 8+ | ||||
| Texturing | ||||||
| ATI1 | 0 | tex | ATI1n & ATI2n texture compression formats. | 8+ | X1300+ | |
| ATI2 | 0 | tex | 6+ | 9500+ | ||
| DF24 | DS | tex | Fetch 4: when sampling 1 channel texture, return four touched texel values[1]. 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+ | ||
Native support for shadow map sampling & filtering was introduced ages ago by NVIDIA. Turns out ATI also implemented the same feature for it's DX10 level cards. Yay!
Intel note: Intel 965 (aka GMA X3100, the shader model 3 card) and G45 (aka GMA X4500; the shader model 4 card) report that D16 & D24X8 are supported for shadow mapping. Haven't checked whether it actually works. Earlier GPU (945 aka GMA 950; the shader model 2 card) does not support any of the above D3D9 hacks.
The usage is quite simple; just create a texture with regular depth/stencil format and render into it. When reading from the texture, one extra component in texture coordiantes will be the depth to compare with. Compared & filtered result will be returned.
Also useful:
For some rendering schemes (anything with "deferred") or some effects (SSAO, depth of field, volumetric fog, ...) having access to a depth buffer is needed. If native depth buffer can be read as a texture, this saves both memory and a rendering pass or extra output for MRTs.
Depending on hardware, this can be achieved via INTZ, RAWZ, DF16 or DF24 formats:
Direct equivalent of GL_EXT_depth_bounds_test OpenGL extension. See [3] for more information.
NVIDIA exposes two controls: transparency multisampling (ATOC) and transparency supersampling (SSAA) [5]. ATI says that all Radeons since 9500 support "alpha to coverage" [1].
Similar to "stream out" or "memexport" in other APIs/platforms. See [2] for more information. Apparently some NVIDIA GPUs (or drivers?) support this as well.
Instancing is supported on all Shader Model 3.0 hardware by Direct3D 9.0c, so there's no extra hacks necessary there. ATI has exposed a capability to enable instancing on their Shader Model 2.0 hardware as well. Check for "INST" support, and do dev->SetRenderState (D3DRS_POINTSIZE, kFourccINST); at startup to enable instancing.
I can't find any document on instancing from AMD now. Other references: [7] and [8].
All this information gathered mostly from: