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Rate of change of contents of each float32 component of src0 (post-swizzle), with regard to RenderTarget x direction (rtx) or RenderTarget y direction.
| deriv_rtx[_sat] dest[.mask], [-]src0[_abs][.swizzle], |
|---|
| Item | Description |
|---|---|
| dest |
[in] The address of the result of the operation. |
| src0 |
[in] The component in the operation. |
Remarks
Only a single x,y derivative pair is computed for each 2x2 stamp of pixels.
This operation is hardware dependent.
Reference rasterizer implementation for triangles:
- Pixel Shader always runs Shader over 2x2 quad of pixels in lockstep (even through flow control, masking disabled pixels).
- Quads always have even numbered pixel coordinates (both x and y) for top-left pixel.
- Dummy pixels run off primitive if primitive is too small to fill a 2x2 quad.
- deriv_rtx is computed by first choosing 2 pixels: the current pixel and the other pixel with the same y coordinate from the quad. Then, the result is calculated as: src0(odd x pixel) - src0(even x pixel) [per-component]
- deriv_rty is computed by first choosing 2 pixels: the current pixel and the other pixel with the same x coordinate from the quad. Then, the result is calculated as: src0(odd y pixel) - src0(even y pixel) [per-component]
This instruction applies to the following shader stages:
| Vertex Shader | Geometry Shader | Pixel Shader |
|---|---|---|
| x |
Minimum Shader Model
This function is supported in the following shader models.
| Shader Model | Supported |
|---|---|
| Shader Model 5 | yes |
| Shader Model 4.1 | yes |
| Shader Model 4 | yes |
| Shader Model 3 (DirectX HLSL) | no |
| Shader Model 2 (DirectX HLSL) | no |
| Shader Model 1 (DirectX HLSL) | no |