sample_l (sm4 - asm)
Samples data from the specified Element/texture using the specified address and the filtering mode identified by the given sampler.
| sample_l[_aoffimmi(u,v,w)] dest[.mask], srcAddress[.swizzle], srcResource[.swizzle], srcSampler, srcLOD.select_component |
|---|
| Item | Description |
|---|---|
| dest |
[in] The address of the results of the operation. |
| srcAddress |
[in] A set of texture coordinates. For more information see the sample instruction. |
| srcResource |
[in] A texture register. For more information see the sample instruction. |
| srcSampler |
[in] A sampler register. For more information see the sample instruction. |
| srcLOD |
[in] The LOD. |
Remarks
This instruction is identical to sample, except that LOD is provided directly by the application as a scalar value, representing no anisotropy. This instruction is available in all progammable Shader stages.
sample_l samples the texture using srcLOD to be the LOD. If the LOD value is <= 0, the zero'th (biggest map) is chosen, with the magnify filter applied (if applicable based on the filter mode). Because srcLOD is a floating point value, the fractional value is used to interpolate between two mip levels, if the minify filter is LINEAR or with anisotropic filtering.
sample_l ignores address derivatives, so filtering behavior is purely isotropic. Because derivatives are ignored, anisotropic filtering behaves as isotropic filtering.
Sampler states MIPLODBIAS and MAX/MINMIPLEVEL are honored.
When used in the Pixel Shader, sample_l implies that the choice of LOD is per-pixel, with no effect from neighboring pixels, for example in the same 2x2 stamp.
Fetching from an input slot that has nothing bound to it returns 0 for all components.
This instruction applies to the following shader stages:
| Vertex Shader | Geometry Shader | Pixel Shader |
|---|---|---|
| X | X | 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 |