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Sample(S,float,int,float,uint) function

Samples a Texture2D with an optional value to clamp sample level-of-detail (LOD) values to, and returns status of the operation.

Note  Requires shader model 5 or higher.

Syntax

DXGI_FORMAT Sample(
  in  SamplerState S,
  in  float Location,
  in  int Offset,
  in  float Clamp,
  out uint Status
);

Parameters

S [in]

A Sampler state. This is an object declared in an effect file that contains state assignments.

Location [in]

The texture coordinates. The argument type is dependent on the texture-object type.

Texture-Object TypeParameter Type
Texture1Dfloat
Texture1DArray, Texture2Dfloat2
Texture2DArray, Texture3D, TextureCubefloat3
TextureCubeArrayfloat4

 

Offset [in]

An optional texture coordinate offset, which can be used for any texture-object type; the offset is applied to the location before sampling. Use an offset only at an integer miplevel; otherwise, you may get results that do not translate well to hardware. The argument type is dependent on the texture-object type. For more info, see Applying Integer Offsets.

Texture-Object TypeParameter Type
Texture1D, Texture1DArrayint
Texture2D, Texture2DArrayint2
Texture3Dint3
TextureCube, TextureCubeArraynot supported

 

Clamp [in]

An optional value to clamp sample LOD values to. For example, if you pass 2.0f for the clamp value, you ensure that no individual sample accesses a mip level less than 2.0f.

Status [out]

The status of the operation. You can't access the status directly; instead, pass the status to the CheckAccessFullyMapped intrinsic function. CheckAccessFullyMapped returns TRUE if all values from the corresponding Sample, Gather, or Load operation accessed mapped tiles in a tiled resource. If any values were taken from an unmapped tile, CheckAccessFullyMapped returns FALSE.

Return value

The texture format, which is one of the typed values listed in DXGI_FORMAT.

Remarks

Texture sampling uses the texel position to look up a texel value. An offset can be applied to the position before lookup. The sampler state contains the sampling and filtering options. This method can be invoked within a pixel shader, but it is not supported in a vertex shader or a geometry shader.

Calculating Texel Positions

Texture coordinates are floating-point values that reference texture data, which is also known as normalized texture space. Address wrapping modes are applied in this order (texture coordinates + offsets + wrap mode) to modify texture coordinates outside the [0...1] range.

For texture arrays, an additional value in the location parameter specifies an index into a texture array. This index is treated as a scaled float value (instead of the normalized space for standard texture coordinates). The conversion to an integer index is done in the following order (float + round-to-nearest-even integer + clamp to the array range).

Applying Texture Coordinate Offsets

The offset parameter modifies the texture coordinates, in texel space. Even though texture coordinates are normalized floating-point numbers, the offset applies an integer offset.

The data format returned is determined by the texture format. For example, if the texture resource was defined with the DXGI_FORMAT_A8B8G8R8_UNORM_SRGB format, the sampling operation converts sampled texels from gamma 2.0 to 1.0, filter, and writes the result as a floating-point value in the range [0..1].

See also

Texture-Object

 

 

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