Texture2D::GatherAlpha(S,float,int2,int2,int2,int2,uint) function

Returns the alpha components of the four texel values that would be used in a bi-linear filtering operation, along with tile-mapping status.

Syntax

TemplateType GatherAlpha(
  in  SamplerState S,
  in  float2       Location,
  in  int2         Offset1,
  in  int2         Offset2,
  in  int2         Offset3,
  in  int2         Offset4,
  out uint         Status
);

Parameters

S [in]

Type: SamplerState

The zero-based sampler index.

Location [in]

Type: float

The sample coordinates (u,v).

Offset1 [in]

Type: int2

The first offset component applied to the texture coordinates before sampling.

Offset2 [in]

Type: int2

The second offset component applied to the texture coordinates before sampling.

Offset3 [in]

Type: int2

The third offset component applied to the texture coordinates before sampling.

Offset4 [in]

Type: int2

The fourth offset component applied to the texture coordinates before sampling.

Status [out]

Type: uint

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

Type: TemplateType

A four-component value whose type is the same as the template type.

Remarks

The texture samples can be used for bilinear interpolation.

This function is supported for the following types of shaders:

See also

GatherAlpha methods