textureGather - OpenGL 4 Reference Pages

## Name

textureGather — gathers four texels from a texture

## Declaration

`gvec4 textureGather(` | gsampler2D sampler,
| vec2 P,
| [int comp]`)`;

`gvec4 textureGather(` | gsampler2DArray sampler,
| vec3 P,
| [int comp]`)`;

`gvec4 textureGather(` | gsamplerCube sampler,
| vec3 P,
| [int comp]`)`;

`gvec4 textureGather(` | gsamplerCubeArray sampler,
| vec4 P,
| [int comp]`)`;

`gvec4 textureGather(` | gsampler2DRect sampler,
| vec3 P,
| [int comp]`)`;

`vec4 textureGather(` | gsampler2DShadow sampler,
| vec2 P,
| float refZ`)`;

`vec4 textureGather(` | gsampler2DArrayShadow sampler,
| vec3 P,
| float refZ`)`;

`vec4 textureGather(` | gsamplerCubeShadow sampler,
| vec3 P,
| float refZ`)`;

`vec4 textureGather(` | gsamplerCubeArrayShadow sampler,
| vec4 P,
| float refZ`)`;

`vec4 textureGather(` | gsampler2DRectShadow sampler,
| vec3 P,
| float refZ`)`;

## Parameters

`sampler`

  Specifies the sampler to which the texture from which texels will be retrieved is bound.

`P`

  Specifies the texture coordinates at which texture will be sampled.

`comp`

  Specifies the component of the source texture that will be used to generate the resulting vector.

`refZ`

  Specifies the reference Z value used in the comparison for shadow forms.

## Description

`textureGather` returns the value:

        vec4(Sample_i0_j1(P, base).comp,
             Sample_i1_j1(P, base).comp,
             Sample_i1_j0(P, base).comp,
             Sample_i0_j1(P, base).comp);

If specified, the value of `comp` must ba constant integer expression with a value of 0, 1, 2, or 3, identifying the x, y, z or w component of the four-component vector lookup result for each texel, respectively. If `comp` is not specified, it is treated as 0, selecting the x component of each texel to generate the result.

## Version Support

| OpenGL Shading Language Version
--- | ---
Function Name | 1.10 | 1.20 | 1.30 | 1.40 | 1.50 | 3.30 | 4.00 | 4.10 | 4.20 | 4.30 | 4.40 | 4.50
textureGather | - | - | - | - | - | - | ✔ | ✔ | ✔ | ✔ | ✔ | ✔

## See Also

texelFetch, texelFetchOffset, texture, textureGatherOffset, textureGatherOffsets, textureGrad, textureGradOffset, textureLod, textureLodOffset, textureOffset, textureProj, textureProjGrad, textureProjGradOffset, textureProjLod, textureProjLodOffset, textureProjOffset, textureQueryLod, textureSize

## Copyright

Copyright © 2011-2014 Khronos Group. This material may be distributed subject to the terms and conditions set forth in the Open Publication License, v 1.0, 8 June 1999. http://opencontent.org/openpub/.