textureGather - gathers four texels from a texture

       Copyright © 2011-2014 Khronos Group

[FIXME: source]                                    11/18/2024                                  TEXTUREGATHER(3G)

gvec4textureGather(gsampler2Dsampler,vec2P,[intcomp]);gvec4textureGather(gsampler2DArraysampler,vec3P,[intcomp]);gvec4textureGather(gsamplerCubesampler,vec3P,[intcomp]);gvec4textureGather(gsamplerCubeArraysampler,vec4P,[intcomp]);gvec4textureGather(gsampler2DRectsampler,vec3P,[intcomp]);vec4textureGather(gsampler2DShadowsampler,vec2P,floatrefZ);vec4textureGather(gsampler2DArrayShadowsampler,vec3P,floatrefZ);vec4textureGather(gsamplerCubeShadowsampler,vec3P,floatrefZ);vec4textureGather(gsamplerCubeArrayShadowsampler,vec4P,floatrefZ);vec4textureGather(gsampler2DRectShadowsampler,vec3P,floatrefZ);

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.

       textureGather - gathers four texels from a texture

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.

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

       ┌───────────────┬───────────────────────────────────────────────────────────────────────────────────┐
       │               │        OpenGLShadingLanguageVersion                                            │
       ├───────────────┼──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┬──────┤
       │ Function      │ 1.10 │ 1.20 │ 1.30 │ 1.40 │ 1.50 │ 3.30 │ 4.00 │ 4.10 │ 4.20 │ 4.30 │ 4.40 │ 4.50 │
       │ Name          │      │      │      │      │      │      │      │      │      │      │      │      │
       ├───────────────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┼──────┤
       │ textureGather │  -   │  -   │  -   │  -   │  -   │  -   │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │  ✔   │
       └───────────────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┴──────┘