textureGatherOffset

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Gathers four texels from a texture with offset.

Declaration[edit]

gvec4 textureGatherOffset( gsampler2D sampler, vec2 P, ivec2 offset, [int comp] );
gvec4 textureGatherOffset( gsampler2DArray sampler, vec3 P, ivec2 offset, [int comp] );
gvec4 textureGatherOffset( gsampler2DRect sampler, vec3 P, ivec2 offset, [int comp] );
vec4 textureGatherOffset( gsampler2DShadow sampler, vec2 P, float refZ, ivec2 offset );
vec4 textureGatherOffset( gsampler2DArrayShadow sampler, vec3 P, float refZ, ivec2 offset );
vec4 textureGatherOffset( gsampler2DRectShadow sampler, vec3 P, float refZ, ivec2 offset );


Parameters[edit]

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.
offset - Specifies the offset from the specified texture coordinate P from which the texels will be gathered.


Description[edit]

 textureGatherOffset returns the value:

   vec4(Sample_i0_j1(P + offset, base).comp,
        Sample_i1_j1(P + offset, base).comp,
        Sample_i1_j0(P + offset, base).comp,
        Sample_i0_j0(P + offset, base).comp);


It perfoms as textureGather but with offset applied as described in textureOffset , except that the implementation-dependent minimum and maximum offset values are given by GL_MIN_PROGRRAM_TEXTURE_GATHER_OFFSET and GL_MAX_PROGRAM_TEXTURE_GATHER_OFFSET , respectively.

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[edit]

textureGatherOffset 4.0+

See Also[edit]

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


Copyright[edit]

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/.