textureGatherOffset(3) gathers four texels from a texture with offset

DECLARATION

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

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

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_j1(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

 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
textureGatherOffset - - - - - - ✔ ✔ ✔ ✔ ✔ ✔

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. m[blue]http://opencontent.org/openpub/m[].

COPYRIGHT


Copyright © 2011-2014 Khronos Group

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