Built-In Functions - Praise for OpenGL ES 30 Programming Guide - page 481

Table B-9 Texture Lookup Functions (continued)

Syntax Description

gvec4 textureGrad (gsampler2D sampler , vec2 P ,
vec2 dPdx , vec2 dPdy )
gvec4 textureGrad (gsampler3D sampler , vec3 P ,
vec3 dPdx , vec3 dPdy )
gvec4 textureGrad (gsamplerCube sampler , vec3 P ,
vec3 dPdx , vec3 dPdy )
float textureGrad (sampler2DShadow sampler , vec3 P ,
vec2 dPdx , vec2 dPdy )
float textureGrad (samplerCubeShadow sampler , vec4 P ,
vec3 dPdx , vec3 dPdy )
gvec4 textureGrad (gsampler2DArray sampler , vec3 P ,
vec2 dPdx , vec2 dPdy )
float textureGrad (sampler2DArrayShadow sampler , vec4 P ,
vec2 dPdx , vec2 dPdy )

Do a texture lookup as in texture but with
explicit gradients. The partial derivatives of P
are with respect to window x and window y .

gvec4 textureGradOffset (gsampler2D sampler , vec2 P ,
vec2 dPdx , vec2 dPdy , ivec2 offset )
gvec4 textureGradOffset (gsampler3D sampler , vec3 P ,
vec3 dPdx , vec3 dPdy , ivec3 offset )
float textureGradOffset (sampler2DShadow sampler , vec3 P ,
vec2 dPdx , vec2 dPdy , ivec2 offset )
gvec4 textureGradOffset (gsampler2DArray sampler , vec3 P ,
vec2 dPdx , vec2 dPdy , ivec2 offset )
float textureGradOffset (sampler2DArrayShadow sampler ,
vec4 P , vec2 dPdx , vec2 dPdy , ivec2 offset )

Do a texture lookup with both explicit
gradient and offset, as described in
textureGrad and textureOffset .