The Book of Shaders by Patricio Gonzalez Vivo


Retrieves texels from a texture


vec4 texture2D(sampler2D sampler, vec2 coord)  
vec4 texture2D(sampler2D sampler, vec2 coord, float bias)


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

coord specifies the texture coordinates at which texture will be sampled.

bias specifies an optional bias to be applied during level-of-detail computation.


The texture2D function returns a texel, i.e. the (color) value of the texture for the given coordinates. The function has one input parameter of the type sampler2D and one input parameter of the type vec2 : sampler, the uniform the texture is bound to, and coord, the 2-dimensional coordinates of the texel to look up.

There is an optional third input parameter of the type float: bias. After calculating the appropriate level of detail for a texture with mipmaps the bias is added before the actual texture lookup operation is executed.

Side note: On iOS devices texture lookup functionality is only available in the fragment shader.

See Also