mirror of
https://github.com/patriciogonzalezvivo/thebookofshaders
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25 lines
1.2 KiB
Markdown
25 lines
1.2 KiB
Markdown
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## Texture2D
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Retrieves texels from a texture
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### Declaration
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```glsl
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vec4 texture2D(sampler2D sampler, vec2 coord)
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vec4 texture2D(sampler2D sampler, vec2 coord, float bias)
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```
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### Parameters
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```sampler``` specifies the sampler to which the texture from which texels will be retrieved is bound.
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```coord``` specifies the texture coordinates at which texture will be sampled.
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```bias``` specifies an optional bias to be applied during level-of-detail computation.
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### Description
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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.
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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.
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Side note: On iOS devices texture lookup functionality is only available in the fragment shader.
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### See Also
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[textureCube](index.html#textureCube.md)
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