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subgroup quad
A subgroup operation restricted to a 2x2 block of neighbouring pixels.
When a GPU shades pixels, it processes them in 2x2 quads so it can compare adjacent pixels — for example to estimate how fast a texture coordinate changes. Quad subgroup operations let the four threads in that block exchange values directly. This is how shaders compute derivatives and pick texture detail levels.
See also
- subgroupA small hardware bundle of shader threads on a GPU that all run in lockstep together.
- texture samplingReading a smoothly-interpolated colour from a texture image inside a shader.
- texel / texelFetchA texel is one pixel of a texture; texelFetch grabs exactly that pixel with no smoothing.