Derivative Shader -

— how modern GPUs compute screen-space partial derivatives via quad rasterization.

Measures the change between the current pixel and the neighbor above or below it. derivative shader

For any developer moving beyond simple texture lookups into the realm of procedural generation or custom lighting models, mastery of ddx , ddy , and fwidth is not optional—it is mandatory. — how modern GPUs compute screen-space partial derivatives

Because derivative calculations are hardcoded into the GPU hardware (often utilizing specialized differential units), the instruction cost is negligible. In many scenarios, utilizing derivatives is faster than alternatives. mastery of ddx