Gooch shading

An example of gooch shading on the Stanford bunny
graphics complex of a seashell with gooch shading modeled in Mathematica 13.1
graphics complex of a seashell with gooch shading modeled in Mathematica 13.1

Gooch shading is a non-photorealistic rendering technique for shading objects. It is also known as "cool to warm" shading, and is widely used in technical illustration.