Nebulaud shading

Nebulaud shading is a shading model developed for real time 3D graphics in the PC demo scene. It is based on the Gouraud shading method with an additional twist. While Gouraud is a linear interpolation across the surface of a polygon, Nebulaud takes the luminosity of each pixel derived from Gouraud and shifts it within a finite field of predermined length. Ultimately this has the effect of dithering the polygon's surface which was of particular use when colorspace and CPU time were at a premium.