A novel highlight shader depicts cartoon-style highlights for 3D objects in cel animation. In general, highlighting in cel animation is used semantically, rather than photorealistically, by employing simple primitives-such as white stripes on a window or crescent figures on an alloy wheel. It's difficult and tedious work, however, to get such a stylized highlight animation for 3D models when using conventional cartoon-shading algorithms.This article presents an approach that generalizes the concept of a highlight for 3D objects in cel animation. This is achieved by introducing a new class of vector field-called a highlight vector field-on a surface to be depicted. A generalized highlight area on the surface is then defined through the highlight vector field. Thus, this highlight shader enables cartoon-style highlighting through simple operations defined for the highlight vector field. These operations actually correspond to the direct manipulations on the highlight area defined by the vector field, these include local affine transform and simple deformation of the highlight.
“Stylized Highlights for Cartoon Rendering and Animation”,
IEEE Computer Graphics and Applications Vol.23 No. 4 (Special issue on Non-Photorealistic Rendering, July/August 2003) pp.54-61