ABSTRACT
This chapter presents a set of techniques that can be implemented using the Graphics Processing Unit by taking advantage of the geometry shader pipeline stage. It shows that how to make use of the geometry shader in order to render objects and their silhouettes in a single pass, and to imitate pencil drawing. The chapter also presents a novel approach for the detection, generation, and texturing of a model in a single rendering pass. Silhouette rendering is a fundamental element in most Non-photorrealistic rendering (NPR) effects, as it plays an important role in object shape understanding. Most silhouette rendering algorithms perform two passes, one for the geometry, and another one for the silhouettes. Once the silhouette geometry has been generated, it becomes obvious that texturing this geometry will increase the number of effects that can be achieved. Texture coordinates generation is a bit tricky, as peoples need to generate continuous coordinates along the entire silhouette.
