A graphics system based on quadrics

Abstract

Today, hardware graphics systems use three and four-sided polygons as display primitives. Polygons are very easy to scan-convert and have largely influenced software and hardware developments. Yet, as triangles have well-known limitations, the purpose of this paper is to explore a new way of displaying scenes in real-time with other primitives: quadrics. Quadrics are usually used in CSG as natural quadrics. Moreover, recent works on low degree algebraic surfaces use them as quadric patches. After having presented the modeling aspects, we define a new basic object made of one quadric and planes. The main advantage of this object is genericity, i.e., it includes polygons, natural quadrics, quadric patches, and polyhedra. Specific computations and algorithms are necessary to scan-convert our basic object. They are described precisely, with hardware constraints in mind. Finally, a processor is proposed and its cost is estimated. So, we conclude that the processor is one step toward the design of a complete graphics system based on quadrics.