FAST DISPLAY OF WELL-TESSELATED SURFACES

Well-tesselated surfaces are piecewise planar functions on the sphere. Their planar faces are triangles which must meet a local geometric constraint. The faces may have arbitrary properties of transparency or reflectivity. These surfaces admit of simple hidden-line and -surface algorithms. In a raster graphics environment, the algorithms yield a priority ordering for painting entire faces. This order depends only upon the 3-D directions of face vertices as seen from the origin, and is independent of the radial position of vertices. Hence the order is independent of the actual function realized by the surface. Since perspective distortion and an approximate version of object rotation may both be accomplished by changing only radial vertex positions, these useful transformations may be visualized without resorting. Specific methods for creating well-tesselated surfaces are given, and general constraints defining them are stated. An efficient hidden surface/line algorithm is presented, with a simpler method for the case of opaque faced polyhedra. Proofs of correctness are provided. © 1979.