CSG Scanline Algorithm for Quadrics

摘要

CSG (Constructive Solid Geometry) is a method for defining complex solid objectsas a combination of simple primitives. An efficient scanline display algorithm for CSG models with quadric primitives is presented. Efficiency is gained by making use of silhouette curves, and by splitting the scanline sections into monotonic pieces, which allows efficient testing for interactions on spans and avoids the calculation of depth values of the faces at every pixel. A procedure for the selective skipping of spans, which in complex cases leads to a substantial reduction of the number of spans to be processed and gives an increase of the average length of the spans, is given.