Performance of Scanline-Oriented CSG Direct Display Algorithms

摘要

CSG (Constructive Solid Geometry) direct display algorithms display a CSG modelwithout first converting the model into a boundary representation. Three such algorithms are described. All three are based on the scanline display algorithm, and are able to handle both polygonal and quadratic faces. The first algorithm is a recursive subdivision scanline algorithm, the second a combination of a scanline and a ray casting algorithm, and the third a scanline-based version of a depth-buffer algorithm. A multiprocessor system in which these algorithms can be incorporated is also described. The performances of the algorithms are compared. It turns out that the algorithms are efficient display algorithms for general-purpose architectures. Also a comparison is made between the performances for polygonal models and quadratic models, to get an indication of how many polygons can at most be used to approximate quadratic surface and still have better performance. Finally some speculations are made on future performances of CSG direct display algorithms. (Copyright (c) 1993 by Faculty of Technical Mathematics and Informatics, Delft, The Netherlands.)