Display techniques and boundary evaluation of a Sweep-CSG modeller

Abstract

Among the various techniques for displaying solid objects, ray tracing is the most popular method for sweep-generated objects, owing to its simplicity and effectiveness. The main problem in ray tracing is to find the point of intersection between the ray and the object. By taking consideration of the special features of a surface generated by sweep, the ray/object intersection problem can be reduced to 2-D planar problem. This paper presents a raycasting technique for displaying Sweep-CSG-represented solids. This technique works directly on the Sweep-CSG representation and does not require explicit boundary information. Boundary information is, however essential for line-drawing outputs. In this paper, boundary-evaluation techniques for obtaining edges of a Sweep-CSG solid are described. Special techniques for evaluating the boundaries of a solid generated by sweeping another solid are also discussed. © 1991 Springer-Verlag.