Polygon-to-Object Boundary Clipping in Object Space for Hidden Surface Removal in Computer-Aided Design

Abstract

Since techniques for both polygon-to-polygon clipping and polygon-to-object boundary (contour) clipping have been developed, it appears that the visibility problem may exhibit potential for improvement in its time complexity. This paper provides some insight and results concerning the performance of an object-space hidden surface removal algorithm based on polygon-to-object boundary (contour) clipping. The applicability of these results to the graphic rendering of partially visible objects in an incremental computer-aided geometric design system, such as that used in mechanical design, is demonstrated. The polygon-to-object boundary clipping algorithm is compared with the more conventional polygon-to-polygon approach to clipping for hidden surface removal. Examples are included which demonstrate the potential for improving the performance of software-based hidden surface removal algorithms used in computer-aided geometric design applications.