POLYGON-TO-OBJECT BOUNDARY CLIPPING IN OBJECT SPACE FOR HIDDEN SURFACE REMOVAL IN COMPUTER-AIDED-DESIGN

Since technique for both polygon-to-polygon clipping and polygon-to-ob ject boundary (contour) clipping have been developed, it appears that the visibility problem may exhibit potential for improvement in its ti me complexity. This paper provides some insight and results concerning the performance of an object-space hidden surface removal algorithm b ased on polygon-to-object boundary (contour) clipping. The applicabili ty of these results to the graphic rendering of partially visible obje cts 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 po lygon-to-polygon approach to clipping for hidden surface removal. Exam ples are included which demonstrate the potential for improving the pe rformance of software-based hidden surface removal algorithms used in computer-aided geometric design applications.