SIMD processors have become popular architectures for multimedia. Though most of the 3D graphics pipeline can be implemented on such SIMD platforms in a straightforward manner, polygon clipping tends to cause clumsy and expensive interruptions to the SIMD pipeline. This paper describes a way to increase the efficiency of SIMD clipping without sacrificing the efficient flow of a SIMD graphics pipeline. In order to fully utilize the parallel execution units, we have developed two methods to avoid serialization of the execution stream: deferred clipping postpones polygon clipping and uses hardware assistance to buffer polygons that need to be clipped. SIMD clipping partitions the actual polygon clipping procedure between the SIMD engine and a conventional RISC processor. To increase the efficiency of SIMD clipping, we introduce the concepts of clip-plane pairs and edge batching. Clip-plane pairs allow clipping a polygon against two clip planes without introducing corner vertices. Edge batching reduces the communication and control overhead for starting of clipping on the SIMD engine.

To reduce the cost of correcting design errors, assemblies of mechanical parts are modeled using CAD systems and verified electronically before the designs are sent to manufacturing.Shaded images are insufficient for examining the internal structures of assemblies and for detecting interferences.Thus, designers must rely on expensive numerical techniques that compute geometric representations of cross-sections and of intersections of solids.The solid-clipping approach presented here bypasses these geometric calculations and offers realtime rendering of cross-sections and interferences for solids represented by their facetted boundaries.In its simplest form, the technique is supported by contemporary highend graphics workstations.Its variations, independently developed elsewhere, have already been demonstrated.Our implementation is based on the concept of a cutvolume interactively manipulated to remove obstructing portions of the assembly and reveal its internal structure.For clarity, faces of the cut-volume which intersect a single solid are hatched and shaded with the color of that solid.Interference areas between two or more solids are highlighted.Furthermore, to help users find the first occurrence of an interference along a search direction, we have developed an adaptive subdivision search based on a projective approach which guarantees a sufficient condition for object disjointness.The additional performance cost for solid-clipping and interference highlighting is comparable to the standard rendering cost.An efficient implementation of the disjointness test requires a minor extension of the graphics functions currently supported on commercial hardware.

Abstract An object oriented approach to the real‐time rendering of raster images is described. The architecture is based on a set of object processors arranged in a pipeline. These object processors scan convert the objects in the scene and interpolate depth and normal vectors across the objects. Hidden surface elimination is distributed along the pipeline. The structure of the object processors and of the algorithms employed are described in detail. Computing Reviews Classification: C. 1.2, C.3, 1.3.1