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The sections in this article are 1 History 2 Basic Raster Graphics Architecture 3 Parallel Raster Graphics Architectures 4 Special Purpose Raster Graphics Architectures Keywords: graphics pipeline; frame buffer memories; video memory; video processor; display processor; geometry and rasterization subsystems; parallel vs. pipelined subsystems; object and image parallelism; special-purpose architectures

Brush provides an interactive environment for the real-time visualization and inspection of very large mechanical and architectural CAD databases. It supports immersive and non-immersive virtual reality walkthrough applications (for example, when validating or demonstrating to a customer an architectural concept) and detailed design reviews of complex mechanical assemblies such as engines, plants, airplanes, or ships.

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.