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    M-Buffer: A Flexible MISD Architecture for AdvancedGraphics
    (The Eurographics Association, 1992) Schneider, Bengt-Olaf; Rossignac, Jarek; P F Lister
    Contemporary graphics architectures are based on a hardware-supported geometric pipeline, a rasterizer, a z-buffer and two frame buffers. Additional pixel memory isused for alpha blending and for storing logical information. Although their functionality is growing it is still limited because of the fixed use of pixel memory and there stricted set of operations provided by these architectures. A new class of graphicsalgorithms that considerably extends the current technology is based on a moreflexible use of pixel memory, not supported by current architectures.The M-Buffer architecture described here divides pixel memory into general-purposebuffers, each associated with one processor. Pixel data is broadcast to all buffers simultaneously. Logical and numeric tests are performed by each processor and theresults are broadcast and used by all buffers in parallel to evaluate logical expressionsfor the pixel update condition.The architecture is scalable by addition of buffer-processors, suitable for pixel parallelization,and permits the use of buffers for different purposes. The architecture, its functional description, and a powerful programming interface are described.
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    Accelerating Polygon Clipping
    (The Eurographics Association, 1992) Schneider, Bengt-Olaf; P F Lister
    Polygon clipping is a central part of image generation and image visualization systems.In spite of its algorithmic simplicity it consumes a considerable amount of hardware or software resources. Polygon clipping performance is dominated by two processes: intersection calculations and data transfers. The paper analyzes the prevalent Sutherland-Hodgman algorithm for polygon clippingand identifies cases for which this algorithm performs inefficiently. Such casesare characterized by subsequent vertices in the input polygon that share a commonregion, e. g. a common halfspace.The paper will present new techniques that detect such constellations and simplifythe input polygon such that the Sutherland-Hodgman algorithm runs more efficiently. Block diagrams and pseudo-code demonstrate that the new techniques are well suited for both hardware and software implementations. Finally, the paper discusses the results of a prototype implementation of the presented techniques. The analysis compares the performance of the new techniquesto the traditional Sutherland-Hodgman algorithm for different test scenes. The new techniques reduce the number data transfers by up to 90 % and the number of intersection calculations by up to 60 %.