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High-Quality Polygon Edging
July 1995 (vol. 15 no. 4)
pp. 68-74
Although drawing vectors between polygon vertices appears to be an easy way to highlight borders, standard graphics techniques can produce many unwanted artifacts. Scan conversion algorithms often generate significantly different z-buffer values for polygon fill pixels and the associated vector (edge) pixels. Where edge vectors overlap polygon fill, inconsistent z-buffer values may cause edge pixels to be overwritten by fill. The result is poor quality polygon edging, a problem which has become pervasive in graphics hardware. We present an algorithm which uses an edging plane to generate high quality polygon edges when using separately drawn vectors to highlight polygon borders. The algorithm maintains the subpixel adjustments necessary for accurate polygonal rendering. The edging plane is simple to incorporate into existing software and hardware scan convertors. We include a comparison of our algorithm with existing methods for improving polygon edges.

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Index Terms:
CR Categories and Subject Descriptors: [Computer Graphics]: I.3.1 Hardware Architecture - raster display devices; I.3.3 Picture/Image Generation - display algorithms; I.3.7 Three-Dimensional Graphics and Realism - visible surface algorithms.
Citation:
Russ Herrell, Joe Baldwin, Chris Wilcox, "High-Quality Polygon Edging," IEEE Computer Graphics and Applications, vol. 15, no. 4, pp. 68-74, July 1995, doi:10.1109/38.391494
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