SEGMERGE: A Scanline Visible Surface Algorithm with Adaptive Span Selection and Inexpensive Antialiasing

摘要

Spanning scanline algorithms are efficient because they take advantage of scanline and span coherence. An entire horizontal ''span'' can be declared visible at once, thus avoiding comparisons at each pixel. It is important that the number of spans be minimized because depth comparisons are made at each one. This paper presents two new techniques for scanline visible surface rendering: first, a span selection method which minimizes the number of spans and discards invisible segments; second, an inexpensive antialiasing method. It will be shown that subpixel sampling for antialiasing requiring N sup 2 times more work for point sampling algorithms can be done with only N times more work for spanning scanline algorithms. 15 refs., 4 figs. (ERA citation 13:032032)