Method and system for filling non-complex polygons using vertical spans

摘要

A method and system for rendering and filling non-complex polygon outlines using vertical span architecture. Three control planes are used to control the rendering and filling of pixels. These control planes include a fill control plane, which is filled with bits at locations corresponding to the first and last points of each vertical span of a polygon outline; an edge plane, which is filled with bits at locations corresponding to pixels having a center lying on an oblique edge of the polygon outline or having a center lying on a beginning or ending of each edge; and a Y direction plane, which is filled with bits indicating whether the edge is directed in a positive or negative Y direction at locations corresponding to the filled locations in the edge plane. The polygon is filled by proceeding along successive vertical spans, processing each span in accordance with the contents of the three control planes and the rendering orientation of the polygon outline.