Polygon display based on x coordinates of edges on scan line

摘要

Image data is processed so that polygons can be displayed on a screen of scanned lines. A first memory stores at least X and Y coordinate data for edge points of the polygons. A second memory stores polygon numbers arranged in a processing order. A first computing unit computes data for sides of each polygon corresponding to each polygon number stored in the second memory. A second computing unit computes edge pair data in accordance with the data for sides of polygons, the edge pair data including a pair of edge points located on the scan lines. A third computing unit computes data for a start point and an end point of each polygon based on the edge pair data. Finally, a processing unit processes the start point and end point data to obtain polygon dot data and outputs the dot data in synchrony with the scan lines.