Method and apparatus for determining simple convex polygons

摘要

An accelerated video controller operates in conjunction with a video driver to accelerate certain video operations. If the operating environment requests a polygon operation, the driver (or software on the video controller) will determine whether the specified polygon is simple convex. The determination of whether a convex polygon is simple convex is accomplished by tracing between the vertices of the polygon and comparing the changes in direction relative to a predetermine coordinate axis to a threshold number. If the polygon is simple convex, certain operations can be performed using simpler code or hardware accelerated features. For a polygon fill, if the polygon is simple convex, the edges of the polygon are inspected to determine whether the polygon can be decomposed into a rectangle and a smaller polygon. If so, the video controllers bit engine will be used to perform the fill of the rectangle at high speed, thus reducing the time of the operation.