ARC SPLINE GPU RASTERIZATION FOR CUBIC BEZIER DRAWING

摘要

A curve drawing system is described herein that rasterizes arc splines in the GPU of a computer for cubic Bezier drawing of strokes and thin features. The curve drawing system first converts a cubic Bezier representation into an arc spline representation. Then the curve drawing system uses a similar approach to Loop/Blinn modified to cause the pixel shader to perform a point-in-circular-arc test instead of a point-in-Bezier test. Calculating arc radius is a much simpler operation than the alternatives and can be easily and efficiently performed by the pixel shader. Since the stroke of an arc spline is also an arc spline, the drawing system provides a resolution-independent representation of strokes. Thus, the curve drawing system allows several previously difficult graphical features to be efficiently drawn by readily available legacy hardware and used in software programs that are designed to run on a wide variety of hardware.