Drawing 'polygon with edge'-type primitives in a computer graphics display system.

摘要

In a computer graphics display system, a method and processor are disclosed for drawing a 'polygon with edge'-type primitive encountered in certain high level graphics interface programs. Both the method and processor use a mask buffer organized into a plurality of addressable M x N constituent pixels, each pixel preferably being two bits deep. The method includes: masking the pixels in the mask buffer corresponding to the boundary to the polygon; drawing the pixels in the frame buffer of the display system corresponding to the boundary of the polygon; and drawing the pixels in the frame buffer corresponding to the interior of the polygon with reference to the content of the mask buffer. Corresponding processing steps for writing Z values in a depth buffer are also described. In addition, specific algorithms for implementing the method are set forth, along with an embodiment of a display processor implementing the method.