US Patent 7652677 Graphics system employing pixel mask

The system includes a bounds primitive rasterizer that rasterizes a bounds primitive into a selection of primitive pixels. The selection of primitive pixels bounds a shape to be rendered to a screen. The system also includes a pixel mask generator that generates a pixel mask for the shape. The pixel mask includes mask pixels that each corresponds to one of the primitive pixels. A mask pixel is a covered pixel when the shape covers at least a threshold portion of the mask pixel and is an uncovered pixel when the shape does not cover the mask pixel. The system also includes a pixel screener configured to retain primitive pixels that correspond to covered mask pixels and to discard primitive pixels that correspond to uncovered mask pixels.