Smooth rasterization of polygonal graphics primitives

Abstract

A method and system for smooth rasterization of graphics primitives. The method includes receiving a graphics primitive for rasterization in a raster stage of a processor, rasterizing the graphics primitive by generating a plurality of fragments related to the graphics primitive, and determining a coverage value for each of the plurality of fragments. If one edge of the graphics primitive lies within a predetermined inter-pixel distance from a pixel center, the one edge is used to calculate the coverage value by using a distance to the pixel center. If two edges of the graphics primitive lie within the predetermined inter-pixel distance from the pixel center, a distance to the pixel center of each edge is used individually to calculate the coverage value. The resulting coverage values for the plurality of fragments are output to a subsequent stage of the processor for rendering.

Description

[0001]This application is a continuation of U.S. patent application Ser. No. 11 / 592,826, SMOOTH RASTERIZATION OF POLYGONAL GRAPHICS PRIMITIVES, by Franklin C. Crow, filed on Nov. 2, 2006, attorney docket number NVID-P002084.CROSS REFERENCE TO RELATED APPLICATION[0002]This application is related to the commonly assigned United States Patent Application APPARATUS, SYSTEM, AND METHOD FOR GAMMA CORRECTION OF SMOOTH PRIMITIVES, by Crow et al., filed on ______, attorney docket number NVID-P000680, and is incorporated herein in its entirety.FIELD OF THE INVENTION[0003]The present invention is generally related to hardware accelerated graphics computer systems.BACKGROUND OF THE INVENTION[0004]Recent advances in computer performance have enabled graphic systems to provide more realistic graphical images using personal computers, home video game computers, handheld devices, and the like. In such graphic systems, a number of procedures are executed to “render” or draw graphic primitives to the...

AI Technical Summary

Benefits of technology

The present invention provides a method and system for generating high-quality anti-aliased images while minimizing the additional overhead computations needed to support such anti-aliasing. The method includes rasterizing graphics primatives and determining coverage values for each fragment generated during rasterization. The method also uses a predetermined distance to calculate the coverage value for each edge of the graphics primitive. The resultant coverage values are output for rendering. This approach improves the quality of anti-aliased images while optimizing processing efficiency.

Problems solved by technology

A problem exists however with the ability of prior art 3D rendering architectures to efficiently handle high-quality anti-aliasing of the complex 3D scenes of modern real-time 3D applications.

Aliasing artifacts result from the fact that the images are drawn against a finite resolution grid of pixels of a frame buffer.

The implementation of high-quality anti-aliasing imposes a heavy computational burden on the graphics rendering pipeline.

However, computing fragment area directly from its shape is very processor intensive, since the shape of a fragment can vary depending upon the polygon's shape and orientation.

The high computational burden required for high-quality anti-aliasing has led to a number of prior art shortcut schemes to provide anti-aliased image quality while reducing the computational workload.

However each of these prior art schemes involve trade-offs in the accuracy of the estimation of fragment area, in image quality, and in computational speed.

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