Method and apparatus for resolving pixel data in a graphics rendering system

A pixel resolution circuit for resolving pixel data for a pixel location having n sub-pixel regions, where n is an integer comprising:

• a fragment buffer storing depth-sorted fragment records for a pixel location, each fragment record including color data, an alpha value, and pixel coverage data indicating which of the n sub-pixel regions the fragment record covers;
• a new coverage control in communication with the fragment buffer, the new coverage control for analyzing pixel coverage data, for identifying unique pixel regions including sub-pixels having common accumulated alpha values, and for storing the common accumulated alpha values for the pixel regions;
• and
• a scale and accumulation control in communication with the new coverage control and the fragment buffer, the scale and accumulation control coupled to the fragment buffer for receiving the color, alpha, and pixel coverage data, the color accumulation circuitry having color scale and color accumulation circuitry for computing accumulated color for the unique pixel regions having common accumulated alpha values.

A method for resolving pixel data for contiguous 2D subregions of an image being rendered, the method comprising:

• successively processing fragment records for pixel locations in a 2D subregion such that each subregion for the image is resolved in a serial order, the fragment records including color data and pixel coverage data corresponding to n sub-pixel regions, where n is an integer;
• separately accumulating color for the n sub-pixel regions;
• storing the accumulated color for the n sub-pixel regions;
• and
• combining the accumulated color for the n sub-pixel regions to compute a color value for a pixel location.

A method for resolving pixel data for a pixel location having n sub-pixel regions, where n is an integer, the method comprising:

• reading a current fragment record from a depth sorted list of fragment records, each fragment record including color data, an alpha value, and pixel coverage data identifying which of the n sub-pixel regions that the fragment record covers;
• analyzing the pixel coverage data of the current fragment to identify one or more unique pixel regions, each having one or more sub-pixel regions having a common accumulated alpha;
• for each of the one or more unique pixel regions, scaling the color data for the current fragment by multiplying the color data for the current fragment by the common accumulated alpha for the pixel region, the alpha value of the current fragment, and a coverage scale factor, where the coverage scale factor is m/n and m is the number of sub-pixel regions in the pixel region;
• and
• adding the scaled color data with accumulated color data for the pixel location;
• repeating analyzing, scaling and adding steps for subsequent fragments in the depth sorted list.