Method and system for efficiently using fewer blending units for antialiasing

A method for providing antialiasing of a graphical image on a display, the graphical image provided from data describing at least one object, the display including a plurality of pixels, the at least one object including a plurality of fragments, a portion of the plurality of fragments intersecting a pixel of the plurality of pixels, each of the plurality of fragments including a coverage mask indicating of a portion of a corresponding pixel that is intersected, the method comprising the steps of:

• (a) providing at least one active region for the pixel, each of the at least one active region intersecting a first portion of the pixel;
• (b) intersecting the coverage mask for the fragment with each of the at least one active region to provide an intersection mask for each of the at least one active region;
• (c) for each of the at least one active region, updating an active region of the at least one active region if the intersection mask is the same as the active region;
• (d) for each of the at least one active region that is not the same as the intersection mask, splitting the active region into a first new region and a second new region, the first new region being the intersection mask and the second new region being a complement of the intersection mask, the first new region being added to the at least one active region and the second new region an update of the active region;
• (e) blending a portion of the fragment in a second portion of the pixel corresponding to the intersection mask for each of the at least one active region;
• and
• (f) repeating steps (b) through (e) for each of the plurality of fragments intersecting the pixel.

A system for providing antialiasing of a graphical image from data describing at least one object, the at least one object including a plurality of fragments, the system comprising:

• a display including a plurality of pixels, each of the plurality of pixels including a number of subpixels;
• means coupled to the display for providing a plurality of fragments for the at least one object, the plurality of fragments intersecting the plurality of pixels, each of the plurality of fragments including an indication of a portion of a corresponding pixel that is intersected;
• an antialiasing unit, coupled with the display, for providing antialiasing of each of the plurality of fragments based on the indication of the extent a corresponding pixel is intersected, the antialiasing unit further including
• an accumulator for storing data relating to the pixel;
• a region generator coupled with the accumulator for indicating at least one active region for the pixel and at least one new region, each of the at least one active region intersecting a portion of the pixel, the at least one new region being based on an intersection between the at least one active region and the fragment, a first portion of the at least one new region indicating where in the pixel the at least one active region and the fragment intersect, a second portion of the at least one new region indicating where in the pixel the at least one active region and the fragment do not intersect, the region generator indicating the first portion of the at least one new region to be blended;
• and
• a blending unit coupled with the accumulator and the region providing, the blending unit blending a portion of the fragment in the first portion of the at least one new region in the fragment;
• and
• wherein the region generator further includes a region list for indicating the at least one active region for the pixel.

A computer-readable medium containing a program for antialiasing a graphical image on a display, the graphical image provided from data describing at least one object, the display including a plurality of pixels, the at least one object including a plurality of fragments, a portion of the plurality of fragments intersecting a pixel of the plurality of pixels, each of the plurality of fragments including an indication of a portion of a corresponding pixel that is intersected, the program including instructions for:

• (a) providing at least one active region for the pixel, the at least one active region intersecting a first portion of the pixel;
• (b) providing at least one new region, a first portion of the at least one new region indicating where in the pixel the at least one active region and the fragment intersect, a second portion of the at least one new region indicating where in the pixel the at least one active region and the fragment do not intersect;
• and
• (c) blending a portion of the fragment in a second portion of the pixel corresponding to the first portion of the at least one new region.

A computer-readable medium containing a program for providing antialiasing of a graphical image on a display, the graphical image being provided from data describing at least one object, the display including a plurality of pixels, the at least one object including a plurality of fragments, a portion of the plurality of fragments intersecting a pixel of the plurality of pixels, each of the plurality of fragments including a coverage mask indicating of a portion of a corresponding pixel that is intersected, the program including instructions for:

• (a) providing at least one active region for the pixel, each of the at least one active region intersecting a first portion of the pixel;
• (b) intersecting the coverage mask for the fragment with each of the at least one active region to provide an intersection mask for each of the at least one active region;
• (c) for each of the at least one active region, updating an active region of the at least one active region if the intersection mask is the same as the active region;
• (d) for each of the at least one active region that is not the same as the intersection mask, splitting the active region into a first new active region and a second new region, the first new region being the intersection mask and the second new region being a complement of the intersection mask;
• (e) blending a portion of the fragment in a second portion of the pixel corresponding to the intersection mask for each of the at least one active region;
• and
• (f) repeating steps (b) through (e) for each of the plurality of fragments intersecting the pixel.

An antialiasing unit for providing antialiasing of a graphical image from data describing at least one object on a display, the display including a plurality of pixel, each of the plurality of pixels including a number of subpixels, the at least one object including a plurality of fragments intersecting the plurality of pixels, each of the plurality of fragments including an indication of a portion of a corresponding pixel that is intersected, the antialiasing unit comprising:

• an accumulator for storing data relating to the pixel;
• a region generator coupled with the accumulator for indicating at least one active region for the pixel and at least one new region, each of the at least one active region intersecting a portion of the pixel, the at least one new region being based on an intersection between the at least one active region and the fragment, a first portion of the at least one new region indicating where in the pixel the at least one active region and the fragment intersect, a second portion of the at least one new region indicating where in the pixel the at least one active region and the fragment do not intersect, the region generator indicating the first portion of the at least one new region to be blended, the region generator further including a region list for indicating the at least one active region for the pixel;
• and
• a blending unit coupled with the accumulator and the region providing, the blending unit blending a portion of the fragment in the first portion of the at least one new region in the fragment.