Patent ID: 7750922

Claim:
A system, comprising: one or more graphics processors; and memory coupled to the one or more graphics processors, comprising: a frame buffer configured to store both color and alpha information, wherein the alpha information indicates a level of opacity for the color information; and wherein the memory stores program instructions executable by the one or more graphics processors to: render one or more previous transparency groups to the frame buffer, wherein a transparency group is a composition of a plurality of graphics objects, wherein each of the plurality of graphics objects has an individual transparency level, and wherein the plurality of graphics objects are composited to form the transparency group dependent on the individual transparency level of each of the plurality of graphics objects, and wherein a transparency group is rendered as a single object according to a level of transparency associated with the transparency group, and wherein each of the one or more previous transparency groups comprise color information pre-multiplied with alpha information; store a copy of the frame buffer including image information for the one or more previous transparency groups to a separate buffer; render a new transparency group to the frame buffer using a Porter-Duff blending formula, wherein the new transparency group comprises color information pre-multiplied with alpha information; and combine the copy of the frame buffer from the separate buffer with the rendered new transparency group using the Porter-Duff blending formula.