System and method for producing an antialiased image using a merge buffer

Image processing apparatus comprising:

• fragment storage storing fragment tuples, each stored fragment tuple being associated with a fragment in a pixel of an image having a plurality of pixels, the image having multiple surfaces, each surface tessellated into primitive objects;
• each fragment tuple including a color value and a depth value;
• a merge pipeline processing circuit for processing a new fragment tuple representing a fragment to be added to the image, the pipeline processing circuit including a sequence of pipeline stage circuits, including:
• a tag comparison stage circuit for identifying a potentially mergable fragment tuple, comprising one of the fragment tuples in the fragment storage;
• the new fragment tuple having associated therewith a first object comprising a respective primitive object of said primitive objects, and the potentially mergable fragment tuple having associated therewith a second object selected from a group consisting of a respective primitive object of said primitive objects and a union of a plurality of respective primitive objects of said primitive objects;
• an evaluation stage circuit for generating an outcome based on whether predefined merge criteria are met, the predefined merge criteria include criteria that probabilistically establish that the object associated with the new fragment tuple is adjacent to the object associated with the potentially mergable fragment tuple, that the new fragment tuple and potentially mergable fragment tuple are associated with fragments from a common tessellated surface of the multiple surfaces, and that the first and second fragments are sufficiently similar to avoid visually objectionable artifacts when the first and second fragments are merged;
• a fragment merging stage circuit for merging the color values and depth values of the new fragment tuple and the potentially mergable fragment tuple to generate a merged fragment tuple based on the outcome of the evaluation stage;
• and
• an update fragment storage stage circuit for storing the merged fragment tuple in the fragment storage if the predefined merge criteria are met, and for storing the new fragment tuple in the fragment storage if the predefined merge criteria are not met.

A method of rendering an image, the method comprising:

• generating fragments for the image, the image having multiple surfaces, each surface tessellated into primitive objects;
• the image including a pixel having associated therewith a first and a second fragment;
• the first fragment being one of the generated fragments and having associated therewith an object comprising a respective primitive object of said primitive objects, and the second fragment being selected from a group consisting of a generated fragment and having associated therewith an object comprising a respective primitive object of said primitive objects, and a combination of a plurality of generated fragments and having associated therewith an object comprising a union of a plurality of respective primitive objects of said primitive objects;
• conditionally merging the first fragment with the second fragment to create a new merged fragment that replaces the first and second fragment when predefined merge criteria are met, the predefined merge criteria include criteria that probabilistically establish that the first fragment's associated object is adjacent to the second fragment's associated object, that the first and second fragments are from a common tessellated surface of the multiple surfaces, and that the first and second fragments are sufficiently similar to avoid visually objectionable artifacts when the first and second fragments are merged;
• and
• storing in a frame buffer fragments from among the generated fragments and the new merged fragment, combining the fragments into pixels and outputting the pixels to a display.

A method of rendering an image, the image having a plurality of pixels, the image furthermore having multiple surfaces, each surface tessellated into primitive objects;

• the method comprising:
• storing fragment tuples, each stored fragment tuple being associated with a fragment in a pixel of the image, each fragment tuple including a color value and a depth value;
• processing a new fragment tuple representing a fragment to be added to a particular pixel of the plurality of pixels, the new fragment tuple having a color value and a depth value;
• the processing of the new fragment tuple including:
• comparing the new fragment tuple and a selected fragment tuple of the stored fragment tuples to generate a merge outcome based on whether predefined merge criteria are met, the new fragment having associated therewith a first object comprising a respective primitive object of said primitive objects, and the selected fragment having associated therewith a second object selected from a group consisting of a respective primitive object of said primitive objects and a union of a plurality of respective primitive objects of said primitive objects;
• the predefined merge criteria include criteria that probabilistically establish that the first object, associated with the new fragment tuple, is adjacent to the second object, associated with the selected fragment tuple, that the new fragment tuple and selected fragment tuple are associated with fragments from a common tessellated surface of the multiple surfaces, and that the first and second fragments are sufficiently similar to avoid visually objectionable artifacts when the first and second fragments are merged;
• and
• merging the new fragment tuple with the selected fragment tuple to produce a merged fragment tuple when the merge outcome has a predefined value.