Method and apparatus for averaging sub-samples
A method of generating pixels in a graphics system including providing a plurality of sub-samples, and providing a source pixel. It is determined which of the plurality of sub-samples are covered by the source pixel, and which of the plurality of sub-samples are not covered. The sub-samples which are covered by the source pixel are filtered. The filtered sub-samples are blended with the source pixel to create a blended sub-sample, followed by the filtering of the sub-samples which are not covered by the source pixel together with the blended sub-sample.
1. A method of generating pixels in a graphics system comprising:
providing a plurality of sub-samples;
providing a source pixel;
determining which of the plurality of sub-samples are covered by the source pixel, and which of the plurality of sub-samples are not covered by the source pixel;
filtering the sub-samples which are covered by the source pixel;
blending the filtered sub-samples with the source pixel to create a blended sub-sample; and
filtering the sub-samples which are not covered by the source pixel together with the blended sub-sample.
2. The method of claim 1 wherein the filtering the sub-samples which are covered by the source pixel, is done by averaging the sub-samples which are covered by the source pixel.
3. The method of claim 2 wherein the filtering the sub-samples which are not covered by the source pixel together with the blended sub-sample, is done by averaging the sub-samples which are not covered by the source pixel together with the blended sub-sample.
4. The method of claim 3 further comprising before the filtering the sub-samples which are not covered by the source pixel together with the blended sub-sample, weighting the blended sub-sample.
5. The method of claim 4 further comprising before weighting the blended sub-sample, determining the number of covered sub-samples,
and wherein the weighting of the blended sub-sample is done by multiplying the blended sub-sample by the number of covered sub-samples.
6. The method of claim 1 further comprising replacing the sub-samples which are covered by the source pixel with the blended sub-sample.
7. An apparatus for generating pixels in a graphics system comprising:
a memory for storing and providing sub-samples;
a graphics pipeline for providing an image, and determining which sub-samples are covered by the image, and which sub-samples are not covered by the image;
a first filter for filtering covered sub-samples and providing a first filter output;
a blender for blending the image with the output of the first filter and providing a blender output; and
a second filter for filtering the blender output with the sub-samples which are not covered by the image.
8. The apparatus of claim 7 wherein the first filter and the second filer are averaging circuits.
9. The apparatus of claim 8 wherein the second filter is also for weighting the blender output.
10. The apparatus of claim 7 wherein the blender output provides anew sub-sample, and where the new sub-sample replaces in memory the sub-samples covered by the image.
11. An apparatus for generating pixels in a graphics system comprising:
a sub-sample memory having an first output and a second output;
a fist filter having an output and an input, the input coupled to the first sub-sample memory output;
a blender having an output, a first input, and a second input, the first input coupled to the first filter output;
a graphics pipeline having an output coupled to the second blender input; and
a second filter having a first input and a second input, the first input coupled to the second sub-sample memory output and the second input coupled to the blender output.
12. The apparatus of claim 11 wherein the sub-sample memory stores a plurality of sub-samples which are associated with a pixel, and wherein the graphics pipeline provides a source pixel, and determines which of the sub-samples associated with the pixel are covered by the source pixel, and which of the sub-samples associated with the pixel are not covered by the source pixel.
13. The apparatus of claim 12 wherein the sub-sample memory outputs on the first sub-sample memory output the sub-samples associated with the pixel which are covered by the source pixel and outputs on the second sub-sample memory output the sub-samples associated with the pixel which are not covered by the source pixel.
14. The apparatus of claim 13 wherein first filter averages the sub-samples at its input, and outputs an average, and the blender blends the signals at its inputs, and outputs a blend.
15. The apparatus of claim 14 wherein the second filter filters the sub-samples at its first input and the blend at its second input.
16. The apparatus of claim 15 wherein the second filter further comprises an output for providing a pixel.
17. A computer system comprising:
a central processing unit (CPU);
a main memory coupled to the CPU; and
an apparatus for generating pixels in graphics system as set forth in claim 11 , coupled to the CPU.
18. A method of generating pixels in a graphics system comprising:
receiving a plurality of sub-samples from a memory;
receiving a source pixel;
receiving coverage information indicating which of the plurality of sub-samples are covered by the source pixel, and which of the plurality of sub-samples are not covered by the source pixel;
filtering the sub-samples that are covered by the source pixel;
blending the filtered sub-samples with the source pixel to create a blended sub-sample;
storing the blended sub-sample in the memory, overwriting the sub-samples that are covered by the source pixel; and
filtering the sub-samples that are not covered by the source pixel together with the blended sub-sample.
19. The method of claim 18 wherein when the sub-samples that are not covered by the source pixel are filtered with the blended sub-sample, the blended sub-sample is first multiplied by the number of sub-samples covered by the source pixel.
20. The method of claim 19 wherein the source pixels is received from a graphics pipeline.
21. A method of generating pixels in a graphics system using a single blender, the method comprising:
receiving a plurality of sub-samples;
receiving a source pixel;
receiving coverage information as to which of the plurality of sub-samples are covered by the source pixel, and which of the plurality of sub-samples are not covered by the source pixel;
filtering the sub-samples which are covered by the source pixel to generate a filtered result;
using a single blender to blend the filtered result and the source pixel to create a blended sub-sample; and
filtering the sub-samples which are not covered by the source pixel together with the blended sub-sample.
22. The method of claim 21 wherein filtering the sub-samples which are covered by the source pixel, is done by averaging the sub-samples which are covered by the source pixel.
23. The method of claim 22 wherein the filtering the sub-samples which are not covered by the source pixel together with the blended sub-sample, is done by averaging the sub-samples which are not covered by the source pixel together with the blended sub-sample.
24. A method of generating pixels in a graphics system comprising:
receiving a plurality of sub-samples;
receiving a source pixel;
receiving coverage information as to which of the plurality of sub-samples are covered by the source pixel, and which of the plurality of sub-samples are not covered by the source pixel;
during a first clock cycle, filter the sub-samples which are covered by the source pixel to generate a filtered result;
during a second clock cycle, blending the filtered result with the source pixel to create a blended sub-sample; and
during a third clock cycle, filtering the sub-samples which are not covered by the source pixel together with the blended sub-sample,
wherein the second clock cycle occurs after the first clock cycle and before the third clock cycle.
25. The method of claim 24 wherein the filtering the sub-samples which are covered by the source pixel, is done by averaging the sub-samples which are covered by the source pixel.
26. The method of claim 25 wherein the filtering the sub-samples which are not covered by the source pixel together with the blended sub-sample, is done by averaging the sub-samples which are not covered by the source pixel together with the blended sub-sample.
27. The method of claim 26 further comprising before the filtering the sub-samples which are not covered by the source pixel together with the blended sub-sample, weighing the blended sub-sample.
28. The method of claim 27 further comprising before weighting the blended sub-samples determining the number of covered sub-samples,
wherein the weighing of the blended sub-sample is done by multiplying the blended sub-sample by the number of covered sub-samples.