MODULATED AND BLENDED ANTI-ALIASING

• US 20140218390A1
• Filed: 02/05/2013
• Published: 08/07/2014
• Est. Priority Date: 02/05/2013
• Status: Active Grant

• Current Assignee: NVIDIA Corporation
• Original Assignee: NVIDIA Corporation
• Inventors: Rouet, Christian Jean, Lum, Eric Brian, Bastos, Rui Manuel
• Granted Patent: US 9,454,843 B2
• Time in Patent Office: Days
• US Class Current: 345/612
• CPC Class Codes: G06T 11/40 Filling a planar surface by adding surface attributes, e.g. colour or texture
• CPC Class Codes: G06T 15/405 using Z-buffer
• CPC Class Codes: G06T 15/503 Blending, e.g. for anti-aliasing

Abstract

A system, method, and computer program product are provided for anti-aliasing. During a first processing pass of a plurality of graphics primitives, z data is computed for multiple samples of each pixel in an image to generate a multi-sample z buffer. During a second processing pass of the graphics primitives, computed color values corresponding to each pixel in a color buffer that stores one color value for each pixel are accumulated.

Claims

1. A method of anti-aliasing, comprising:

computing z data for multiple samples of each pixel in an image to generate a multi-sample z buffer during a first processing pass of a plurality of graphics primitives; and

accumulating computed color values corresponding to each pixel into a color buffer that stores one color value for each pixel during a second processing pass of the graphics primitives.

2. The method of claim 1, further comprising scaling each sample color value based on a number of samples per pixel to generate modulated sample color values during the second processing pass.

3. The method of claim 2, further comprising combining the modulated sample color ues for each pixel during the second processing pass.

4. The method of claim 3, wherein the combining comprises summing the modulated color values for each sample of a pixel that is covered by a particular graphics primitive.

5. The method of claim 1, further comprising scaling a sample color value based on coverage and a number of samples per pixel to generate a combined modulated sample color value for a pixel during the second processing pass.

6. The method of claim 1, wherein a multi-sample stencil buffer is used during the second processing pass to compute only one color value for each sample that is covered by at least one of the graphics primitives

7. The method of claim 6, further comprising, prior to the second processing pass of the graphics primitives:

clearing the multi-sample stencil buffer to an initial value; and

setting a stencil function to pass for only one of two or more graphics primitives that cover a sample location when tested against a stencil value stored in the multi-sample stencil buffer for the sample location.

8. The method of claim 1, further comprising, prior to the second processing pass of the graphics primitives:

clearing the color buffer to an initial value; and

setting a color blend function to add color values.

9. The method of claim 1, further comprising prior to the first processing pass of the graphics primitives:

clearing the multi-sample z buffer to an initial value; and

setting a z test function to “

less than”

.

10. The method of claim 1, further comprising prior to the first processing pass of the graphics primitives:

clearing the multi-sample z buffer to an initial value; and

setting a z test function to “

less than or equal”

.

11. The method of claim 1, further comprising, prior to the second processing pass of the graphics primitives, setting a z test function to “

equal”

.

12. The method of claim 1, further comprising, during the second processing pass of the graphics primitives

determining that a sample location covered by a graphics primitive passes a z test;

determining that the sample location corresponds to a value indicating that a graphics primitive that covers the sample location has been processed during the second processing pass; and

discarding the sample location for the graphics primitive.

13. The method of claim 1, further comprising, during the second processing pass of the graphics primitives:

determining that a sample location covered by a graphics primitive passes a z test;

determining that the sample location corresponds to a value indicating that a graphics primitive that covers the sample location has not been processed during the second processing pass; and

updating the value.

14. A non-transitory computer-readable storage medium storing instructions that, when executed by a processor, cause the processor to perform anti-aliasing comprising:

computing z data for multiple samples of each pixel in an image to generate a multi-sample z buffer during a first processing pass of a plurality of graphics primitives; and

accumulating computed color values corresponding to each pixel into a color buffer that stores one color value for each pixel during a second processing pass of the graphics primitives.

15. The non-transitory computer-readable storage medium of claim 14, further comprising, scaling each sample color value based on a number of samples per pixel to generate modulated sample color values during the second processing pass.

16. The non-transitory computer-readable storage medium of claim 15, further comprising, combining the modulated sample color values for each pixel during the second processing pass.

17. The non-transitory computer-readable storage medium of claim 14, further comprising, prior to the second processing pass of the graphics primitives:

clearing the color buffer to an initial value; and

setting a color blend function to add color values.

18. A system comprising:

a memory storing a multi-sample z buffer, and a color buffer that stores one color value for each pixel; and

one or more processing units coupled to the memory and configured to;

compute z data for multiple samples of each pixel in an image and store the z data in the multi-sample z buffer during a first processing pass of a plurality of graphics primitives; and

accumulate the computed color values corresponding to each pixel into the color buffer during a second processing pass of the graphics primitives.

19. The system of claim 18, wherein the one or more processing units reside within a graphics processing unit.

20. The system of claim 18, wherein the one or more processing units are further configured to scale a sample color value based on coverage and a number of samples per pixel to generate a combined modulated sample color value for a pixel during the second processing pass.