Texture alpha discrimination a method and apparatus for selective texture modulation in a real time graphics pipeline

• US 6,323,870 B1
• Filed: 06/07/1999
• Issued: 11/27/2001
• Est. Priority Date: 06/07/1999
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Newhall, William Parsons Jr.
• Primary Examiner(s): BRIER, JEFFERY A
• Application Number:
  US09/327,016
• Time in Patent Office: 904 Days
• Field of Search: 345/430, 345/582
• US Class Current: 345/582
• CPC Class Codes: G06T 15/04 Texture mapping

Abstract

A process, referred to as alpha discrimination, for processing a texture data value in a computer graphics display system. With a preferred embodiment, the process of alpha discrimination occurs during the rendering of a drawing primitive between the stages of texture memory fetch and texture filter in the traditional graphics pipeline. After an initial texture data value is fetched, or identified, a determination is made as to whether the discrimination procedure is enabled or not enabled. If that procedure is not enabled, then the initial texture data value is passed to a predetermined element of the graphics display system, such as the texture filter. But if the discrimination procedure is enabled, then a preset test is performed. The initial texture data value is processed on the basis of the result of the test to produce a processed texture data value, and that processed texture data value is then passed to the predetermined element of the graphics display system.

Claims

1. A method in a computer graphics display system for processing a texture data value, the method comprising:

identifying an initial texture data value including more than one component;

determining whether a discrimination procedure is enabled or not enabled;

if the discrimination procedure is enabled, then performing a preset test on a component of the texture data value not representing color or distance;

processing the initial texture data value on the basis of the result of the test to produce a processed texture data value; and

passing the processed texture data value to a predetermined element of the graphics display system.

2. A method according to claim 1, wherein the test has one of two results, and the processing step includes the steps of:

processing the initial texture data value according to a first procedure if the test has a first of the two results;

processing the initial texture data value according to a second procedure if the test has a second of the two results.

3. A method according to claim 2, wherein the first procedure is to set the processed texture data value equal to the initial texture data value.

4. A method according to claim 2, wherein the second procedure is to reset the initial texture value to a preset constant value to obtain the processed texture data value.

5. A method according to claim 1, wherein the performing step includes the step of comparing a predetermined reference value with a pre-identified parameter of the texture data value not representing color or distance.

6. A method according to claim 5, wherein the comparing step includes the step of determining if the value of the pre-identified parameter is equal to the predetermined reference value.

7. A method according to claim 5, wherein the comparing step includes the step of determining if the value of the pre-identified parameter is less than the predetermined reference value.

8. A method according to claim 5, wherein the comparing step includes the step of determining if the value of the pre-identified parameter is greater than the predetermined reference value.

9. A method according to claim 5, wherein the comparing step includes the step of determining if the value of the pre-identified parameter is equal to zero.

10. A method according to claim 1, wherein:

the initial texture data value is a fetched texture data value and has a preset number of component bits; and

the step of processing the initial texture data value includes the steps of

i) identifying a predetermined subset of said number of bits, and

ii) processing the predetermined subset of said number of bits according to the test results.

11. A method according to claim 10, wherein the step of performing a preset test includes the steps of:

defining a group of tests;

identifying one of the group of tests; and

performing the identified one of the group of tests;

wherein texture data can be tested by all, none or some of the defined tests, and wherein it is only necessary to get a TRUE result on one of the enabled tests for the texture data to be processed as TRUE.

12. A method according to claim 11, further including the step of providing a state variable that both identifies the one of the group of tests and identifies the predetermined subset of the number of bits.

13. A method according to claim 12, wherein the state variable also identifies whether the discrimination procedure is enabled or not enabled.

14. A method according to claim 1, further comprising the step of performing alpha discrimination on every texture data element which goes to a texture filter.

15. Apparatus for processing a texture data value in a computer graphics display system, the apparatus comprising:

means for identifying an initial texture data value including more than one component;

means for determining whether a discrimination procedure is enabled or not enabled;

means for performing a preset test on a component of the texture data value not representing color or distance if the discrimination procedure is enabled;

means for processing the initial texture data value on the basis of the result of the test to produce a processed texture data value; and

means for passing the processed texture data value to a predetermined element of the graphics display system.

16. Apparatus according to claim 15, wherein the test has one of two results, and the processing means includes:

means for processing the initial texture data value according to a first procedure if the test has a first of the two results; and

means for processing the initial texture data value according to a second procedure if the test has a second of the two results.

17. Apparatus according to claim 16, wherein the first procedure is to set the processed texture data value equal to the initial texture data value.

18. Apparatus according to claim 16, wherein the second procedure is to reset the initial texture value to a preset constant value to obtain the processed texture data value.

19. Apparatus according to claim 15, wherein the performing means includes means for comparing the value of a pre-identified parameter with a predetermined reference value.

20. Apparatus according to claim 19, wherein the comparing means comprises means for determining if the value of the pre-identified parameter is equal to the predetermined reference value.

21. Apparatus according to claim 19, wherein the comparing means includes means for determining if the value of the pre-identified parameter is less than the predetermined reference value.

22. Apparatus according to claim 19, wherein the comparing means includes means for determining if the value of the pre-identified parameter is greater than the predetermined reference value.

23. Apparatus according to claim 19, wherein the comparing means includes means for determining if the value of the pre-identified parameter is equal to zero.

24. Apparatus according to claim 15, wherein:

the initial texture data value is a fetched texture value and has a preset number of component bits; and

the processing means includes

i) means for identifying a predetermined subset of said number of bits, and

ii) means for processing the predetermined subset of said number of bits on the basis of the test results.

25. Apparatus according to claim 24, wherein the performing means includes:

means defining a group of tests;

means for identifying one of the group of tests; and

means for performing the identified one of the group of tests;

wherein texture data can be tested by all, none or some of the defined tests, and wherein it is only necessary to get a TRUE result on one of the enabled tests for the texture data element to be processed as TRUE.

26. Apparatus according to claim 25, further including means for holding a state variable that both identifies the one of the group of tests and identifies the predetermined subset of the number of bits.

27. Apparatus according to claim 26, wherein the state variable also identifies whether the discrimination procedure is enabled or not enabled.

28. A 3D graphics rasterizer chip, comprising:

a chip substrate;

a texture memory fetch circuit formed on the chip substrate for fetching initial texture data values including more than one component from a memory containing texture data;

a texture filter circuit formed on the chip substrate for filtering texture values; and

an alpha discriminator unit formed on the chip substrate for processing the initial texture data values, and including

i) a determination circuit to determine whether a discrimination procedure is enabled or not enabled,

ii) a test circuit to perform a preset test on a component of the texture data value not representing color or distance if the discrimination procedure is enabled,

iii) a processing circuit to process the initial texture data values on the basis of the result of the test to produce processed texture data values, and

iv) an output to pass the processed texture data values to the texture filter circuit if the discrimination procedure is enabled.

29. A graphics rasterizer chip according to claim 28, wherein the test has one of two results, and the processing circuit includes:

a first subcircuit for processing the initial texture data value according to a first procedure if the test has a first of the two results; and

a second subcircuit for processing the initial texture data value according to a second procedure if the test has a second of the two results.

30. A graphics rasterizer chip according to claim 28, wherein the test circuit includes means for performing a plurality of different types of tests.

31. A graphics rasterizer chip according to claim 28, wherein the initial texture values have a predetermined number of component bits, and the processing circuit includes:

means for holding a state variable identifying a subset of said number of component bits; and

means for processing the subset of said number of component bits according to the results of the test.

32. An article of manufacture for use with a computer graphics display system having a texturing function, wherein the texturing function includes a memory containing texture data including more than one component and an alpha discriminator unit for processing the texture data, and wherein the alpha discriminator unit includes a test circuit for performing a plurality of types of tests on a component of the texture data not representing color or distance, and a processing circuit for processing the texture data according to the results of the test to produce processed texture data values, the article of manufacture comprising:

a computer usable medium having computer readable program code embodied therein for causing the alpha discriminator unit to perform a particular one of said plurality of types of tests.

33. An article of manufacture according to claim 32, wherein said plurality of tests include a group of tests in which a predefined parameter is compared to a reference value, and wherein said computer readable program code gives a value for the reference value.

34. An article of manufacture according to claim 32, wherein the alpha discriminator unit further includes means to determine whether a discrimination procedure is enabled or not enabled, and the test circuit performs said tests if the discrimination procedure is enabled, and wherein the computer readable program code includes a state variable that indicates whether the discrimination procedure is enable or not enabled.

35. An article of manufacture for use with a computer graphics display system having a texturing function, wherein the texturing function includes a memory containing texture data including more than one component and an alpha discriminator unit for processing the texture data, the article of manufacture comprising:

a computer usable medium having computer readable program code embodied therein for causing the texturing function (i) to identify a texture data, (ii) to determine whether a discrimination procedure is enabled or not enabled, (iii) if the discrimination procedure is enabled, to perform a test on a component of the texture data not representing color or distance, and to modify the texture according to the results of the test.

36. An article of manufacture according to claim 35, wherein said computer readable program code provides said test.

37. An article of manufacture according to claim 35, wherein the computer readable program code includes a state variable that indicates whether the discrimination procedure is enabled or not enabled.

38. A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for processing a texture data value in a computer graphics display system, said method steps comprising:

identifying an initial texture data value having more than one component;

determining whether a discrimination procedure is enabled or not enabled;

if the discrimination procedure is enabled, then performing a preset test on a component of the texture data value not representing color or distance;

processing the initial texture data value according to the results of the test to produce a processed texture data value.

39. A program storage device according to claim 38, wherein the test has one of two results, and the processing step includes the steps of:

processing the initial texture data value according to a first procedure if the test has a first of the two results;

processing the initial texture data value according to a second procedure if the test has a second of the two results.

40. A program storage device according to claim 39, wherein the first procedure is to set the processed texture data value equal to the initial texture data value.

41. A program storage device according to claim 39, wherein the second procedure is to reset the initial texture value to a preset constant value to obtain the processed texture data value.

42. A program storage device according to claim 38, wherein the performing step includes the step of comparing the value of a pre-identified parameter with a predetermined reference value.

43. A graphics adapter board, comprising:

a memory for containing texture data values;

a texture memory fetch circuit for fetching initial texture data values including more than one component from the memory;

a texture filter circuit for filtering texture values; and

an alpha discriminator unit formed for processing the texture data values fetched from the memory, and including

i) a determination circuit to determine whether a discrimination procedure is enabled or not enabled,

ii) a test circuit to perform a preset test on a component of the texture data value not representing color or distance if the discrimination procedure is enabled,

iii) a processing circuit to process the texture data values fetched from the memory according to the results of the test to produce processed texture data values, and

iv) an output to pass the texture data values fetched from the memory to the texture filter circuit if the discrimination procedure is not enabled, and to pass the processed texture data values to the texture filter circuit if the discrimination procedure is enabled.

44. A graphics adapter board according to claim 43, wherein the test has one of two results, and the processing circuit includes:

a first subcircuit for processing the initial texture data value according to a first procedure if the test has a first of the two results; and

a second subcircuit for processing the initial texture data value according to a second procedure if the test has a second of the two results.

45. A graphics adapter board according to claim 43, wherein the test circuit includes means for performing a plurality of different types of tests.

46. A graphics adapter board according to claim 43, wherein the texture values fetched from the memory have a predetermined number of component bits, and the processing circuit includes:

means for holding a state variable identifying a subset of said number of component bits; and

means for processing the subset of said number of component bits according to the results of the tests.