System, method and article of manufacture for shadow mapping

• US 6,690,372 B2
• Filed: 12/05/2000
• Issued: 02/10/2004
• Est. Priority Date: 05/31/2000
• Status: Expired due to Term

• Current Assignee: NVIDIA Corporation
• Original Assignee: NVIDIA Corporation
• Inventors: Donovan, Walter E., Peng, Liang
• Primary Examiner(s): Jankus, Almis R.
• Application Number:
  US09/730,639
• Publication Number:
  US 20020018063A1
• Time in Patent Office: 1,162 Days
• Field of Search: 345/419, 345/420, 345/426, 345/582, 345/589
• US Class Current: 345/426
• CPC Class Codes: G06T 15/50 Lighting effects
• CPC Class Codes: G06T 15/60 Shadow generation
• CPC Class Codes: G06T 15/80 Shading

Abstract

A system, method and article of manufacture are provided for shadow mapping while rendering a primitive in a graphics pipeline. Initially, an offset operation is performed in order to generate a depth value while rendering a primitive. Further, a value of a slope associated with an edge of the primitive is identified. Thereafter, the depth value is conditionally clamped based on the value of the slope.

Claims

1. A method for performing shading calculations in a graphics pipeline, comprising:

performing a first shading calculation in order to generate output;

saving the output; and

performing a second shading calculation using the output in order to generate further output;

wherein the first and second shading calculations together include a plurality of decoupled variables.

2. The method as recited in claim 1 wherein the first and second shading calculations together include a diffuse color variable, a specular color variable, and an ambient color variable.

3. The method as recited in claim 1, wherein at least one of the first and second shading calculations includes a diffuse color variable.

4. The method as recited in claim 1, wherein at least one of the first and second shading calculations includes a specular color variable.

5. The method as recited in claim 1, wherein at least one of the first and second shading calculations includes an ambient color variable.

6. The method as recited in claim 1, wherein the variables are selected from the group consisting of a diffuse color variable, a specular color variable, and an ambient color variable.

7. A method for performing shading calculations in a graphics pipeline, comprising:

performing a first shading calculation in order to generate output;

saving the output; and

performing a second shading calculation using the output in order to generate further output;

wherein the first shading calculation includes [((1−

s))*(Color_diff+Color_spec)]for generating an output A, and the second shading calculation includes [Color_amb+A], where s is a shadow variable, Color_diff is a diffuse color variable Color_spec is a specular color variable, and Color_amb is an ambient color variable.

8. A method for performing shading calculations in a graphics pipeline, comprising:

performing a first shading calculation in order to generate output;

saving the output; and

performing a second shading calculation using the output in order to generate further output;

wherein the first shading calculation includes [(1−

s)*(Color_diff+Color_spec)]for generating an output A, and the second shading calculation includes [A*Texture_det+(1−

s)* Color_spec], where s is a shadow variable Color_duff is a diffuse color variable, Color_spec is a specular color variable, Color_amb is an ambient color variable, and Texture_det is a detail texture variable.

9. A method for performing shading calculations in a graphics pipeline, comprising:

performing a first shading calculation in order to generate output;

saving the output; and

performing a second shading calculation using the output in order to generate further output;

wherein die first and second shading calculations together include a diffuse color variable, a specular color variable, and an ambient color variable;

wherein the variables are decoupled.

10. A method for performing shading calculations in a graphics pipeline, comprising:

performing a first shading calculation in order to generate output;

saving the output; and

performing a second shading calculation using the output in order to generate further output;

wherein the method is carried out with a system comprising;

(a) a shading module for performing the first shading calculation in order to generate the output;

(b) a texture look-up module coupled to the shading module for retrieving texture

information using texture coordinates associated with the output;

(c) a feedback loop coupled between an input and an output of the shading module for performing the second shading calculation using the texture information from the texture look-up module in order to generate further output; and

(d) a combiner module coupled to the output of the shading module for combining the output generated by the shading module.

11. A computer program embodied on a computer readable medium for performing shading calculations in a graphics pipeline, comprising:

(a) a code segment for performing a first shading calculation in order to generate output;

(b) a code segment for saving the output; and

(c) a code segment for performing a second shading calculation using the output in order to generate further output;

wherein the first and second shading calculations together include a plurality of decoupled variables.

12. The computer program as recited in claim 11, wherein the first and second shading calculations together include a diffuse color variable, a specular color variable, and an ambient color variable.

13. The computer program as recited in claim 11, wherein at least one of the first and second shading calculations includes a diffuse color variable.

14. The computer program as recited in claim 11, wherein at least one of the first and second shading calculations includes a specular color variable.

15. The computer program as recited in claim 11, wherein at least one of the first and second shading calculations includes an ambient color variable.

16. The computer program as recited in claim 11, wherein the variables are selected from the group consisting of a diffuse color variable, a specular color variable, and an ambient color variable.

17. A computer program embodied on a computer readable medium for performing shading calculations in a graphics pipeline, comprising:

a code segment for performing a first shading calculation in order to generate output;

a code segment for saving the output; and

a code segment for performing a second shading calculation using the output in order to generate further output;

wherein the first shading calculation includes [(1−

s)*(Color_diff+Color_spec)]for generating an output A, and the second shading calculation includes [Color_amb+A], where s is a shadow variable, Color_diff is a diffuse color variable, Color_spec is a specular color variable, and Color_amb is an ambient color variable.

18. A computer program embodied on a computer readable medium for performing shading calculations in a graphics pipeline, comprising:

a code segment for performing a first shading calculation in order to generate output;

a code segment for saving the output; and

a code segment for performing a second shading calculation using the output in order to generate further output;

wherein the first shading calculation includes [((1−

s)* Color_diff)+Color_amb]for generating an output A, and the second shading calculation includes [A*Texture_det+((1−

s))* Color_spec], where s is a shadow variable Color_diff is a diffuse color variable, Color spec is a specular color variable Color_amb is an ambient color variable, and Texture_det is a texture detail variable.

19. A computer program embodied on a computer readable medium for performing shading calculations in a graphics pipeline, comprising:

a code segment for performing a first shading calculation in order to generate output;

a code segment for saving the output; and

a code segment for performing a second shading calculation using the output in order to generate further output;

wherein the first and second shading calculations together include a diffuse color variable, a specular color variable, and an ambient color variable;

wherein the variables are decoupled.

20. A computer program embodied on a computer readable medium for performing shading calculations in a graphics pipeline, comprising:

a code segment for performing a first shading calculation in order to generate output;

a code segment for saving the output; and

a code segment for performing a second shading calculation using the output in order to generate further output;

wherein the code segments are carried out with a system comprising;

(a) a shading module for performing the first shading calculation in order to generate the output;

(b) a texture look-up module coupled to the shading module for retrieving texture information using texture coordinates associated with the output;

(c) a feedback loop coupled between an input and an output of the shading module for performing the second shading calculation using the texture information from the texture look-up module in order to generate further output; and

(d) a combiner module coupled to the output of the shading module for combining the output generated by the shading module.

21. A system for performing shading calculations in a graphics pipeline, comprising:

(a) logic for performing a first shading calculation in order to generate output;

(b) logic for saving the output; and

(c) logic for performing a second shading calculation using the output in order to generate further outputs;

wherein the first and second shading calculations together include a plurality of decoupled variables.

22. The system as recited in claim 21, wherein the system includes a shading module for performing the first shading calculation in order to generate the output.

23. The system as recited in claim 22, wherein the system includes a texture look-up module coupled to the shading module for retrieving texture information using texture coordinates associated with the output.

24. The system as recited in claim 23, wherein the system includes a feedback loop coupled between an input and an output of the shading module for performing the second shading calculation using the texture information from the texture look-up module in order to generate further output.

25. The system as recited in claim 24, wherein the system includes a combiner module coupled to the output of the shading module for combining the output generated by the shading module.