Method and system for implementing graphics control constructs

• US 6,707,462 B1
• Filed: 05/12/2000
• Issued: 03/16/2004
• Est. Priority Date: 05/12/2000
• Status: Expired due to Term

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Peercy, Mark S., Olano, Thomas M., Airey, John M.
• Primary Examiner(s): Cabeca, John
• Assistant Examiner(s): Hailu, Tadesse
• Application Number:
  US09/569,649
• Time in Patent Office: 1,404 Days
• Field of Search: 345/619, 345/625, 345/634, 345/676, 345/682, 345/422, 345/506, 345/419
• US Class Current: 345/619
• CPC Class Codes: G06T 15/40 Hidden part removal

Abstract

One aspect of the invention is a method for implementing a graphics control construct. The method includes the step of assigning by a graphics system interface (15) a value to at least one bit in a stencil buffer (S) in response to a first condition of a first conditional clause in an application program (11). The method also includes the steps of selecting at least a first portion of image data in response to the value, and processing the selected first portion of image data in a frame buffer (70) of a graphics pipeline (17).

Claims

1. A method for implementing a graphics control construct, comprising:

assigning a value to a first bit in a stencil buffer used by a graphics system interface in response to a first condition of a first conditional clause in an application program;

selecting a first portion of image data in response to the value; and

processing the selected first portion of image data in a frame buffer of a graphics pipeline;

assigning a value to a second bit in the stencil buffer in response to a first condition of a second conditional clause in the application program, the second conditional clause nested within the first conditional clause;

selecting a second portion of image data in response to the value assigned to the second bit; and

processing the selected second portion of image data in the frame buffer.

2. The method of claim 1, wherein assigning the value to the first bit includes one of the group consisting of decrementing the value and incrementing the value.

3. The method of claim 1, wherein the first conditional clause is operable to perform the function of one of the group consisting of an if clause, an else clause, a for clause, a while clause, and a do clause.

4. The method of claim 1, wherein selecting the first portion includes utilizing an alpha channel of the graphics pipeline.

5. A method for implementing a graphics control construct, comprising:

assigning a value to at least one bit in a stencil buffer used by a graphics system interface in response to a first condition of a first conditional clause in an application program;

selecting at least a first portion of image data in response to the value;

processing the selected first portion of image data in a frame buffer of a graphics pipeline; and

testing an end condition of the first conditional clause by determining whether one of the group of a minimum value and a maximum value is equal to a known constant.

6. An application for implementing a control construct, comprising:

a computer-readable medium; and

software residing on the computer-readable medium, the software operable to;

assign a value to a first bit in a stencil buffer used by a graphics system interface in response to a first condition of a first conditional clause;

assign a value to a second bit in the stencil buffer in response to a first condition of a second conditional clause nested within the first conditional clause;

select a first portion of image data in response to the value;

cause the selected first portion of image data to be processed in a frame buffer of a graphics pipeline;

select a second portion of image data in response to the value assigned to the second bit; and

cause the selected second portion of image data to be processed in the frame buffer.

7. The application of claim 6, wherein the first conditional clause is operable to perform the function of one of the group consisting of an if clause, an else clause, a for clause, a while clause, and a do clause.

8. The application of claim 6, wherein the software is operable to assign the value by one of the group consisting of decrementing the value and incrementing the value.

9. The application of claim 6, wherein the software is further operable to select utilizing an alpha channel of the graphics pipeline.

10. An application for implementing a control construct, comprising:

a computer-readable medium; and

software residing on the computer-readable medium, the software operable to;

assign a value to at least one bit in a stencil buffer used by a graphics system interface in response to a first condition of a first conditional clause;

select at least a first portion of image data in response to the value; and

cause the selected first portion of image data to be processed in a frame buffer of a graphics pipeline; and

test an end condition of the first conditional clause by determining whether one of the group of a minimum value and a maximum value is equal to a known constant.

11. The application of claim 10, wherein the graphics system interface is operable to perform at least a subset of the functions of those performed by the graphics system interface sold under the trademark OPENGL®

.

12. A system for implementing a control construct, comprising:

a graphics system interface;

a graphics system host coupled to the graphics system interface; and

an application program resident on the host, the application program operable to;

assign a value to a first bit in a stencil buffer used by the graphics system interface in response to a first condition of a first conditional clause and select a first portion of image data in response to the value, cause the selected first portion of image data to be processed in a frame buffer of a graphics pipeline coupled to the host;

assign a value to a second bit in the stencil buffer in response to a first condition of a second conditional clause nested within the first conditional clause and select a second portion of image data in response to the value assigned to the second bit; and

cause the selected second portion of image data to be processed in the frame buffer.

13. The application of claim 12, wherein the first conditional clause is operable to perform the function of one of the group consisting of an if clause, an else clause, a for clause, a while clause, and a do clause.

14. The system of claim 12, wherein the application program is operable to assign the value by one of the group consisting of decrementing the value and incrementing the value.

15. The system of claim 12, wherein the application program is further operable to select utilizing the alpha channel of the graphics pipeline.

16. A system for implementing a control construct, comprising:

a graphics system interface;

a graphics system host coupled to the graphics system interface; and

an application program resident on the host, the application program operable to;

assign a value to at least one bit in a stencil buffer used by the graphics system interface in response to a first condition of a first conditional clause and select at least a first portion of image data in response to the value;

cause the selected first portion of image data to be processed in a frame buffer of a graphics pipeline coupled to the host; and

test an end condition of the first conditional clause by determining whether one of the group of a minimum value and a maximum value is equal to a known constant.

17. The system of claim 16, wherein the graphics system interface is operable to perform at least a subset of the functions of those performed by the graphics system interface sold under the trademark OPENGL®

.