Method and apparatus for providing logical combination of N alpha operations within a graphics system

• US 7,061,502 B1
• Filed: 11/28/2000
• Issued: 06/13/2006
• Est. Priority Date: 08/23/2000
• Status: Expired due to Term

• Current Assignee: Nintendo Company Limited
• Original Assignee: Nintendo Company Limited
• Inventors: Law, Patrick Y., Yasumoto, Yoshitaka
• Primary Examiner(s): Bella, Matthew C.
• Assistant Examiner(s): Tran, Tam
• Application Number:
  US09/726,212
• Time in Patent Office: 2,023 Days
• Field of Search: 345/589, 345/591, 345/592, 345/593
• US Class Current: 345/592
• CPC Class Codes: G06T 15/02 Non-photorealistic rendering
• CPC Class Codes: G06T 15/503 Blending, e.g. for anti-aliasing

Abstract

A graphics system including a custom graphics and audio processor produces exciting 2D and 3D graphics and surround sound. The system includes a graphics and audio processor including a 3D graphics pipeline and an audio digital signal processor. Logical combination of N alpha compares can be used to provide a wide range of imaging effects including but not limited to cartoon outlining.

Claims

1. A method of generating a graphics image comprising:

(a) generating information representing a surface to be imaged, said information including alpha transparency/opacity information;

(b) performing, at least in part within a recirculating, hardware-based graphics generator, plural alpha comparisons on said alpha information to provide corresponding plural alpha comparison results;

(c) logically combining said plural alpha comparison results; and

(d) rendering said graphics image based at least in part on said logical combination,

wherein said steps (b) and (c) use said recirculating, hardware-based graphics generator to process a programmable alpha tree by providing N logical alpha operations on M alpha inputs, M and N being any integers, M>

1, N>

1.

2. The method of claim 1 wherein said rendering step includes selecting whether or not to kill a pixel based on said logical combination.

3. The method of claim 1 wherein said performing step is performed using a recirculating shader.

4. The method of claim 1 wherein both said performing and said logically combining steps are performed at least in part by hardware.

5. The method of claim 1 wherein said rendering step includes selectively determining whether to blend a cartoon outline color based on said logical combination.

6. The method of claim 1 wherein said steps (b) and (c) implement an absolute value function.

7. The method of claim 1 wherein said plural alpha comparisons include any selected ones of the following:

always,

never,

not equal,

equal,

less than,

greater than or equal,

less than or equal,

greater than.

8. The method of claim 1 wherein said logical combining includes AND, OR, XOR, XNOR.

9. In a home video game system or low cost personal computer graphics card, a hardware-based transparency processor including:

an alpha combiner stage that combines at least first and second alpha input values to generate an alpha result;

an alpha comparator/tester that compares or tests the alpha result; and

a recirculator at least in part responsive to said alpha comparator/tester, said recirculator selectively recirculating said alpha result as at least one of said alpha input values,

whereby said transparency processor processes programmable, arbitrarily complex alpha trees;

wherein said alpha trees have arbitrary complexity comprising N logical operations on M alpha inputs, M and N being any integers, M>

1, N>

1.

10. The transparency processor of claim 9 wherein said recirculator selectively recirculates said alpha result conditioned on said alpha comparison or test said alpha comparator/tester performs on said alpha result.