Deferred shading graphics pipeline processor having advanced features
A deferred shading graphics pipeline processor and method are provided encompassing numerous substructures. Embodiments of the processor and method may include one or more of deferred shading, a tiled frame buffer, and multiple?stage hidden surface removal processing. In the deferred shading graphics pipeline, hidden surface removal is completed before pixel coloring is done. The pipeline processor comprises a command fetch and decode unit, a geometry unit, a mode extraction unit, a sort unit, a setup unit, a cull unit, a mode injection unit, a fragment unit, a texture unit, a Phong lighting unit, a pixel unit, and a backend unit.
1. A method for rendering a graphics image, said method comprising:
performing a fragment operation on a fragment on a per-pixel basis;
performing a fragment operation on said fragment on a per-sample basis;
determining if a pixel corresponding to the fragment is visible on a screen without updating a color buffer;
programmatically selecting whether to perform a stencil test on a per-pixel or a per-sample basis;
rendering the pixel in response to a positive determination; wherein
between said steps, the following step is performed: performing said stencil test on said selected basis.
2. The method of claim 1 , wherein said step of performing on a per-pixel basis comprises performing one of the following fragment operations on a per-pixel basis scissor test, stipple test, alpha test, color test.
3. The method of claim 1 , wherein said step of performing on a per-sample basis comprises performing one of the following fragment operations on a per-sample basis: Z test, blending, dithering.
4. A method for rendering a graphics image, said method comprising:
performing a fragment operation on a fragment on a per-pixel basis;
performing a fragment operation on said fragment on a per-sample basis;
determining if a pixel corresponding to the fragment is visible on a screen without updating a color buffer;
wherein said step of performing on a per-sample basis comprises programmatically selecting a set of subdivisions of a pixel as samples for use in said fragment operation on a per-sample basis, and wherein said method further comprises then programmatically selecting a different set of subdivisions of a pixel as samples for use in a second fragment operation on a per-sample basis; and then performing said second fragment operation on a fragment on a per-sample basis, using said programmatically selected samples.
5. A method for rendering a graphics image, said method comprising:
performing a fragment operation on a fragment on a per-pixel basis;
performing a fragment operation on said fragment on a per-sample basis;
determining if a pixel corresponding to the fragment is visible on a screen without updating a color buffer;
wherein said step of performing on a per-sample basis comprises programmatically selecting a set of subdivisions of a pixel as samples for use in said fragment operation on a per-sample basis; programmatically assigning different weights to two samples in said set; and performing said fragment operation on said fragment on a per-sample basis, using said programmatically selected and differently weighted samples.
6. A computer-readable medium for data storage wherein is located a computer program for causing a graphics-rendering system to render an image by the following method:
performing a fragment operation on a fragment on a per-pixel basis;
performing a fragment operation on said fragment on a per-sample basis;
determining if a pixel corresponding to the fragment is visible on a screen without updating a color buffer;
programmatically selecting whether to perform a stencil test on a per-pixel or a per-sample basis;
rendering the pixel in response to a positive determination; wherein
between said steps, the following step is performed: performing said stencil test on said selected basis.
7. A method for rendering a graphics image, said method comprising:
processing a first primitive;
for each sample touched by the first primitive, conservatively determining whether the sample is hidden, said determination at least partially based on a state variable;
delaying a color computation for said sample until after determining whether the sample is hidden;
rendering each non-hidden sample;
storing a z-coordinate for said sample;
storing primitive color information for said sample;
storing a sample state bit; wherein
said operation of conservatively determining whether the sample is hidden employs at least one of said z-coordinate, primitive color information, and sample state bit.
8. The method of claim 7 , wherein the state variable is the outcome of a depth test.
9. The method of claim 7 , wherein the sate variable is the outcome of an alpha test.
10. The method of claim 7 , further comprising:
processing a second primitive;
for each sample touched by the second primitive, conservatively determining whether the sample is hidden, said determination at least partially based on a state variable; and
delaying a color computation for said sample until after determining whether the sample is hidden;
displaying each sample not determined to be hidden; wherein
said first and second primitives are processed in time order.