Shadow softening graphics processing unit and method
AssigneeNVIDIA Corporation
InventorG. Evan Hart
Life of this patent
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Abstract
A shadow softening GPU and method. One embodiment of the GPU is configured to render a shadow cast by a surface occluding a light source and includes: (1) a fetching circuit operable to retrieve a depth value from a texture associated with the surface and a depth comparison result in a single fetch operation, and (2) a shadow softening circuit configured to respectively employ the depth comparison result and the depth value to identify the surface as a blocker and attenuate the light source for a pixel.
Claims20
A graphics processing unit (GPU) configured to render a shadow cast by a surface occluding a light source, comprising:
- a fetching circuit operable to retrieve a depth value from a texture associated with said surface and a depth comparison result in a single fetch operation;
- and
- a shadow softening circuit configured to respectively employ said depth comparison result and said depth value to identify said surface as a blocker and attenuate said light source for a pixel.
A method of shadow softening a pixel in a scene with respect to a light source, comprising:
- rendering a light-space depth map for said scene with respect to said light source;
- comparing a sample depth from said light-space depth map to a screen-space depth of said pixel transformed into light space;
- fetching said sample depth from a texture held in a memory and a result of said comparing in a single fetch operation;
- and
- employing said result and said sample depth in attenuating said light source with respect to said pixel.
A graphics processing subsystem configured to shade a pixel, comprising:
- a memory configured to store a shadow map texture containing texels characterizing potentially occluding surfaces with respect to a light source, said texels configured to contain a light-space depth value;
- and
- a graphics processing unit (GPU) configured to take sample texels of said shadow map texture about said pixel and having:
- a fetching circuit operable to retrieve said light-space depth value from one of said sample texels and a depth comparison result in a single fetch operation, and
- a shadow softening circuit configured to respectively employ said depth comparison result and said light-space depth value of each of said sample texels to identify said potentially occluding surfaces as blockers and attenuate said light source for said pixel.
Dependencies are inferred from the claim text.