Graphics texture mapping

Patent metadata

Field	Value
Publication number	US-11610359-B2
Application number	US-202217647134-A
Country	US
Kind code	B2
Filing date	Jan 5, 2022
Priority date	Jan 6, 2021
Publication date	Mar 21, 2023
Grant date	Mar 21, 2023

Abstract

When performing anisotropic filtering when sampling a texture in a graphics processing system, a number of positions for which to sample the texture along an anisotropy direction is determined. When the determined number of positions for which to sample the texture along the anisotropy direction is a non-integer value that exceeds a lower integer value by more than a threshold amount, samples are taken along the anisotropy direction in the texture for a number of positions corresponding to the next higher multiple of 2 to the determined non-integer number of positions to be sampled. When the determined number of positions for which to sample the texture along the anisotropy direction does not exceed the lower integer value by at least the threshold amount, samples are taken along the anisotropy direction in the texture for a number of positions corresponding to the lower integer value.

First claim

What is claimed is:

1. A method of performing anisotropic filtering when sampling a texture to provide an output sampled texture value for use when rendering an output in a graphics processing system, the method comprising:
when sampling a texture using anisotropic filtering to provide an output sampled texture value for a position in the texture:
determining a number of positions for which to sample the texture along an anisotropy direction along which samples will be taken in the texture; and
when the determined number of positions for which to sample the texture along an anisotropy direction along which samples will be taken in the texture is a non-integer value that exceeds a lower integer value by more than a threshold amount, taking samples along the anisotropy direction in the texture for a number of positions corresponding to the next higher multiple of 2 to the determined non-integer number of positions to be sampled;
when the determined number of positions for which to sample the texture along the anisotropy direction along which samples will be taken in the texture does not exceed the lower integer value by at least the threshold amount, taking a sample or samples along the anisotropy direction in the texture for a number of positions corresponding to the lower integer value;
the method further comprising:
using the sample or samples taken along the anisotropy direction in the texture to provide an output sampled texture value for use for the position in the texture that is being sampled.

2. The method of claim 1 , wherein the lower integer value is 1 where the non-integer number of positions to be sampled is between 1 and 2, and is the next lower multiple of 2 where the non-integer number of positions to be sampled is greater than 2.

3. The method of claim 1 , wherein:
determining a number of positions for which to sample the texture along an anisotropy direction along which samples will be taken in the texture comprises:
determining an initial number of positions for which to sample the texture along the anisotropy direction;
using a position count threshold to provide a position count threshold adjusted number of positions for which to sample the texture along the anisotropy direction from the determined initial number of positions for which to sample the texture along the anisotropy direction;

and the method comprises:
when the determined position count threshold adjusted number of positions for which to sample the texture along an anisotropy direction along which samples will be taken in the texture is a non-integer value that exceeds a lower integer value by more than a threshold amount, taking samples along the anisotropy direction in the texture for a number of positions corresponding to the next higher multiple of 2 to the determined non-integer number of positions to be sampled;
when the determined position count threshold adjusted number of positions for which to sample the texture along the anisotropy direction along which samples will be taken in the texture does not exceed the lower integer value by at least the threshold amount, taking a sample or samples along the anisotropy direction in the texture for a number of positions corresponding to the lower integer value.

4. The method of claim 3 , wherein:
when the initially determined number of positions to be sampled is less than the position count threshold above a lower integer value, the position count threshold adjusted number of positions to be sampled is set to be the lower integer value; and
when the initially determined number of positions to be sampled exceeds a lower integer value by greater than the position count threshold, then a position count threshold adjusted number of positions to be sampled that is greater than the lower integer value is determined based on the position count threshold.

5. The method of claim 1 , wherein:
taking the samples along the anisotropy direction in the texture for a number of positions corresponding to the next higher multiple of 2 to the determined non-integer number of positions to be sampled; and
using the samples taken along the anisotropy direction in the texture to provide an output sampled texture value for use for the position in the texture that is being sampled, comprises at least one of:
setting the spacing along the anisotropy direction of the positions for which samples are taken in the texture based on the determined non-integer number of positions to be sampled; and
setting the contribution weights for the positions being sampled to the output sampled texture value based on the determined non-integer number of positions to be sampled.

6. The method of claim 5 , comprising:
when the determined non-integer number of positions to be sampled is between 1 and 2:
setting the spacing along the anisotropy direction of the positions for which samples are taken in the texture based on the determined non-integer number of positions to be sampled as follows:

position_spacing
=

2.0
-

(

2.0
⁢

/

⁢
position_count

)

where position_spacing is the spacing along the anisotropy direction of the positions for which samples are taken in the texture; and
position_count is the determined non-integer number of positions to be sampled.

7. The method of claim 1 , wherein:
determining a number of positions for which to sample the texture along an anisotropy direction along which samples will be taken in the texture comprises:
determining a base number of positions for which to sample the texture along the anisotropy direction based on an estimation of an ellipse corresponding to the projection of the sampling point for which the texture is being sampled onto the surface to which the texture is to be applied; and
applying a step length factor to the determined base number of positions for which to sample the texture along the anisotropy direction to provide a step length adjusted number of positions for which to sample the texture along the anisotropy direction, the step length factor being representative of a spacing between adjacent sampling positions along the anisotropy direction in the texture to be used when sampling the texture;

and the method further comprises:
when the determined step length adjusted number of positions for which to sample the texture along an anisotropy direction along which samples will be taken in the texture is a non-integer value that exceeds a lower integer value by more than a threshold amount, taking samples along the anisotropy direction in the texture for a number of positions corresponding to the next higher multiple of 2 to the determined non-integer number of positions to be sampled;
when the determined step length adjusted number of positions for which to sample the texture along the anisotropy direction along which samples will be taken in the texture does not exceed the lower integer value by at least the threshold amount, taking a sample or samples along the anisotropy direction in the texture for a number of positions corresponding to the lower integer value; and
when taking a sample or samples along the anisotropy direction in the texture, spacing each position for which a sample is being taken from any adjacent position for which a sample is being taken along the anisotropy direction in the texture based on the step length factor

Assignees

• Advanced Risc Mach Ltd

Inventors

• Fielding Edvard
• Castellanos Rodolfo Luis Jalabert

Classifications

• G06T11/10

  Texturing; Colouring; Generation of textures or colours (retouching, inpainting or scratch removal G06T5/77) · CPC title

• G06T7/44

  using image operators, e.g. filters, edge density metrics or local histograms · CPC title

• G06T1/20

  Processor architectures; Processor configuration, e.g. pipelining · CPC title

• G06T2210/36

  Level of detail · CPC title

• G06T15/80

  Shading · CPC title