Asynchronous and concurrent ray tracing and rasterization rendering processes

Patent metadata

Field	Value
Publication number	US-9607426-B1
Application number	US-201414570314-A
Country	US
Kind code	B1
Filing date	Dec 15, 2014
Priority date	Dec 20, 2013
Publication date	Mar 28, 2017
Grant date	Mar 28, 2017

Abstract

Rendering systems that can use combinations of rasterization rendering processes and ray tracing rendering processes are disclosed. In some implementations, these systems perform a rasterization pass to identify visible surfaces of pixels in an image. Some implementations may begin shading processes for visible surfaces, before the geometry is entirely processed, in which rays are emitted. Rays can be culled at various points during processing, based on determining whether the surface from which the ray was emitted is still visible. Rendering systems may implement rendering effects as disclosed.

First claim

I claim:

1. A machine-implemented method for rasterizing a stream of geometry for a frame of pixels wherein a value of each pixel is defined based on one or more samples for that pixel, the method comprising:
processing at least one element of geometry from the stream and determining a first visible element of geometry at a sample for a pixel in the frame of pixels;
responsive to determining the first visible element of geometry, initiating running of a shader for said first visible element of geometry, comprising emitting a ray to be traced within a 3-D scene in which elements of the geometry are located, the ray associated with the sample; and
processing at least one other element of geometry from the stream and determining a second visible element of geometry at the sample and determining whether the second visible element of geometry is the same element of geometry as the first visible element of geometry, and if so, then continuing to process the ray, and otherwise terminating the processing of the ray.

2. The machine-implemented method of claim 1 , wherein the emitting of the ray comprises producing definition data for the ray and associating status data with the data defining the ray.

3. The machine-implemented method of claim 2 , wherein the status data associated with the ray comprises at least one of an identifier for a currently-visible element of geometry and a depth of a currently-visible element of geometry.

4. The machine-implemented method of claim 2 , wherein the status data associated with the ray comprises an index that is incremented each time a new visible element of geometry is found for the sample with which the ray is associated.

5. The machine-implemented method of claim 1 , further comprising maintaining an index for each sample correlated to a number of times that a currently-visible element of geometry for that sample has been updated.

6. The machine-implemented method of claim 1 , wherein the determining whether the second visible element of geometry for the sample associated with the ray is the same element of geometry as the first visible element of geometry comprises tracking, per element of geometry, which samples are visible for that element of geometry.

7. The machine-implemented method of claim 1 , wherein the determining whether the second visible element of geometry for the sample associated with the ray is the same element of geometry as the first visible element of geometry at that sample when the ray was emitted comprises tracking, per element of geometry, ranges of sample identifiers at which that element of geometry is visible.

8. The machine-implemented method of claim 1 , wherein the determining whether the second visible element of geometry for the sample associated with the ray is the same element of geometry as the first visible element of geometry comprises tracking a range of depths for a portion of pixels, and comparing a distance to an intersection for the ray with the range of depths for the portion of pixels.

9. The machine-implemented method of claim 1 , wherein the determining whether the second visible element of geometry for the sample associated with the ray is the same element of geometry as the first visible element of geometry comprises tracking a group of rays together, and comparing a range of intersection distances for the group of rays with a depth or range of depths for one or more pixels.

10. The machine-implemented method of claim 1 , wherein the determining whether a currently-visible element of geometry for the sample associated with the ray is the same element of geometry that was visible at that sample when the ray was emitted comprises maintaining an index for each sample that correlates to a number of times that the currently-visible surface for that sample has been updated.

11. The machine-implemented method of claim 1 , wherein the determining whether the second visible element of geometry for the sample associated with the ray is the same element of geometry as the first visible element of geometry comprises maintaining an association between an identifier of each sample and an identifier of a currently visible element of geometry at that sample, if any.

12. The machine-implemented method of claim 1 , further comprising maintaining a list of identifiers for elements of geometry, each in association with respective identifiers for each sample at which that element of geometry is visible, and before initiating a portion of computation to process the ray, checking whether an identifier associated with the ray is listed as a visible surface at a sample associated with the ray.

13. The machine-implemented method of claim 12 , wherein the portion of computation comprises executing a shader for shading an intersection identified between the ray and an element of geometry.

14. The machine-implemented method of claim 12 , wherein the portion of computation comprises traversing the ray through at least a portion of a hierarchical acceleration structure.

15. The machine-implemented method of claim 1 , wherein the currently-visible surface determined by the rasterization is a default surface.

16. An apparatus for rasterizing a stream of polygons for a frame of pixels wherein a value of each pixel is defined based on one or more samples for that pixel, comprising:
a rasterization engine configured for identifying pixels of an image, which are overlapped by a polygon from a stream of polygons defining objects located in a 3-D scene;
a shading engine configured to initiate shading of a polygon determined to be visible at a sample of the image being rendered, before the stream of polygons has been completely processed by the rasterization engine, wherein the shading engine is configured to execute instructions that emit rays to be traced in the 3-D scene, each ray associated with a sample and a polygon visible at that sample when that ray was emitted; and
a ray tracing engine that is configured to trace the emitted rays in the 3-D scene, to shade intersections identified for the emitted rays, and to determine, before commencing one or more operations performed during the tracing and shading of each ray, whether the polygon associated with that ray is still the visible surface at the sample associated with the ray, and if so, then to proceed with the one or more operations for that ray, and otherwise to terminate tracing of that ray and shading of intersections.

17. The apparatus of claim 16 ,
wherein a portion of the ray tracing engine configured to shade an intersection between a ray and a polygon is implemented by a computation unit that is programmable with machine executable instructions.

18. The apparatus of claim 17 , wherein the programmable computation unit also implements the shading engine under configuration of machine executable instructions.

19. A graphics processing apparatus, comprising:
a rasterization engine configured to identify pixels of an image, which are overlapped by a polygon from a stream of polygons defining objects located in a 3-D scene;
a ray tracing engine configured to trace rays in the 3-D scene, wherein the ray tracing engine is configured to operate concurrently with the rasterization engine, for shading of pixels of a single 2-D image being rendered from the 3-D scene; and
a ray contribution verification module coupled to receive outputs from ray shaders, each of the outputs associated with a respective pixel of the 2-D image, and to verify that each output pertains to a surface that contributes to a final shading of the pixel associated with that

Assignees

• Imagination Tech Ltd
• Imagination Tech Ltd

Inventors

• Peterson Luke T

Classifications

• G06T15/06 Primary

  Ray-tracing · CPC title

• G06T15/80

  Shading · CPC title

• G09G5/363

  Graphics controllers · CPC title

• G06F9/44

  Arrangements for executing specific programs · CPC title

• G06T15/005

  General purpose rendering architectures · CPC title