Imagination Technologies Limited

Simon James Fenney

Peter Malcolm Lacey

Gregory Clark

Rostam King

Linling Zhang

Peter Smith-Lacey

Michael Worcester

Stuart Smith

Vasiliki Simaiaki

Xile Yang

John William Howson

Jeff Bond

Ilaria Martinelli

Ian King

Tobias Hector

Piers Barber

Luke Tilman Peterson

Martin Ashton

Jonathan Mark Redshaw

Clifford Gibson

Hossein Yassaie

Alan Vines

Peter David Leaback

Mark Edward Dunn

Alper Ozkan

John Russell

Greg Clark

Ian James Overliese

Paolo Giuseppe Fazzini

Joseph John Davison

Jeffery Thomas Bond

Nico Ritsche

Selina Hopton

Alex Joseph William Walters

Mark Butler

Simon Pearce

Jonathan Alan Redshaw

A method and an intersection testing module for performing intersection testing in a ray tracing system determines a first offset intersection distance which is equal to a sum of an intersection distance at which a ray intersects a first primitive and a first offset which is dependent upon the orientation of the first primitive. A second offset intersection distance is determined which is equal to a sum of an intersection distance at which the ray intersects a second primitive and a second offset which is dependent upon the orientation of the second primitive. The determined first and second offset intersection distances are compared to select the intersection of the ray with one of the first and second primitives.

Intersection testing in a ray tracing system using offset intersection distances

Compressed data is decompressed to determine sub-primitive presence indications in a rendering system. A received compressed block of sub-primitive presence indications is subdivided into a plurality of parent regions, each subdivided into a plurality of child regions. A hierarchical representation of the block of sub-primitive presence indications is provided, wherein: (i) for each parent region whose child regions all have the same presence state, parent-level data is included to represent the presence state of the parent region without child-level data for the child regions within the parent region being included in the hierarchical representation, and (ii) for each parent region whose child regions do not all have the same presence state, child-level data for the child regions within the parent region is included in the hierarchical representation to represent the presence states for the child regions within the parent region. If child-level data is included in the hierarchical representation, child-level data for said one of the parent regions is used to determine one or more sub-primitive presence indications in the parent region. If child-level data is not included in the hierarchical representation, parent-level data is used, without child-level data, to determine one or more sub-primitive presence indications in the parent region.

Compression and decompression of sub-primitive presence indications for use in a rendering system

A method of encoding data values comprises mapping each of a plurality of input values to one of a pre-defined set of codes based on a probability distribution of the input values. In various examples an input value may be mapped to a code having the same bit-length as the input value and in other examples, the code may be longer than the input value. In various examples, the input values may be grouped into data words and may additionally comprise one or more padding bits.

Efficient encoding methods

A method and an intersection testing module for performing intersection testing in a ray tracing system determines that a difference between an intersection distance at which a ray intersects a first primitive and an intersection distance at which the ray intersects a second primitive satisfies a comparison condition with respect to a threshold. It is determined that the orientations of the first and second primitives are different. The intersection of the ray with one of the first and second primitives is selected on the basis that the one of the first and second primitives has a particular orientation.

Intersection testing in a ray tracing system

A method of converting 10-bit pixel data (e.g. 10:10:10:2 data) into 8-bit pixel data involves converting the 10-bit values to 7-bits or 8-bits and generating error values for each of the converted values. Two of the 8-bit output channels comprise a combination of a converted 7-bit value and one of the bits from the fourth input channel. A third 8-bit output channel comprises the converted 8-bit value and the fourth 8-bit output channel comprises the error values. In various examples, the bits of the error values may be interleaved when they are packed into the fourth output channel.

Guaranteed data compression

A method and an intersection testing module for performing intersection testing in a ray tracing system determines if a difference between an intersection distance at which a ray intersects a first primitive and an intersection distance at which the ray intersects a second primitive satisfies a comparison condition with respect to a threshold, and if the orientations of the first and second primitives are different. If so the intersection of the ray with the one of the first and second primitives which has a particular orientation is selected.

Intersection testing in a ray tracing system using comparison of intersection distance differences between primitive intersections

A ray tracing system and method for processing data in which a forward transformation indication is received defining a transformation from a first space to a second space. A transformation is performed on input data from the second space to the first space to determine transformed data by performing a reverse translation operation on the input data, wherein the reverse translation operation is the reverse of a translation defined by the forward transformation indication. An inverse linear mapping operation is performed on the result of the reverse translation operation, wherein the inverse linear mapping operation is the inverse of a linear mapping defined by the forward transformation indication. The transformed data is processed in the ray tracing system.

Transformation of data in a ray tracing system

A method and a compression unit are provided for compressing, into a block of compressed data, a block of sub-primitive presence indications for use in a rendering system. The block of sub-primitive presence indications is subdivided into a plurality of parent regions, each of the parent regions being subdivided into a plurality of child regions. A presence state is identified for each of the child regions based on the sub-primitive presence indications in the block of sub-primitive presence indications. A hierarchical representation of the block of sub-primitive presence indications is stored in the block of compressed data. For each of one or more parent regions whose child regions all have the same identified presence state, parent-level data is included in the hierarchical representation to represent the presence state of the parent region without child-level data for the child regions within the parent region being included in the hierarchical representation. For each of one or more parent regions whose child regions do not all have the same identified presence state, child-level data for the child regions within the parent region is included in the hierarchical representation to represent the presence states for the child regions within the parent region.

Implementations of post-tessellation blender hardware perform both domain shading and blending and whilst some vertices may not require blending, all vertices require domain shading. The blender hardware includes a cache and/or a content addressable memory and these data structures are used to reduce duplicate domain shading operations.

Post-tessellation blending in a GPU pipeline

A tessellation method uses both vertex tessellation factors and displacement factors defined for each vertex of a patch, which may be a quad, a triangle or an isoline. The method is implemented in a computer graphics system and involves calculating a vertex tessellation factor for each corner vertex in one or more input patches. Tessellation is then performed on the plurality of input patches using the vertex tessellation factors. The tessellation operation involves adding one or more new vertices and calculating a displacement factor for each newly added vertex. A world space parameter for each vertex is subsequently determined by calculating a target world space parameter for each vertex and then modifying the target world space parameter for a vertex using the displacement factor for that vertex.

Tessellation method using displacement factors

A graphics processing system includes a tiling unit configured to tile a scene into a plurality of tiles. A processing unit identifies tiles of the plurality of tiles that are each associated with at least a predetermined number of primitives. A memory management unit allocates a portion of memory to each of the identified tiles and does not allocate a portion of memory for each of the plurality of tiles that are not identified by the processing unit. A rendering unit renders each of the identified tiles and does not render tiles that are not identified by the processing unit.

Sparse rendering in computer graphics

Methods and intersection testing modules are provided for determining, in a ray tracing system, whether a ray intersects a 3D axis-aligned box representing a volume defined by a front-facing plane and a back-facing plane for each dimension. The front-facing plane of the box which intersects the ray furthest along the ray is identified. It is determined whether the ray intersects the identified front-facing plane at a position that is no further along the ray than positions at which the ray intersects the back-facing planes in a subset of the dimensions, and this determination is used to determine whether the ray intersects the axis-aligned box. The subset of dimensions comprises the two dimensions for which the front-facing plane was not identified, but does not comprise the dimension for which the front-facing plane was identified. It is determined whether the ray intersects the box without performing a test to determine whether the ray intersects the identified front-facing plane at a position that is no further along the ray than a position at which the ray intersects the back-facing plane in the dimension for which the front-facing plane was identified.

Intersection testing in a ray tracing system using three-dimensional axis-aligned box

A hierarchical acceleration structure for use in a ray tracing system. When generating a node for the hierarchical acceleration structure, the primitives in a particular portion of the 3D scene may be alternatively bounded by different shaped volumes. These bounding volumes or 'bounding regions' can be Axis Aligned Bounding Boxes (AABBs), although other bounding volumes can be used. The ray tracing system may use sets of two or more bounding volumes in a 3D scene to bound all the primitives within that portion. The choice of how to create sets of multiple bounding volumes within a portion of the 3D scene may be done by using a binary space partition (BSP). Different sets of bounding regions may present different amounts of surface area for a hypothetical ray entering the portion of the 3D scene dependent upon the expected ray direction or angle.

Method of traversing a hierarchical acceleration structure

A method and an intersection testing module in a ray tracing system for determining whether a ray intersects a three-dimensional axis-aligned box. It is determined whether a first condition is satisfied, wherein the first condition is, or is equivalent to, It is determined whether a second condition is satisfied, wherein the second condition is, or is equivalent to, It is determined whether a third condition is satisfied, wherein the third condition is, or is equivalent to, The determinations of whether the first, second and third conditions are satisfied are used to determine whether the ray intersects the axis-aligned box. C, Cand Care x, y and z components of a position of the centre of the axis-aligned box relative to an origin of the ray, H, Hand Hare half widths of the axis-aligned box in the x, y and z dimensions, and D, Dand Dare x, y and z components of a direction vector of the ray.

Intersection testing in a ray tracing system using axis-aligned box coordinate components

Interpolation logic described herein provides a good approximation to a bicubic interpolation, which is generally smoother than bilinear interpolation, without performing all the calculations normally needed for a bicubic interpolation. This allows an approximation of smooth bicubic interpolation to be performed on devices (e.g. mobile devices) which have limited processing resources. At each of a set of predetermined interpolation positions within an array of data points, a set of predetermined weights represent a bicubic interpolation which can be applied to the data points. For a plurality of the predetermined interpolation positions which surround the sampling position, the corresponding sets of predetermined weights and the data points are used to determine a plurality of surrounding interpolated values which represent results of performing the bicubic interpolation at the surrounding predetermined interpolation positions. A linear interpolation is then performed on the surrounding interpolated values to determine an interpolated value at the sampling position.

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Simon James Fenney