Imagination Technologies Limited

Peter Smith-Lacey

Simon James Fenney

Gregory Clark

Rostam King

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

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 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 computer-implemented method for compressing, an input group of m data values compresses the two least significant bits of each of the data values by mapping the two least significant bits of each of the data values in the input group of m data values collectively onto an m-bit encoding and storing the m-bit encoding, the m-bit encoding being selected from 2m-bit encodings, the 2m-bit encodings comprising a first group of encodings comprising (2−4) m-bit encodings and a second group of encodings comprising four m-bit encodings, wherein if the selected encoding is an encoding from the first group of encodings then the selected encoding represents the two least significant bits for a representative group of m data values in which the second least significant bit of each of the data values is the same as a respective bit of the m-bit encoding, and wherein if the selected encoding is an encoding from the second group of encodings then the selected encoding represents the two least significant bits for a representative group of m data values in which the two least significant bits for each of the data values in the representative group are equal to the two least significant bits of the other data values in the representative group.

Data compression and decompression

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

A method and an intersection testing module in a ray tracing system for performing intersection testing for a ray with respect to a plurality of convex polygons, each of which is defined by an ordered set of vertices. The vertices of the convex polygons are projected onto a pair of axes orthogonal to the ray direction. For each edge of a convex polygon defined by two of the projected vertices, a signed parameter is determined, wherein the sign of the signed parameter is indicative of which side of the edge the ray passes on. If the ray is determined to intersect a point on the edge then the sign of the signed parameter is determined using a module which is configured to: take as inputs, indications which classify each of p, q, pand qcoordinates as negative, zero or positive, and output, for valid combinations of classifications of the p, q, pand qcoordinates, an indication of the sign of the signed parameter. It is then determined whether the ray intersects the convex polygon based on the signs of the signed parameters determined for the edges of the convex polygon.

Intersection testing in a ray tracing system using convex polygon edge signed parameters

Intersection testing is performed for a ray with respect to a plurality of convex polygons, each of which is defined by an ordered set of vertices, wherein a shared vertex is used to define at least two of the convex polygons. The vertices of the convex polygons are projected onto a pair of axes orthogonal to the ray direction. A vertex ordering scheme defines an ordering of the projected vertices which is independent of the ordering of the vertices in the ordered sets. For each of the convex polygons, for each edge of the convex polygon defined by two of the projected vertices, a parameter indicative of which side of the edge the ray passes on is determined, wherein if the ray is determined to intersect a point on the edge then the parameter is determined based upon whether the ordering of the projected vertices defining the edge matches the ordering of the vertices in the ordered set of vertices defining the convex polygon. Whether the ray intersects the convex polygon is determined based on the parameters determined for the edges of the convex polygon.

Intersection testing in a ray tracing system using convex polygon edge parameters

A method and an intersection testing module for performing intersection testing of a ray with a box in a ray tracing system. The ray and the box are defined in a 3D space using a space-coordinate system, and the ray is defined with a ray origin and a ray direction. A ray-coordinate system is used to perform intersection testing, wherein the ray-coordinate system has an origin at the ray origin, and the ray-coordinate system has three basis vectors. A first of the basis vectors is aligned with the ray direction. A second and a third of the basis vectors: (i) are both orthogonal to the first basis vector, (ii) are not parallel with each other, and (iii) have a zero as one component when expressed in the space-coordinate system. A result of performing the intersection testing is outputted for use by the ray tracing system.

Intersection testing in a ray tracing system using ray coordinate system basis vectors

A method and an intersection testing module for performing intersection testing of a ray with a convex polygon in a ray tracing system. The ray and the convex polygon are defined in a 3D space using a space-coordinate system. The ray is defined with a ray origin and a ray direction. A ray-coordinate system is used to perform intersection testing, wherein the ray-coordinate system has an origin at the ray origin, and wherein the ray-coordinate system has three basis vectors. A first of the basis vectors is aligned with the ray direction. A second and a third of the basis vectors: (i) are both orthogonal to the first basis vector, (ii) are not parallel with each other, and (iii) have a zero as one component when expressed in the space-coordinate system. A result of performing the intersection testing is outputted for use by the ray tracing system.

Intersection testing in a ray tracing system using a ray coordinate system

A method and an intersection testing module in a ray tracing system for performing intersection testing for a ray with respect to a plurality of convex polygons, each of which is defined by an ordered set of vertices, wherein at least one of the vertices is a shared vertex which is used to define at least two of the convex polygons. The vertices of the convex polygons are projected onto a pair of axes orthogonal to the ray direction. A vertex ordering scheme defines an ordering of the projected vertices which is independent of the ordering of the vertices in the ordered sets. For each of the convex polygons, for each edge of the convex polygon defined by two of the projected vertices, a parameter indicative of which side of the edge the ray passes on is determined, wherein if the ray is determined to intersect a point on the edge then the parameter is determined based upon whether the ordering of the projected vertices defining the edge matches the ordering of the vertices in the ordered set of vertices defining the convex polygon. Whether the ray intersects the convex polygon is determined based on the parameters determined for the edges of the convex polygon.

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Peter Smith-Lacey