Intersection testing in a ray tracing system

An intersection testing module for use in a ray tracing system, configured to perform intersection testing for a ray with respect to a set of two or more primitives, each primitive being defined by an ordered set of edges, each edge being defined by a respective pair of vertices, the intersection testing module being configured to:

• determine a set of distinct edges for the set of primitives, each distinct edge being part of at least one primitive of the set of primitives and being defined by a different pair of vertices to the other distinct edges in the set, wherein every edge in the ordered sets of edges that define the set of primitives is represented by a distinct edge of the set of distinct edges;
• for each distinct edge in the set of distinct edges, perform an edge test to determine which side of the distinct edge the ray passes on;
• and
• for each primitive in the set of primitives, use a result of the edge test for each distinct edge that defines that primitive to determine whether or not the ray intersects that primitive.

A non-transitory computer readable storage medium having stored thereon an integrated circuit definition dataset that, when processed in an integrated circuit manufacturing system, configures the integrated circuit manufacturing system to manufacture an intersection testing module, for use in a ray tracing system, configured to perform intersection testing for a ray with respect to a set of two or more primitives, each primitive being defined by an ordered set of edges, each edge being defined by a respective pair of vertices, the intersection testing module being configured to:

• determine a set of distinct edges for the set of primitives, each distinct edge being part of at least one primitive of the set of primitives and being defined by a different pair of vertices to the other distinct edges in the set, wherein every edge in the ordered sets of edges that define the set of primitives is represented by a distinct edge of the set of distinct edges;
• for each distinct edge in the set of distinct edges, perform an edge test to determine which side of the distinct edge the ray passes on;
• and
• for each primitive in the set of primitives, use a result of the edge test for each distinct edge that defines that primitive to determine whether or not the ray intersects that primitive.