Ray tracing scenes is accomplished using a plurality of intersection testing resources coupled with a plurality of shading resources, communicative in the aggregate through links/queues. A queue from testing to shading comprises respective ray/primitive intersection indications, comprising a ray identifier. A queue from shading to testing comprises identifiers of new rays to be tested, wherein data defining the rays is separately stored in memories distributed among the intersection testing resources. Ray definition data can be retained in distributed memories until rays complete intersection testing, and be selected for testing multiple times based on ray identifier. A structure of acceleration shapes can be used. Packets of ray identifiers and shape data can be passed among the intersection testing resources, and each resource can test rays identified in the packet, and for which definition data is present in its memory. Test results for acceleration shapes are used to collect rays against acceleration shapes, and closest detection ray/primitive intersections are indicated by sending ray identifiers to shading resources.