1. Computer readable media storing computer readable instructions for implementing transmission of ray data generated during ray-tracing based rendering, the method comprising: determining a plurality of rays to emit for intersecting testing in a 3-D scene, each ray having an origin and a direction, wherein one or more attributes shared among the plurality of rays are represented as shared ray data; transmitting the shared ray data and other ray data that, with the shared ray data, is sufficient to construct the respective origin and direction of each ray of the first plurality; receiving, at an intersection testing resource, the shared ray data and other ray data; interpreting the shared ray data to identify the one or more shared attributes for the plurality of rays; using the other ray data and the one or more shared attributes to determine an origin and a direction for each ray of the plurality; and using the determined origins and directions of the rays to define respective rays of the plurality for intersection testing.