For ray tracing systems, described methods, media, apparatuses provide for accounting of light energy that will be collected at pixels of a 2-D representation without recursive closure of a tree of ray/primitive intersections, and also provide for adaptivity in ray tracing based on importance indicators of each ray, such as a weight, which may be carried in data structures representative of the rays. Examples of such adaptivity may include determining a number of children to issue for shading an identified intersecting primitive, culling rays, and adding rays to achieve more accurate sampling, if desired. All such adaptivity may be triggered with goal-based indicators, such as a threshold value representative of rendering progress to a time-based goal, such as a frame rate.