[tehsauce]

There are two-pass approaches that do this, such as photon mapping. In the first stage, light is emitted from light sources and allowed to to scatter throughout the scene, and each "hit" of a photon on a medium is stored in a large data structure. Then in the second pass rays are traced out from the camera, and on each medium the ray intersects, nearby "hits" are used to estimate the light coming from that spot. This produces effects like caustics efficiently.