Ray caching for very fast re-rendering

[Sam Lapere]

[Idea from Juan]

When interactively visualising a simulation from the same camera viewpoint, ray-geometry intersections could be cached to allow for very fast HQ simulation playback.

See e.g. http://floyd.lbl.gov/radiance/papers/ewp98.pdf (very old paper, but the proposed ideas are still relevant and could be useful for Brayns)

Excerpt from the paper:

"Rays are computed, cached, and eventually stored to disk using a holodeck data structure -- a spatial grid used to sort rays without regard to sampling density. These rays are reused for subsequent views, which may be refined while the view is stationary.
Each ray intersection distance is recorded along with the floating point color to enhance display processing. This requires a total of 10 bytes per sample in our implementation.
Rays are clustered together into beams for efficient disk access, so no compression or “development” stage is required. "