Le 21.09.2007 15:18, Bruno Cabasson nous fit lire :
> I take the risk of appearing stupid, but is it possible to make the
> assumption that if a ray hits an object, the rays next to it (next pixel
> for example, or the next ray shot, or so ...) have a high probability to
> hit the same object, thus avoiding useless tree-traversal and intersection
> test? Would it be costful: if the test fails, then we go on with the normal
> traversal with little overhead, and if success, we save a non neglectable
> time?

That would be fine for a scanline renderer (excepted that I agree
with Warp on missing new intermediate objects), but that fail badly
for a raytracing renderer like povray: what about new rays created
for reflection & refraction ? Multiple reflections ? (just make a
nice pyramid of 10 reflective spheres, with some environment...like
a christmas tree...)

Whatever the solution for these issues, it might end up more
complexe and cpu-costly than the presentation of the idea. (you can
cache based on direction and origin of the ray, but that need to
define "near" for a 6 floating points arrays... and a criteria for
removing entries from the cache... searching the cache... cache
management could be more costly than the direct traversal of
bounding boxes...)

And I agree with Tom York too.

-- 
The superior man understands what is right;
the inferior man understands what will sell.
-- Confucius

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