Slime wrote:
> 
> Sure, you can go ahead and store the information that "a ray from this point
> hit the isosurface at this point", but the chances of another ray ever
> hitting that same point from the same direction are extremely tiny. Even if
> you did encounter another ray that passed through that point, you'd still
> have to test if it hits the isosurface before it reaches that point.
> 
> Remember, we're not dealing with pixels, we're dealing with an infinite
> number of points in three dimensional space.

It's not that hopeless, you could store all function values evaluated and
use them later for new rays, together with the known max_gradient you can
reduce the number of necessary new function evaluations this way, but you
would have to design efficient methods and data structures for accessing
the stored values and the memory requirements can be enormous.

Christoph

-- 
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