clipka <ano### [at] anonymousorg> wrote:

> Because then POV-Ray has to shoot secondary rays (for shadow tests, or
> reflections and/or refractions depending on material), and decide
> whether or not to consider that other surface for this purpose: Is it
> /genuinely/ coincident or just extremely close?
>
> That's where the true can of worms is opened.

Well, yes, I didn't think that there wouldn't be a string of complications in
the ideal implementation - but a simple "if a ray from the camera intersects
only one object then assign the designated material, if it intersects both
objects, then assign the designated third material (which may be the same as
either of the previous)" would at least be useful for highlighting some overlaps
in CSG, and could give rise to some hard-to-envision effects that might make a
useful artistic tool.

And I suppose that part of the implementation could be an option Epsilon value
to override the usual 1E-06 distance...

Like I said, it was just something that popped into the noggin before I even
really woke up.

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