In article <slr### [at] fwicom>,
 Ron Parker <ron### [at] povrayorg> wrote:

> It's handled correctly except for the very rare case where a ray enters
> the water object without leaving the glass object.  If your surfaces are
> close enough together, that almost never happens and AA will fix it if it
> does.

You mean where it just skirts the edge of the water object where it 
overlaps but doesn't touch the inner surface of the glass?


> POV keeps a list of all interiors it's inside, and when it hits another face
> that has the same interior, it removes that interior from the list.  If it
> wasn't the last interior, though, the IOR doesn't change.  That effectively
> makes the glass faces that are inside the water "disappear" from the point
> of view of refraction/TIR, though of course any textures will still be 
> computed.

I see...I think. ;-)
Seems slightly similar to my immersion CSG, only ignoring the ior 
instead of removing the entire surface, and quite a bit more general. 
I'll just have to try to implement it for my own tracer, then I'll 
understand it completely.

-- 
Christopher James Huff <chr### [at] maccom>
POV-Ray TAG e-mail: chr### [at] tagpovrayorg
TAG web site: http://tag.povray.org/

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