In article <40345e27@news.povray.org>,
 "Dan P" <dan### [at] yahoocom> wrote:

> Hey, I just saw this commercial where a human body had an ior and I figured
> it must have been a patch. Can you add ior to patches when the inside is not
> well defined?

Using ior only requires that the shape be closed and that it has a 
"clean" interior. When doing refracted rays, POV keeps track of 
insideness by counting surfaces hit...it enters a sphere the first time 
it hits it, and leaves it the second time. A mesh sphere will work 
properly. A mesh sphere with holes in it, or with a stray triangle stuck 
in the middle, will not render properly, but this is practically 
impossible to test, so POV doesn't even try to detect it.

You can't bend a single patch into a shape that's useful for refraction, 
but you can construct a shape out of patches that will render properly 
with refraction. It won't work properly with some CSG operations, though.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/

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