In article <414da1ca@news.povray.org>, Warp <war### [at] tagpovrayorg> 
wrote:

>   AFAIK triangles do not have an inside (which is why meshes do not work
> in CSG unless a very specialized insideness test (turned on with the
> 'inside_vector' keyword) is used). It may well be a good idea to use
> meshes instead of discs or other solid objects for a particle system.

They do not have an inside. They do have insideness, however. An 
intersection with another object would give nothing, but a ray enters a 
transparent triangle when it hits it, and exits if it hits it again 
(after a reflection, for example). Anything seen through a triangle is 
"inside" it as far as volumetric calculations are concerned.
Obviously, this isn't too useful for triangles...perhaps an additional 
test can be performed to ignore the "volume" of patch objects.

-- 
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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