In article <418afe1a$1@news.povray.org>, "Slime" <fak### [at] emailaddress> 
wrote:

> > As counter-intuitive ideas go, put that near the top of the list.  How
> > does it work if a reflected ray never hits?
> 
> Then it takes the color of the sky_sphere as though it were centered at the
> origin of the reflected ray.

Actually, centered at < 0, 0, 0>, no matter what the origin of the ray. 
Otherwise reflections and refractions would look really, really weird. 
(Consider an image of smooth water...two nearby points on the water 
would see totally different skies. And the sky seen through a window 
would be completely different from that seen directly, because the rays 
would originate from the glass, not the camera.)

And there's not really any surface, it's just a pigment determining the 
background color. That's why you can't use normal, finish, or interior. 
(Though you could define the normal as the mirror of the ray direction, 
POV-Ray didn't last I checked.)

Basically, it takes the normalized direction of the ray as the pigment 
evaluation point.

-- 
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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