These are the sunglasses referred to in my post in P.G.

I'm trying to get the lens material looking right.

In the detail view you'll note the extra reflections of the lines of the 
ball are back reflected and you end up with an annoying pattern being 
visible through the glass.

(Also, the glasses feel like they're too big to me. Agree?)

Just to settle your minds, if you're wondering what brand of glasses 
netballs prefer .. the detail of the side will show a "POV-Ray Ban" logo :)

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> Rick Measham wrote:
> 
>> In the detail view you'll note the extra reflections of the lines of 
>> the ball are back reflected and you end up with an annoying pattern 
>> being visible through the glass.

Darren New wrote:
> Maybe it's because both the front and back surface of the glass is 
> mirrored, and the light is reflecting back and forth?

It would be. I'm just past considering myself a newbie, but not at the 
point where I know how to apply a different surface to the back of an 
object. (Lens is sphere - smaller_sphere)

A pointer would be great at this point.

Cheers!
Rick

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> > Maybe it's because both the front and back surface of the glass is
> > mirrored, and the light is reflecting back and forth?
>
> It would be. I'm just past considering myself a newbie, but not at the
> point where I know how to apply a different surface to the back of an
> object. (Lens is sphere - smaller_sphere)

I think there are two issues here:
 - internal reflections bouncing back and forth within the lens are
undesired
 - you want the lens to look different depending on whether you look through
the front or the back

To fix the first problem, simply specify an interior_texture on the whole
object which has no reflection:

interior_texture {
pigment {rgbt 1}
}

Then any rays which pass through the object will only be affected by the
texture information on the outer surface; when they hit the inner surface on
the way out, they'll just pass right through.

The second thing, if I understand it right, can be taken care of by using a
different texture on each sphere. On the "outer" sphere, which creates the
surface that we're currently looking through, make your dark-sunglass
texture which has very little transparency and lots of reflection. On the
"inner" sphere, the one being cut out of the outer one, apply a
mostly-transparent texture with reflection. Then the appearance of the lens
will change depending on which way you look through it.

So you'll end up with this:

difference {
sphere {...
texture {dark_texture}
}
sphere {...
texture {clear_texture}
}
interior_texture {
pigment {rgbt 1}
}
}

 - Slime
 [ http://www.slimeland.com/ ]

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news:420F0060.8060307@nomail...
> > Rick Measham wrote:
> >
> It would be. I'm just past considering myself a newbie, but not at the
> point where I know how to apply a different surface to the back of an
> object. (Lens is sphere - smaller_sphere)
>
> A pointer would be great at this point.
>
Hi
I think if you give a non-reflective texture to your smaller sphere, it'll
keep it while the csg may have a reflective texture and an interior

Marc

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