How: use CSG to give the front and back faces different textures, the 
front in this case is 90% reflective, with 10% transmission, and the 
back face is simply 50% filtering. When seen from the front, objects 
behind the glass are filtered through both layers while reflections are 
unfiltered. When seen from the back, objects behind the glass pass 
through the same layers, but the reflections are filtered twice. Here's 
the code for the objects:

difference {
    sphere {< 0, 1, 0>, 1
        texture {
            pigment {color rgb 1 transmit 0.1}
            finish {ambient 0 diffuse 0 reflection 0.9}
        }
    }
    sphere {< 0, 1, 0>, 1 scale < 1, 1, 0.8>
        texture {
            pigment {color rgb 1 filter 0.5}
            finish {ambient 0 diffuse 0}
        }
    }
    plane {-z, 0 pigment {color rgb 0}}
    scale < 1, 1, 0.2>
}

-- 
Christopher James Huff <cja### [at] gmailcom>
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/

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Attachments:
Download 'onewayglass.png' (109 KB)

Preview of image 'onewayglass.png'

Nobody ever pays attention to my posts.  :P

A while back I demonstrated that POV can do one-way mirrors the same way 
they're done in the real world; make a material 50% transparent and 50% 
reflective, with one side being lit far more than the other.  That's all 
it takes.

-- 
Tim Cook
http://home.bellsouth.net/p/PWP-empyrean

-----BEGIN GEEK CODE BLOCK-----
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GFA dpu- s: a?-- C++(++++) U P? L E--- W++(+++)>$
N++ o? K- w(+) O? M-(--) V? PS+(+++) PE(--) Y(--)
PGP-(--) t* 5++>+++++ X+ R* tv+ b++(+++) DI
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In article <4225f84a@news.povray.org>, Tim Cook <z99### [at] bellsouthnet> 
wrote:

> A while back I demonstrated that POV can do one-way mirrors the same way 
> they're done in the real world; make a material 50% transparent and 50% 
> reflective, with one side being lit far more than the other.  That's all 
> it takes.

That's not the way they are in the real world...that's just a 
half-silvered mirror. This is a half-silvered mirror with a filtering 
layer on the less reflective side. Both sides are equally bright in this 
case...having the viewing side be darker makes the effect stronger, but 
is not necessary. This is a fairly accurate way to model real-world 
one-way mirrors.

-- 
Christopher James Huff <cja### [at] gmailcom>
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/

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Tim Cook wrote:

> Nobody ever pays attention to my posts.  :P

If it makes you feel any better, I remember your post. :)

-Xplo

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news:42260bae$1@news.povray.org...
> Tim Cook wrote:
>
> > Nobody ever pays attention to my posts.  :P
>
> If it makes you feel any better, I remember your post. :)
But if it makes you feel even better, I don't rember your post at all :p

Marc

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Christopher James Huff wrote:

> That's not the way they are in the real world...that's just a 
> half-silvered mirror. This is a half-silvered mirror with a filtering 
> layer on the less reflective side. Both sides are equally bright in this 
> case...having the viewing side be darker makes the effect stronger, but 
> is not necessary. This is a fairly accurate way to model real-world 
> one-way mirrors.

That seems to be the way those obnoxious reflective sunglasses are made, 
but IIRC, two-way mirrors are a bit different.

And couldn't the 50/50 effect be acheived with conserve_energy?


-- 
~Mike

Things! Billions of them!

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In article <42261692$1@news.povray.org>,
 Mike Raiford <mra### [at] hotmailcom> wrote:

> That seems to be the way those obnoxious reflective sunglasses are made, 
> but IIRC, two-way mirrors are a bit different.
> 
> And couldn't the 50/50 effect be acheived with conserve_energy?

The conserve_energy option is mainly useful with variable reflection. I 
only used constant reflection, and with the settings I used energy is 
conserved, though a more realistic scene would use reflection and 
transmission that total to less than 100% since in practice we can't 
make a surface that doesn't absorb any light.

We once had a one-way mirror on a porch door. It was really one way, if 
you held it open so both sides faced the same environment, you could see 
through it one way but not the other. When the mirrored layer scratched 
off, you could see that there was a dark layer under it, so from one 
side reflections were filtered twice while from the other they were 
unfiltered. If you put it between two equally lit rooms, only one would 
easily see the other. A dark room would see a light room through it both 
ways, but one of the ways would work much better.

-- 
Christopher James Huff <cja### [at] gmailcom>
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/

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