> clipka <ano### [at] anonymousorg> wrote:
>> Am 24.07.2012 22:02, schrieb Chaanakya:
>>
>>> My main issue is the transparency of the solid box when the outer box has an IOR
>>> of 1.5 - the solid box should not be even slightly transparent!  Is there
>>> something I'm doing wrong?  Is this a bug?
>>
>> The inner box isn't transparent - it just looks like that because the
>> outer box reflects the pattern of the ground.
>>
>> Rotate the ground plane by y*15 (for instance) to see what I mean.
>
> Okay.  That makes sense.  But shouldn't the image change if I give it an IOR of
> -1.5 (instead of 1.5)?  There's no change in the image.
>
> Thanks for your help!
>
> - Chaanakya
>
>

An ior of -1.5! I've tested with negative ior and it gives me a perfect 
mirror. You are beter to use finish{reflection 1}
This makes sence since the ior is the ratio between the speed of light 
in vacuum and it's speed inside the material.
Inside_Light_Speed = c/ior.
A negative ratio means that the direction of the light is reversed.
With an ior of zero, the result is undefined: Divide by zero.

In your sample, you use reflection{1.0 fresnel} (a prefect mirror! ) 
whitch is equivalent to reflection 1. Note the single reflection value.
As you also have conserve_energy, the 100% reflection means that you 
have 0% transmition. In this case, fresnel have no effect, and the ior 
is useless.

To get a correct result, you should use:
finish{reflection{0, 1 fresnel}conserve_energy}
interior{ior Your_ior}





Alain

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