Le 19-01-09 à 03:04, hjkqed a écrit :
> Hello.
> 
> I've been trying to simulate a rather simple phenomenon in physics wherein some
> light will be reflected and transmitted when passing through two media of
> different indices of refraction, where the intensities of the
> reflection/transmission depend on the how much the difference is. (pg. 405,
> Introduction to Electrodynamics, Griffiths. Fourth Edition).
> 
> So, technically, if we have a glass box placed in air with an ior != 1 (say, ior
> = 2) then, when we shine light on the box, we should get some reflection of
> light.
> 
> I've been trying to recreate this phenomenon using the source code below, but I
> could not get any sort of reflection. Could anyone please help me why it doesn't
> work? Thank you so much in advance.
> 
> --- code ---
> #include "colors.inc"
> #include "Glass.inc"
> #include "textures.inc"
> 
> global_settings {
>   assumed_gamma 1.0
>   photons
>    { count 2000 }
> }
> 
> camera {location <0,0,-9> look_at <0,0,1> }
> light_source {
>   <0,0,-10>
>   color White
> }
> background { Black }
> 
> box {
>   <-3,-3,0>, <3,3,3>
>   pigment { Col_Glass_Clear } interior {ior 2}
>   finish { reflection { fresnel on }}
>   photons { target reflection on refraction on}
> }
> 
> box {
>   <-3,-3,3>, <3,3,6>
>   pigment { Col_Glass_Clear } interior {ior 1}
>   finish { reflection { fresnel on }}
>   photons { target reflection on refraction on}
> }
> 
> 
> 

As Clipka said, plus, the camera can never directly see the photons.
When using photons, you need some surface for them to show on.
To «see» the light, the finish need to have highlights enabled using 
specular or phong. Using a looks_like or associating some object with 
the light_source using an union is also an option.

finish { reflection { fresnel on }} mean finish{reflection{ 0 fresnel}}
It need to be : finish { reflection{ 1  fresnel}}
The «on» is optional. Default to «off» when fresnel is absent, and to 
«on» when present.

There is no need to use the hollow option. Here, it don't affect 
anything. It's only use is to make an object able to contain some media. 
Nothing else.

In the current sample, you don't need to include glass.inc and 
texture.inc as you use nothing from those.

The box with an IOR of 1 can be removed as it's invisible and have no 
effect at all. The whole environment have an IOR of 1 by default.

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