In article <3c481511@news.povray.org>,
 "Claude Mench" <c.m### [at] adilinstrumentscom> wrote:

>     generaly it is a way to transport light in the interior of
>     objects. I thought that POVRAY medai where only used for
>     athmospheric effects.

Media is just a general "volumetric" effect, it is useful for anything 
that depends on light scattering/absorption/emission in a  3D volume 
instead of a surface. I have done experiments with candles before, using 
media to get a translucent effect.
Here, try this quick-n-dirty scene...it isn't perfect, but demonstrates 
the translucence. Real wax would have some surface characteristics like 
highlights, and I don't know the typical iors of waxes, but that isn't 
too critical since it is nearly opaque.

#include "colors.inc"

#version 3.5;

global_settings {assumed_gamma 1}

#default {finish {ambient 0}}

#declare CamLoc = <0, 3.5,-8>;

camera {
    location CamLoc
    up y*image_height/image_width right x
    angle 35
    look_at <0, 0, 0>
}

light_source {CamLoc color White*0.05}

box {<-100, 0,-100>, < 100, 0, 100>
    texture {pigment {checker color Black, color White}}
}

light_source {< 0, 3.2, 0> color White
    fade_power 2
    fade_distance 2.5
    looks_like {
        sphere {< 0, 0, 0>, 0.2
            texture {
                pigment {color rgb < 1, 0.9, 0.75>}
                finish {ambient 1}
            }
            scale < 1, 2, 1>
        }
    }
}


difference {
    merge {
        cylinder {< 0, 0, 0>, < 0, 1, 0>, 1}
        sphere {< 0, 0, 0>, 1 scale < 1, 2, 1> translate y*1}
    }
    sphere {y*3, 0.5}
    
    // replace with "rgb 1" to see effect without translucence
    texture {pigment {color rgb 1}}
    hollow
    interior {
        ior 1.5
        media {
            scattering {1, color < 1, 0.15, 0.15>*3 extinction 0}
            absorption color rgb < 0.8, 1, 1>*6
            
            method 3 intervals 3 samples 5
        }
    }
}

-- 
 -- 
Christopher James Huff <chr### [at] maccom>

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