I am not all that good at writing in native POV so I use MORAY. I also didn't
know what you used for filters so I made so glass with cubes scaled to .05 in 1
axis then gave them red,yellow and dark green glass textures. These are stock in
moray. Anyway I also used a chrome ball instead of mirror. What I got was not at
geometricly exact as yours but was very preasureful to look at. I really kinda
looks like a bunch of galaxies in a far off universe. Really a cool effect.
Thankyou for the suggestion I will keep playing with this. By the way, because
of the glass textures the render time on this one is rather large. It took about
5 minutes to render a 1024 X 768 image with an Atholon 900 running windows ME.
If you are interested I can attach the mdl file so you can render it your self.
Or I can send you a JPG.
Thanks again
Steve Blandford

Dean Wheeler wrote:

> // If you like fractals, chaos theory, stained-glass windows, or
> kaleidoscopes,
> // you will love this one....  Don't worry, it renders pretty fast.
> //
> //
> // fractalballs.pov
> //
> //
> /* POVray scene file by Dean Wheeler, 26 Feb 2000,
> whe### [at] uclink4berkeleyedu
> Background:  This scene replicates a photo on the cover of the Dec. 1999
> issue
> of "The Physics Teacher", published by the American Assoc. of Physics
> Teachers.
> (No, I'm not a physics teacher, but this IS a cool magazine.)  Anyway, this
> scene
> illustrates CHAOTIC SCATTERING of light, i.e. it generates a light FRACTAL.
> Because of the limitations of caustics in POVray, it was necessary to modify
> the
> sources of light and material properties to replicate the effect achievable
> in
> real life.  However, in some ways POVray surpassed what is achievable in
> (geometrically imperfect) real life...
>
> Here is the geometric setup in real life:
>  (1) Four white mirrored spheres are stuck together in a tetrahedral or
>      triangular pyramid formation.  Between any three of the spheres there
> is an
>      opening which goes into the "central cavity."  There are four such
> openings,
>      corresponding to the four faces of a triangular pyramid.  In real life,
> such
>      a set-up can be accomplished using four silver Christmas-tree
> ornaments.
>  (2) Three of the openings are respectively covered with a filter each of a
>      different color.  Lights are set up outside to direct light into the
> central
>      cavity through the three colored filters. A minimal amount of ambient
> light
>      enters the fourth opening.
>  (3) The viewer observes through the fourth opening the fractal pattern
> created
>      in the central cavity.
>
> For POVray, I instead use one bright light coincident with the camera.  This
> light
> has THE EFFECT OF illuminating the three "filters"--which are opaque--from
> the
> inside.  The color that the camera sees at any location in the cavity
> indicates,
> for a ray shot from the camera to that location, which of the four openings
> the
> ray exits (black indicates the fourth opening).  As indicated by the fractal
> nature of the pattern, a finite-sized ray (e.g. a laser beam) shot at any of
> the
> boundaries between colors would exit all four openings simultaineously,
> hence the
> term CHAOTIC SCATTERING.
>
> By playing around with the light-source location(s), material properties,
> etc.,
> some interesting variations can be created.  The default pattern here is a
> good
> starting point...
> */
>
> global_settings { assumed_gamma 2.2 ambient_light 1 max_trace_level 25}
> #declare ri3 = 1/sqrt(3);
> #declare ri6 = 1/sqrt(6);
> #declare v1=<1,-ri3,-ri6>;
> #declare v2=<-1,-ri3,-ri6>;
> #declare v3=<0,2*ri3,-ri6>;
> #declare v4=<0,0,3*ri6>;
> // j alters the surface normals of the colored filters;  try -5<j<5
> #declare j=1;
> // k alters the position and size of filters;  try 0.5<k<2
> #declare k=1;
>
> #camera {location -1.4*v4
>          angle    65
>          look_at  <0,-0.15,0>
>         }
> light_source {-1.4*v4 color rgb 3 shadowless}
> /* location <0,0,0> is the center of the cavity
>    vectors v1..v4 are centers of the spheres
>    use them as basis vectors for placing other objects in the scene */
> #declare tetrahedron = union {sphere {v1, 1 }
>                               sphere {v2, 1 }
>                               sphere {v3, 1 }
>                               sphere {v4, 1 }
>                               finish {ambient 0.03
>                                       diffuse 0
>                                       reflection 0.95}
>                               pigment {color rgb<1,1,1>} }
> #declare filters = union {smooth_triangle {v1,j*v1-v2,v3,j*v3-v2,v4,j*v4-v2
>                                            pigment{color rgb<0,0.5,0.4>}}
>                           smooth_triangle {v1,j*v1-v3,v2,j*v2-v3,v4,j*v4-v3
>                                            pigment{color rgb<0.8,0.8,0.8>}}
>                           smooth_triangle {v2,j*v2-v1,v3,j*v3-v1,v4,j*v4-v1
>                                            pigment{color rgb<0.8,0,0>}} }
> object {tetrahedron}
> object {filters scale k}

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