"Tim Attwood" <tim### [at] comcastnet> wrote:
> > scaling an object doesn't reduce its density. Eight thousand times a piece
> > of steel is a piece of steel, not a piece of super-sparse steel.
>
> Yeah, the density isn't dependent on scale, I forgot that.
> This should work with diferent radius planets.
>
> #declare PlanetRadius = 50;
>
> #declare PlanetAtmosphere = sphere { <0,0,0>, 1
>    hollow
>    material {
>       texture {
>          pigment { rgbt <1,1,1,1> }
>       }
>       interior {
>          media {
>             emission <0,0,2>
>             density {
>                spherical
>                color_map {
>                   [0 rgb 0]
>                   [0.05 rgb 1/PlanetRadius]
>                   [0.05 rgb 0]
>                   [1 rgb 0]
>                }
>             }
>          }
>          media {
>             emission <2,2,0>
>             density {
>                spherical
>                color_map {
>                   [0 rgb 0]
>                   [0.05 rgb 0.25/PlanetRadius]
>                   [0.05 rgb 0]
>                   [1 rgb 0]
>                }
>             }
>          }
>       }
>    }
>    scale 1.05
> }
>
> #declare PlanetSurface = sphere { <0,0,0>, 1
>    pigment {
>       image_map {
>          jpeg "earth02.jpg"
>          map_type 1
>       }
>       rotate <0,-150,0>
>    }
> };
>
> #declare Planet = union {
>    object {PlanetAtmosphere}
>    object {PlanetSurface}
>    scale PlanetRadius
> };
>
> object {
>    Planet
>    translate <-PlanetRadius,0,0>
> }

Please ignore my last post - I realized the JPEG file was in a different folder.
 Even then, I had to play with the scales between this include file and the
master POV file to get it to look right.  I found out that if I did the scaling
in this include file, then presented it as a scale of "1" in the master POV
file, it looks great. Thank you to those who responded to my pleas for help!

James Lake

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