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  Media in a torus (Message 1 to 5 of 5)  
From: gemelli david
Subject: Media in a torus
Date: 4 Dec 1998 03:25:24
Message: <36679D03.F2CACD3A@imerir.asso.fr>
Hi,
I am currently doing a scene where an atomic bomb is exploding on a
futuristic battlefield.
I have made a dust wave using a torus and media but the result isn't
very good.
What media feature can I use to make realistic dust (it must be a
colored dust).
Is it possible to make a gradient from the center of the torus donut (is
that the expression ?)
to its surface ?
    Thanks.
                                                David.
This is the what I am currently using:

#local Dust_Media_1 =
media {
     absorption 0.3
     intervals 20
     density {
          gradient y
          turbulence 0.2
          color_map {
               [0 color rgb<0.7,0.7,0.9>]
               [0.6 color rgb<0.5,0.6,0.8>]
               [0.98 color rgb<0,0,0>]
               [1 color rgb<0,0,0>]
          }
     }
}

#local Dust_Media_2 =
media {
     emission 0.08
     intervals 20
     density {
          gradient y
          turbulence 0.2
          color_map {
               [0 color rgb<0.456863,0.319608,0.037255>]
               [0.9 color rgb<0.556863,0.419608,0.137255>]
               [0.95 color rgb<0,0,0>]
               [1 color rgb<0,0,0>]
          }
     }
}

torus {
     (40 * CLOCK_DUST) + 1
     1.8
     pigment {rgbt <1,1,1,1>}
     interior {
          media {
               Dust_Media_1
               scale <2,2,2>
          }
          media {
               Dust_Media_2
               scale <2,2,2>
          }
     }
     scale <2, 2, 2>
     translate <0,(20*(1/256)*100)-(4*ALTITUDE_DUST),0>
     hollow
}


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From: =Bob
Subject: Re: Media in a torus
Date: 6 Dec 1998 19:56:05
Message: <366b27a5.0@news.povray.org>
I thought maybe someone would have responded to your asking for help by now.
I can say, try a 'spherical' density instead of a gradient one but I don't 
know what the end product is supposed to look like. All I could tell is the 
torus grows wider along the ground plane.
I expected it to be more like a fireball in the air.
Anyway, spherical is one possibility, perhaps scaled smaller in the y than in 
the x an z (scale <1,0.5,1>). And speaking of scale, when media is scaled up 
it intensifies the effect of the media used, scaled down it de-intensifies. 
So, try and setup the media into the object first and then adjust the density 
color values up or down.
Another way is to use 'scattering' as well and adjust it (it can use a color 
vector too).
There's my hints.

Message <36679D03.F2CACD3A@imerir.asso.fr>, gemelli david  typed...
>
>Hi,
>I am currently doing a scene where an atomic bomb is exploding on a
>futuristic battlefield.
>I have made a dust wave using a torus and media but the result isn't
>very good.
>What media feature can I use to make realistic dust (it must be a
>colored dust).
>Is it possible to make a gradient from the center of the torus donut (is
>that the expression ?)
>to its surface ?
>    Thanks.
>                                                David.
>This is the what I am currently using:
>
>#local Dust_Media_1 =
>media {
>     absorption 0.3
>     intervals 20
>     density {
>          gradient y
>          turbulence 0.2
>          color_map {
>               [0 color rgb<0.7,0.7,0.9>]
>               [0.6 color rgb<0.5,0.6,0.8>]
>               [0.98 color rgb<0,0,0>]
>               [1 color rgb<0,0,0>]
>          }
>     }
>}
>
>#local Dust_Media_2 =
>media {
>     emission 0.08
>     intervals 20
>     density {
>          gradient y
>          turbulence 0.2
>          color_map {
>               [0 color rgb<0.456863,0.319608,0.037255>]
>               [0.9 color rgb<0.556863,0.419608,0.137255>]
>               [0.95 color rgb<0,0,0>]
>               [1 color rgb<0,0,0>]
>          }
>     }
>}
>
>torus {
>     (40 * CLOCK_DUST) + 1
>     1.8
>     pigment {rgbt <1,1,1,1>}
>     interior {
>          media {
>               Dust_Media_1
>               scale <2,2,2>
>          }
>          media {
>               Dust_Media_2
>               scale <2,2,2>
>          }
>     }
>     scale <2, 2, 2>
>     translate <0,(20*(1/256)*100)-(4*ALTITUDE_DUST),0>
>     hollow
>}
>

-- 
 omniVERSE: beyond the universe
  http://members.aol.com/inversez/POVring.html
=Bob


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From: gemelli david
Subject: Re: Media in a torus
Date: 8 Dec 1998 06:39:59
Message: <366D0FE2.DD559655@imerir.asso.fr>
Thanks for your suggestions, but the spherical item doesn't seem to make the dust
more
realistic. I've posted a very little and poor quality image (in binaries.image
title:"My dust is very bad") to show what I have by now.
Maybe someone can help me regarding to this example.
                        David



> I thought maybe someone would have responded to your asking for help by now.
> I can say, try a 'spherical' density instead of a gradient one but I don't
> know what the end product is supposed to look like. All I could tell is the
> torus grows wider along the ground plane.
> I expected it to be more like a fireball in the air.
> Anyway, spherical is one possibility, perhaps scaled smaller in the y than in
> the x an z (scale <1,0.5,1>). And speaking of scale, when media is scaled up
> it intensifies the effect of the media used, scaled down it de-intensifies.
> So, try and setup the media into the object first and then adjust the density
> color values up or down.
> Another way is to use 'scattering' as well and adjust it (it can use a color
> vector too).
> There's my hints.
>
> Message <36679D03.F2CACD3A@imerir.asso.fr>, gemelli david  typed...
> >
> >Hi,
> >I am currently doing a scene where an atomic bomb is exploding on a
> >futuristic battlefield.
> >I have made a dust wave using a torus and media but the result isn't
> >very good.
> >What media feature can I use to make realistic dust (it must be a
> >colored dust).
> >Is it possible to make a gradient from the center of the torus donut (is
> >that the expression ?)
> >to its surface ?
> >    Thanks.
> >                                                David.
> >This is the what I am currently using:
> >
> >#local Dust_Media_1 =
> >media {
> >     absorption 0.3
> >     intervals 20
> >     density {
> >          gradient y
> >          turbulence 0.2
> >          color_map {
> >               [0 color rgb<0.7,0.7,0.9>]
> >               [0.6 color rgb<0.5,0.6,0.8>]
> >               [0.98 color rgb<0,0,0>]
> >               [1 color rgb<0,0,0>]
> >          }
> >     }
> >}
> >
> >#local Dust_Media_2 =
> >media {
> >     emission 0.08
> >     intervals 20
> >     density {
> >          gradient y
> >          turbulence 0.2
> >          color_map {
> >               [0 color rgb<0.456863,0.319608,0.037255>]
> >               [0.9 color rgb<0.556863,0.419608,0.137255>]
> >               [0.95 color rgb<0,0,0>]
> >               [1 color rgb<0,0,0>]
> >          }
> >     }
> >}
> >
> >torus {
> >     (40 * CLOCK_DUST) + 1
> >     1.8
> >     pigment {rgbt <1,1,1,1>}
> >     interior {
> >          media {
> >               Dust_Media_1
> >               scale <2,2,2>
> >          }
> >          media {
> >               Dust_Media_2
> >               scale <2,2,2>
> >          }
> >     }
> >     scale <2, 2, 2>
> >     translate <0,(20*(1/256)*100)-(4*ALTITUDE_DUST),0>
> >     hollow
> >}
> >
>
> --
>  omniVERSE: beyond the universe
>   http://members.aol.com/inversez/POVring.html
> =Bob


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From: Margus Ramst
Subject: Re: Media in a torus
Date: 9 Dec 1998 02:24:19
Message: <366E25B3.6B018CAD@peak.edu.ee>
You can probably get the effect that you want by creating a circular array of
spheres and filling each sphere with a spherical density media. With enough
spheres, the result should look like a donut-shaped media.
Using multiple media containers is rather slow, of course, but you can get
virtually any shape of media you want.

Margus

gemelli david wrote:
> 
> Hi,
> I am currently doing a scene where an atomic bomb is exploding on a
> futuristic battlefield.
> I have made a dust wave using a torus and media but the result isn't
> very good.
> What media feature can I use to make realistic dust (it must be a
> colored dust).
> Is it possible to make a gradient from the center of the torus donut (is
> that the expression ?)
> to its surface ?
>     Thanks.
>                                                 David.


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From: Ilmari Karonen
Subject: Re: Media in a torus
Date: 7 Feb 1999 16:37:53
Message: <36be07b1.0@news.povray.org>
Margus Ramst wrote in message <366E25B3.6B018CAD@peak.edu.ee>...
>You can probably get the effect that you want by creating a circular array
of>spheres and filling each sphere with a spherical density media. With
enough>spheres, the result should look like a donut-shaped media.>Using
multiple media containers is rather slow, of course, but you can
get>virtually any shape of media you want.

Well, I just saw this old post and had to mention that the function
patterns in the Superpatch are great for this:

#macro Toroidal ( Major ) // minor radius always 1
  function { max(0,1-sqrt(x*x+y*y+z*z-Major*(2*sqrt(x*x+z*z)-Major))) }
#end


torus { 5, 1
  hollow
  pigment { rgbt 1 }
  interior {
    media {
      emission <0.5,1.0,1.5>
      density { Toroidal(5) cubic_wave }
    }
  }
}

--
Ilmari Karonen (ilt### [at] scifi)
http://www.sci.fi/~iltzu/


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