Hi,

Last weekend I've encountered a strange behavior in the official Pov 3.1
for Windows which I would take for an error.

If you define a layered media and transform it later on, only the first
media after the define is transformed. The other media are not affected
by the transform, but are rendered beside this correctly.

The following code shows exemplary the error for 'translate', but it als
occurs for 'scale'. For all other transforms I didn' t test it, but I
think it will occur for most of them.

However you could work around this error by declaring the multilayer
media as single medias and combine them transformed as needed in the
object, but for very complex medias this would cancel the advantage of
defines to handle them as one unit, especially if you use the same media
multiple times but differently transformed.

Your Axel Baune

PS: By the way: Pov-Ray is a great work.

----- Example code --------

// declare multilayered media

#declare med = media {
  emission <1,0,0>
  density {
     spherical
  }
}
media {
  emission <0,0,1>
  density {
     spherical
  }
}

// use declared media

sphere { 0, 1
  texture { pigment rgbt 1 }
  interior {
     media {
        med
        translate <1,0,0>
     }
  }
}

----- Used Resourcen -----

Pov:Pov-Ray 3.1 for Windows (official)

CPU: AMD K6-2 300 3D Now

OS: Windows 95B with USB Support

--
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Axel Baune                                            Phone:  +49 731 502 4242
Department of Neural Information Processing             Fax:  +49 731 502 4156
University of Ulm
89069 Ulm                            email: aba### [at] neuroinformatikuni-ulmde
Germany                            URL (privat): http://www.uni-ulm.de/~abaune
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In article <3646C773.B258A1BD@neuro.informatik.uni-ulm.de> , Axel Baune
<aba### [at] neuroinformatikuni-ulmde>  wrote:
>#declare med = media {
>  emission <1,0,0>
>  density {
>     spherical
>  }
>}
>media {
>  emission <0,0,1>
>  density {
>     spherical
>  }
>}
>
>// use declared medi

Do you assume that both media are stored in med? This will not happen because
#declare takes only one value (see the doc "Declaring identifiers"). What happens
seems to be that you create a scene level media, see the docs "Atmospheric Media"
section.


    Thorsten


Using it this way should work:

#declare med = interior {
  media { 
    emission <1,0,0> 
    density { 
       spherical 
    } 
  } 
  media { 
    emission <0,0,1> 
    density { 
       spherical 
    } 
  }
}

sphere { 0, 1 
  texture { pigment rgbt 1 } 
  interior { 
     med
    translate <1,0,0> 
  } 
}

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: Tho### [at] csicom

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Hi,

I know it's a little bit late, but:

_Sorry_, it was my fault to call the problem an error. Should have read the
documentation better. By the way: (I think this is a feature request, but ...) In my
opinion the old documentation of Pov 3.0 was much more understandable as the new
one. However for medias this doesn't help much ;-)

Thanks again for your help/correction of my fault

Yours, Axel Baune

--
------------------------------------------------------------------------------
Axel Baune                                            Phone:  +49 731 502 4242
Department of Neural Information Processing             Fax:  +49 731 502 4156
University of Ulm
89069 Ulm                            email: aba### [at] neuroinformatikuni-ulmde
Germany                            URL (privat): http://www.uni-ulm.de/~abaune
------------------------------------------------------------------------------

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