POV-Ray : Newsgroups : povray.newusers : Artefact in lathe object using hollow and interior media emission : Re: Artefact in lathe object using hollow and interior media emission Server Time
3 Dec 2021 12:30:17 EST (-0500)
  Re: Artefact in lathe object using hollow and interior media emission  
From: Alain Martel
Date: 19 Jan 2021 11:21:58
Message: <60070726@news.povray.org>
Le 2021-01-19 à 10:50, nj a écrit :
> I am having trouble with an artifact on a lathe object that uses hollow and
> interior media emission. I simplified my code as much as I could. Specifically,
> the original lathe uses a more complex spline.
> 
> 
> Example code:
> -------------
> 
> #version 3.7;
> 
> camera {
>      location <0,0,-10>
>      look_at 0
> }
> 
> lathe {
>      linear_spline
>      2,
>      <1,-100>, <1,100>
> 
>      hollow on
>      pigment {rgbf 1}
>      interior { media { emission <1,1,1> } }
> }
> 
> 

When using media containers, you need closed objects. Your object is 
open at both ends, meaning that the media is not constrained by that object.

Change your lathe as follow :
lathe {
     linear_spline
     4, // instead of 2
     <0, -100>, // added bottom end cap
     <1,-100>, <1,100>,
     <0, 100> // added top end cap

     hollow //on Default to on when hollow is present
     pigment {rgbf 1}
     interior { media { emission <1,1,1> } }
}

In your original lathe, make sure that the first and last points have a 
zero U coordinate. If not, increase the point count and add the missing 
point.


Alain


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