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30 Jul 2024 16:22:20 EDT (-0400)
  basic isosurfaces (Message 1 to 4 of 4)  
From: Matthew Pace
Subject: basic isosurfaces
Date: 25 Feb 2004 21:30:17
Message: <matthewpace-13245A.18302325022004@news.povray.org>
Well, it is not showing up, please tell me why.  Sorry to bother you 
Gurus with such ridiculously simple questions...  I only hope its not as 
bad as my media question (forgetting to put "hollow" in there)...

Thanks again!


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From: Hughes, B 
Subject: Re: basic isosurfaces
Date: 25 Feb 2004 22:10:00
Message: <403d6388$1@news.povray.org>
"Matthew Pace" <mat### [at] earthlinknet> wrote in message
news:matthewpace-13245A.18302325022004@news.povray.org...
> Well, it is not showing up, please tell me why.

Heh-heh. Let me guess. You made a isosurface which uses some sort of
function and it isn't visible where it ought to be, right? Two main (and
essentially same) possibilities come to mind. Either 'threshold' or the
equation needs adjusting. First thing to try is using threshold greater than
0 (zero is default). If something shows up by using, say, 1 then I guess you
have an unbalanced equation. That meaning, a surface isn't being found for
threshold 0 but instead might be at another point in space.

Hopefully your camera isn't inside the isosurface. And it could also be a
"max_gradient too low" problem where parts won't appear correctly until its
value is raised. Yet another reason could be from doing a difference or
intersection on the isosurface without using all_intersections keyword in
the iso.

Not sure if I covered all the bases here, or even the right way, but that's
my little assessment of the situation.

Bob H.


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From: Warp
Subject: Re: basic isosurfaces
Date: 26 Feb 2004 05:18:53
Message: <403dc80c@news.povray.org>
Matthew Pace <mat### [at] earthlinknet> wrote:
> Well, it is not showing up, please tell me why.

  How do you expect us to know what you have done if you don't show us?

  Please post a small scene which shows your problem.

-- 
plane{-x+y,-1pigment{bozo color_map{[0rgb x][1rgb x+y]}turbulence 1}}
sphere{0,2pigment{rgbt 1}interior{media{emission 1density{spherical
density_map{[0rgb 0][.5rgb<1,.5>][1rgb 1]}turbulence.9}}}scale
<1,1,3>hollow}text{ttf"timrom""Warp".1,0translate<-1,-.1,2>}//  - Warp -


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From: Matthew Pace
Subject: Re: basic isosurfaces
Date: 28 Feb 2004 12:34:40
Message: <matthewpace-96FE7A.09343928022004@news.povray.org>
In article <403dc80c@news.povray.org>, Warp <war### [at] tagpovrayorg> 
wrote:

> Matthew Pace <mat### [at] earthlinknet> wrote:
> > Well, it is not showing up, please tell me why.
> 
>   How do you expect us to know what you have done if you don't show us?
> 
>   Please post a small scene which shows your problem.

oops, I am sorry, I meant to, but must have forgotten to paste the 
code...  Its working now...  sorta, here is the code if you are curious

I adjusted the max gradient and the threshold






camera
{
   location <2,2,-13>
   look_at  <0 ,0,0>
}
light_source
{
   <2,0,-5>
   color rgb 3
}
#declare myfunct= function(x,y,z,r){x*x+y*y+z*z-r*r};
isosurface
{
// function{myfunct(x,y,z,2)}
   function{(x*x)+(y*y)+(z*z)-(2.5*2.5)}
   threshold 2
   max_gradient 2
   contained_by {sphere {0,3}}
   pigment
   {
      color rgb <.8,.2,.8>
   }
}
plane
{
   y,-4
   pigment
   {
      color rgb .85
   }
   
}


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