The following code should produce something looking like a "vulcano
crater"
using a lathe object.

However, the center portion around the symmetry point (center of the
vulcano)
does not render properly.

This looks a bit like the bug concerning a too large value of EPSILON
which is
reported in this newsgroup.

I did, however, find any reference to EPSILON in config.ini. How can I
change it and
does it really solve the problem ?

// lathe rendering does not render properly in the vicinity of <0,0,0>
// Win95 4.00.950B PII 300
// Povray 3.1e.msvc.win32 (PII optimized)
// File by Stefan Hahn ste### [at] t-onlinede

global_settings { assumed_gamma 2.2 }


#declare eye = <-0.3,0.5,-0.3>

   lathe {
      linear_spline 4
      <0.000,0>
      <0.01,0.004>
      <0.02,0.0>
      <0.000,0>
      interior {ior 1.2} pigment {colour rgb<1,1,1>} finish{ambient 0.2
diffuse 0.8}
   }

camera {
   angle 1
   location eye
   up <0, 0.5, 0> right <0.6666, 0, 0>
   look_at <0,0,0>
}



light_source { <10, 100, -100> colour rgb<1,1,1> }

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Stefan Hahn <Ste### [at] t-onlinede> wrote:
: However, the center portion around the symmetry point (center of the
: vulcano) does not render properly.

  Seems like a precision problem. Scaling everything by about 10 solves
the problem.

  This is the core of the problem:

#declare Scale = 1;

#declare eye = <-0.3,0.5,-0.3>*Scale;
lathe
{ linear_spline 2
  <0,0> <.01,.004>*Scale
  pigment { rgb 1 }
}
camera { angle 1 location eye look_at 0 }
light_source { y*10,1 }


  If you set Scale to 10, everything seems to be ok.

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

Post a reply to this message

Dear Nieminen,

Thanks a lot for the fix. Since this problem was only part of a larger
model, in which I dimensioned all using physical parameters [meters]
your fix looked a bit inconvenient.

However, a slight modification of your code seems to be the
perfect fix:
modeling the lathe at a dimension 10 like you proposed, but scaling the whole
object
down it by a factor of 10 immediately afterwards worked out equally well.
Thanks again.

Unfortunately after this fix, I just fell into the next hole concerning
CSG intersections of a transparent lathe's. I am hoping to be helped
out of this hole as well. (see subsequent posting)

***sth***

Nieminen Mika schrieb:

> Stefan Hahn <Ste### [at] t-onlinede> wrote:
> : However, the center portion around the symmetry point (center of the
> : vulcano) does not render properly.
>
>   Seems like a precision problem. Scaling everything by about 10 solves
> the problem.
>
>   This is the core of the problem:
>
> #declare Scale = 1;
>
> #declare eye = <-0.3,0.5,-0.3>*Scale;
> lathe
> { linear_spline 2
>   <0,0> <.01,.004>*Scale
>   pigment { rgb 1 }
> }
> camera { angle 1 location eye look_at 0 }
> light_source { y*10,1 }
>
>   If you set Scale to 10, everything seems to be ok.
>
> --
> main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
> ):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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