"Bald Eagle" <cre### [at] netscapenet> wrote:

>
> F(x,y,z,t) =
> select ( (y<(44/10)) * (y>-(24/10)),
> 0, 1, ThickIsoExterior((10*x/15),y,z,t)
> )
>
> Hope that makes sense.

Hi BE,
I followed your advice with respect to select() and added the appropriate code
using the boolean & instead of multiply.

And it works - well, not the way it should.
I believe there is something wrong in my Povray code which is hard for me to
find out.

I added AT's equations as comment above the Povray code.

Meanwhile I read the threads initiated by klp in Povray's advanced users
<6752dcbc@news.povray.org>
in Dec 2024 about the topic but I could not find the solution there.

The interesting thing about my misinterpretation of AT's equations is:

 (1) setting threshold 1 and accuracy 0.01 (max_gradient 2352446)
 ==> Povray renders something solid (not the object I was expecting)
 ==> Trace Time: 1h 38 min using 16 threads
 (2) setting threshold 0 and accuracy 0.01 (max_gradient 2352446)
 ==> Povray renders something invisible
 ==> Trace Time: about the same as above
 (3) setting threshold 0.01 and accuracy 0.1 (max_gradient 2352446)
 ==> Povray renders an object that looks like being peeled
 ==> Trace Time: 0h 39 min using 16 threads
 And no, Povray doesn't complain about gaps in the object!

I will post an image of (1) and (3) in p.b.i

Thanks for your patience

Droj

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