POV-Ray : Newsgroups : povray.binaries.utilities : Wood program but still develop : Re: Wood program but still develop Server Time
2 Oct 2022 18:36:09 EDT (-0400)
  Re: Wood program but still develop  
From: Bald Eagle
Date: 23 Aug 2022 06:55:00
Message: <web.6304b1885b6ed241f9dae3025979125@news.povray.org>
"And" <49341109@ntnu.edu.tw> wrote:
> "Bald Eagle" <cre### [at] netscapenet> wrote:
> > "And" <49341109@ntnu.edu.tw> wrote:
> >
> > I didn't read this paper (yet), but it just showed up in my email inbox.
> > Maybe it will inspire some ideas, serve as an entry to other similar research
> > papers, and be of some practical use in developing your challenging project.
> >
> > (I hadn't thought of using L-systems!)
> >
> > -BW
> >
> >
> Oh, ... I wouldn't like to make any detailed tree trunk "3D Model"(that is
> another
> challenge), I just generate a (3D)texture. I implement my texture in POV-Ray,
> outputting "pigment {...}" as its final form.

Naturally.  The wood pigment patterns we've almost all been using for the past
30 years are just a bunch of concentric cylindrical rings.   Seems to work well
enough for most purposes.
To add a bit of realism by simulating the cross-section of those 3D branches,
the black hole warp can be used, and that's what I was thinking when I suggested
looking this over - not copying the paper's method verbatim.

So rather than create a whole 3D tree and then slice it (which would necessarily
limit the pattern to the locus of the individually modeled tree), I was thinking
that you could assemble a pattern of black hole warps using an L-system in code,
which would then be used to define the pigment {}.

I my mind, this would be very much like the way Tor Olav Kristensen uses a macro
to assemble the terms of a long Bernstein polynomial function.

jr has also done a lot of development using the method of including the parsed
text of temporary files to assemble complex data/code structures, as well as
some pretty complex data "trees" - which might serve as inspiration to you or
others for generating complex pigment pattern definitions.

TdG may have code of a similar nature in his vast archive, or have other ideas
of his own about how to approach the branch/knot aspect of the wood pattern.

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