Hi all around,

I just read a paper about growing plants to light and came up with a very silly
idea. The paper is "A Simple but Effective Algorithm to Model the Competition of
Virtual Plants for Light and Space" by William Van Haevre and Philippe Bekaert
(2003). One can find it with google easily. They use an open L-System to model
the plant by calculating special photons to determine the direction the plant
will grow. My idea is to simulate a L-System with the animation feature of POV
(writing the actual string to file, read it in the next iteration, perform the
L-System rules and write it out again). To determine the direction of growth I
will not use this complicated photon issue but simply look through the "eyes" of
the seedlings (branches) using the mesh-cam, distribution type 3, evaluating the
brightesst spot with eval_pigment and use this as the new direction. O.k. this
is a very brief scetch of my idea. My question here is: Has someone of you
implemented a L-System with POV so far. If I have to invent the wheel I will do,
but if someone else did it some time ago, I would like to learn about it. My
searches here yielded no hits unfortunatelly.

Best regards,
Michael

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BTW The mesh-cam is a very useful and mighty approvement to POV. Why are Jaime
and I the only users here to play around with it?

Best regards,
Michael

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MichaelJF wrote:

> BTW The mesh-cam is a very useful and mighty approvement to POV. Why are Jaime
> and I the only users here to play around with it?

It's mighty but also not trivial to use (or even understand, I'm not
sure I fully understood what all the modes do myself). Also I gathered
it is mostly useful in elaborate multipass processes. Given that most
hobbyists are less dedicated I think the number of potential users
is smaller than you expect.

Not to mention you also need some kind of mesh. If you don't use
modellers and treat povray as a programming language that turns code
into images, then the mesh cam is a remote feature.

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>MichaelJF  on date 02/01/2013 18.03 wrote:
> My question here is: Has someone of you
> implemented a L-System with POV so far

Years ago, for a irtc entry, I realized a very basic L-System parser.
The code is not well documented, but you can found it in p.b.s.
Paolo

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Paolo Gibellini <p.g### [at] gmailcom> wrote:
> >MichaelJF  on date 02/01/2013 18.03 wrote:
> > My question here is: Has someone of you
> > implemented a L-System with POV so far
>
> Years ago, for a irtc entry, I realized a very basic L-System parser.
> The code is not well documented, but you can found it in p.b.s.
> Paolo

Thanks a lot, but unfortunatelly I can only find a broken link at an Australian
server. Can you remember the picture or the topic? Basic could be suffient for
me, since I intent only a proof of concept at the moment.

Best regards,
Michael

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Christian Froeschlin <chr### [at] chrfrde> wrote:
> It's mighty but also not trivial to use (or even understand, I'm not
> sure I fully understood what all the modes do myself).
Yes, that is true. I think I understand the distribution type 3, which is a
little bit like looking through the object like an eye. But you need not only a
mesh, it must be uv-mapped too. And this uv-mapping can not have overlapping
areas. A ghost I hunted down a while. For texturing purposes overlapping areas
are no problem.

> Also I gathered
> it is mostly useful in elaborate multipass processes. Given that most
> hobbyists are less dedicated I think the number of potential users
> is smaller than you expect.

And yes again, with my experiments with using dynamic hair from poser I had some
1000 objects which needed an individual occlusion map baking. All had to be
sticked together to yield the final image.
>
> Not to mention you also need some kind of mesh. If you don't use
> modellers and treat povray as a programming language that turns code
> into images, then the mesh cam is a remote feature.

In some cases I use POV to create uv-mapped meshes first and then apply the
meshcam e.g. for occlusion map baking. An idea I used for long years with my
statistical software and recogniced that it is possible with POV too by looking
at Gilles makegrass macros some years ago. Yes, you need some experience with
interpreting languages (must not be POV) and their possibilties to come up with
such ideas.

Best regards,
Michael

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> Thanks a lot, but unfortunatelly I can only find a broken link at an Australian
> server. Can you remember the picture or the topic? Basic could be suffient for
> me, since I intent only a proof of concept at the moment.
>
> Best regards,
> Michael
>
>
I've posted the code in p.b.s. (i.e. povray.binaries.scene-files):
http://news.povray.org/povray.binaries.scene-files/thread/%3C50e54231%40news.povray.org%3E/
;-)
Paolo

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"MichaelJF" <mi-### [at] t-onlinede> wrote:
> BTW The mesh-cam is a very useful and mighty approvement to POV. Why are Jaime
> and I the only users here to play around with it?

Probably because I can't make heads or tails of what it even means.

Post a reply to this message

> "MichaelJF" <mi-### [at] t-onlinede> wrote:
>> BTW The mesh-cam is a very useful and mighty approvement to POV. Why are Jaime
>> and I the only users here to play around with it?
>
> Probably because I can't make heads or tails of what it even means.
>

  It means that you can use a mesh surface as a viewing port, or 
something like that... to make a gross analogy, think on a point light 
and a emitting surface: now replace the light rays for camera rays and 
you got it. :)

--
Jaime

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Jaime Vives Piqueres <jai### [at] ignoranciaorg> wrote:

> > "MichaelJF" <mi-### [at] t-onlinede> wrote:
> >> BTW The mesh-cam is a very useful and mighty approvement to POV. Why are Jaime
> >> and I the only users here to play around with it?
> >
> > Probably because I can't make heads or tails of what it even means.
> >
>
>   It means that you can use a mesh surface as a viewing port, or
> something like that... to make a gross analogy, think on a point light
> and a emitting surface: now replace the light rays for camera rays and
> you got it. :)
>
> --
> Jaime

Yes, I interpret the mesh cam (distribution type 3) in a way like looking
through the "eyes of an object". What can be seen from the surface of an object
(the mesh the mesh camera represents)? Is there light or is there darkness? My
idea here was then, what can a sprout see, where is the most light and then grow
in this direction. So far I have only a meta program for the "animation" feature
of pov to yield results here. And I'm confident that it will work. But first I
will go for the next entry at Tina-Chep, I hope you can forgive me. As soon as I
have results to this isuue here, I will post them.

Best regards,
Michael

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