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From: Lukas Winter
Subject: ocean wave simulation
Date: 2 May 2007 11:52:27
Message: <pan.2007.05.02.15.52.25.967812@removeit.geloescht.net>
At the moment I am integrating "aqua library"
(http://savannah.nongnu.org/projects/aqua/), a library that simulates
ocean surfaces, into povray as a patch. The patch reads in vertex and
normal data from the library and converts them to an (almost) rectangular
smooth mesh. What I think is the best about it, is, that the surface is
theoretically fully animatable, tileable and even loopable. Unfortunately
at the current state of the patch the surface cannot be animated, because
libaqua seeds its random generator internally with the current time. The
corresponding SDL-code looks like this:
water_mesh
{
  precompute 512, 512, 4 
  /*number of points in x and z direction, displacement in normal
  direction ("sharpness" of the waves)*/
  size <100, 100>  //size in metres and pov-units respectively
  waves .1, 200  //smallest and largest wavelength (term from the library)
  phase clock  //animation parameter, in seconds?
  water_level 10  //depth (term from the library) of the water
  repeat 1  //number of seconds? before the animation repeats
  method 1
  /*1, 2 and 3 stand for different generation methods, but only 1 is
  implemented at the moment (fft::Surface_Pierson_Ug)*/
  form 1.0  //spectrum factor (term from the library)
}

I have no clue what water_level/depth and form/spectrum factor actually
do, but not all methods use the same parameters. A way to change the wind
speed and its direction is currently not supported. An image says more
than thousand words, as a german saying goes:
http://geloescht.net/allerlei/test_waves.jpg
You can see where two tiles overlap a bit on the left. There is no foam,
the bright spots on the right are highlights. I don't know if I can or
will release the source code, as aqaulib's license is GPL and there are
still some unimplemented parts in it.
Lukas


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From: scam
Subject: Re: ocean wave simulation
Date: 2 May 2007 20:00:01
Message: <web.4639250593cea65a5897f1740@news.povray.org>
Lukas Winter <web### [at] removeitgeloeschtnet> wrote:
> At the moment I am integrating "aqua library"
> (http://savannah.nongnu.org/projects/aqua/), a library that simulates
> ocean surfaces, into povray as a patch.

I can't offer any help, but I think this could be very useful and I hope you
are able to see it through. The water looks very nice to me, and if it could
be realistically animated that would be awesome. Good luck.


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From: Marc
Subject: Re: ocean wave simulation
Date: 3 May 2007 05:47:22
Message: <4639afaa$1@news.povray.org>

news: pan### [at] removeitgeloeschtnet...
> At the moment I am integrating "aqua library"

That looks very promising!

Marc


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From: Thomas de Groot
Subject: Re: ocean wave simulation
Date: 3 May 2007 08:25:42
Message: <4639d4c6$1@news.povray.org>
Sincerely, that looks excellent. I wish it could be come the "Ivy Generator" 
of oceans!!!
Good luck!

Thomas


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From: Lukas Winter
Subject: Re: ocean wave simulation
Date: 4 May 2007 10:57:45
Message: <pan.2007.05.04.14.57.44.896828@removeit.geloescht.net>
I got a response from the author of libaqua. He asked me to verify whether
a GPLed library could indeed not be linked to POV-Ray without changing the
license. Is there anyone here, who knows enough about the license of
POV-Ray 3.6 to tell me, whether I am allowed to release  the source code
of my patch, if I am using a library released under GPL which in turn uses
FFTW and GSL (both also released under GPL)?


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From: William Tracy
Subject: Re: ocean wave simulation
Date: 4 May 2007 11:24:42
Message: <463b503a$1@news.povray.org>
Lukas Winter wrote:
> I got a response from the author of libaqua. He asked me to verify whether
> a GPLed library could indeed not be linked to POV-Ray without changing the
> license. Is there anyone here, who knows enough about the license of
> POV-Ray 3.6 to tell me, whether I am allowed to release  the source code
> of my patch, if I am using a library released under GPL which in turn uses
> FFTW and GSL (both also released under GPL)?

You probably can't share the finished work--GPL code cannot be used 
inside non-GPL programs. There's nothing wrong with releasing the 
*patch* itself, and letting people compile it themselves, though.

Otherwise, the GPL code can call other code, but the other code cannot 
call the GPL code, if that's possible.

Barring that, you need to get someone to change to a different license. :-(

-- 
William Tracy
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|a|f|i|s|h|i|o|n|a|d|o|@|g|m|a|i|l|.|c|o|m|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|w|t|r|a|c|y|@|c|a|l|p|o|l|y|.|e|d|u|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

You know you've been raytracing too long when a co-worker nearly kills 
himself over losing an hour's worth of work after a computer crash, and 
you just calmly shrug your shoulders and say, "Is that all?"
Taps a.k.a. Tapio Vocadlo


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From: Tim Attwood
Subject: Re: ocean wave simulation
Date: 4 May 2007 18:10:38
Message: <463baf5e$1@news.povray.org>
"> You probably can't share the finished work--GPL code cannot be used
> inside non-GPL programs. There's nothing wrong with releasing the *patch* 
> itself, and letting people compile it themselves, though.
>
> Otherwise, the GPL code can call other code, but the other code cannot 
> call the GPL code, if that's possible.
>
> Barring that, you need to get someone to change to a different license. 
> :-(

IMHO POV's license is GPL-compatible.


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From: William Tracy
Subject: Re: ocean wave simulation
Date: 5 May 2007 01:40:25
Message: <463c18c9@news.povray.org>
Tim Attwood wrote:
> IMHO POV's license is GPL-compatible.

In what sense? If I recall right (which is a big if) it makes extra 
restrictions (no commercial derivatives, for one) that the GPL forbids.

-- 
William Tracy
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|a|f|i|s|h|i|o|n|a|d|o|@|g|m|a|i|l|.|c|o|m|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|w|t|r|a|c|y|@|c|a|l|p|o|l|y|.|e|d|u|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

You know you've been raytracing too long when you spend $2000 on 
upgrading your computer so that POV-Ray runs faster, and you scoff at 
Rhino for costing so much.


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From: Lukas Winter
Subject: Re: ocean wave simulation
Date: 5 May 2007 05:23:11
Message: <pan.2007.05.05.09.23.10.376056@removeit.geloescht.net>
Am Fri, 04 May 2007 08:24:42 -0700 schrieb William Tracy:
> 
> You probably can't share the finished work--GPL code cannot be used inside
> non-GPL programs. There's nothing wrong with releasing the *patch* itself,
> and letting people compile it themselves, though.
> 
> Otherwise, the GPL code can call other code, but the other code cannot
> call the GPL code, if that's possible.
> 
> Barring that, you need to get someone to change to a different license.
> :-(

Does that mean I can release diffs of the POV source files, as long as I
don't offer any GPLed library (so someone who wants to compile this patch
has to download the libraries himself)? Can I release the fully patched
POV source files? I don't care, which license the patch will be released
under, because writing it is just a simple task of having a closer look at
Aqua Library and POV-Ray and then combining the two.
Otherwise I'll simply write an application, which exports the data as a
mesh2. Many people don't want to compile things themselves anyway.


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From: Marc
Subject: Re: ocean wave simulation
Date: 5 May 2007 06:27:45
Message: <463c5c21$1@news.povray.org>

news: pan### [at] removeitgeloeschtnet...
.
> Otherwise I'll simply write an application, which exports the data as a
> mesh2. Many people don't want to compile things themselves anyway.

That's so true :-D
Good Idea!

Marc


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