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GPL or not GPL ?

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GPL or not GPL ?

Postby helijah » Mon Jun 18, 2012 8:31 am

Hi all,

I do not want to create a controversy here but simply put your finger on a strangeness that does not seem to bother many people when it should be. GPL is access to the sources, etc. using free ... Finally, you know. It is also required for any project using all or part of GPL code to be GPL also.

And here is the contradiction. Outerra is under a proprietary license. No access to sources, free demo, but paying for full software etc. ... and Outerra uses ...... JSBSim!

What to conclude? JSBSim is not GPL or Outerra blithely violates GPL with the blessing of the authors of JSBSim.
Nevertheless two things are possible and imperative.

1 - Either JSBSim withdrew from the Outerra project to comply with the GPL
2 - Let JSBSim withdrew from the FG project to enforce the GPL

Now you can resume it in all directions. This is far more serious and important that some non-free files that I could sometimes forget in my creations and that made a fuss a few fanatics.

And if it's pretty fantastic rendering of Outerra you like, to point to ignore the GPL tell you though there are other equally powerful project (see best in my opinion) but totally GPL.
I think of the project "Proland" which in addition to allowing free access to sources provides good documentation and APIs ready:

http://proland.inrialpes.fr/
http://www-evasion.imag.fr/Membres/Eric.Bruneton/

Regards Emmanuel
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Re: GPL or not GPL ?

Postby Thorsten » Mon Jun 18, 2012 9:10 am

Reading up on GPL might have been a good idea...

http://www.gnu.org/licenses/gpl-faq.htm ... herLicense

In short: If Jon as copyright holder of JSBSim says it's okay to use JSBSim for software under a different license, then there is no issue. JSBSim still remains available for us under GPL, end of story.
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Re: GPL or not GPL ?

Postby Hooray » Mon Jun 18, 2012 9:44 am

Ummm, JSBSim is LGPL
The LGPL is all about allowing people to link in LIBRARY code, without having the same viral effects that the GPL has: http://en.wikipedia.org/wiki/GNU_Lesser ... ic_License
And you CAN use even GPL'ed software in proprietary (closed source) programs safely, as long as you use existing interfaces (or share any modifications) and all "coupling" takes place at an arm's length. JSBSim uses the FG/SG property tree for most of its internal state - as such, it's fairly easy not to rely on the GPL or the LGPL, so that no license is violated.


PS:
Finally, you know. It is also required for any project using all or part of GPL code to be GPL also.

That's also wrong.
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Re: GPL or not GPL ?

Postby helijah » Mon Jun 18, 2012 10:04 am

OK. Totally agree. But for me LGPL is a abhération in the world of GPL.
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Re: GPL or not GPL ?

Postby Hooray » Mon Jun 18, 2012 10:16 am

That's not the point, it's another discussion - and it's not really our business: The LGPL is there for a reason. The viral nature of the GPL is a huge problem for many proprietary projects.
If a software developer decides to license his work under the LGPL, it's fine - and if you don't agree with the LGPL, simply stop contributing to LGPL'ed projects.
Obviously, you need to understand all the implications first.
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Re: GPL or not GPL ?

Postby helijah » Mon Jun 18, 2012 10:50 am

Hooray wrote in Mon Jun 18, 2012 10:16 am:That's not the point, it's another discussion - and it's not really our business: The LGPL is there for a reason. The viral nature of the GPL is a huge problem for many proprietary projects.
If a software developer decides to license his work under the LGPL, it's fine - and if you don't agree with the LGPL, simply stop contributing to LGPL'ed projects.
Obviously, you need to understand all the implications first.


I totally agree, but through my FG contribions I also contributes (constrained and forced) to JSBSim and thus a LGPL license. And I will not stop FG for that . FG is GPL ! Like what all this is not so easy!

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Re: GPL or not GPL ?

Postby mr_no » Mon Jun 18, 2012 11:26 am

This starts another question:
Should FG rendering migrate to Proland?
It's GPL3 and it would save a lot of time for developers.
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Re: GPL or not GPL ?

Postby Thorsten » Mon Jun 18, 2012 12:09 pm

I totally agree, but through my FG contribions I also contributes (constrained and forced) to JSBSim and thus a LGPL license.


Huh? JSBSim and 3d modelling and aircraft building are two building blocks of Flightgear, so while both you and JSBSim contribute to Flightgear, you do not contribute to JSBSim.

This starts another question:
Should FG rendering migrate to Proland?
It's GPL3 and it would save a lot of time for developers.


After thinking about it, I'm not sure if comparison between rendering engines based on gallery screenshots isn't largely a red herring.

Flightgear rendering can be made to look spectacular with photorealistic texturing and 10 m linear resolution for elevation data. The problem in reality is not so much the rendering engine but simply the data. We don't have free hires GPL compatible photographs or hires elevation data for the world. If you use another rendering engine to render the world data we have, it wouldn't look much different from how it looks now. Unless you go for dynamical generation of detail - which is a completely different philosophy and highly controversial (see the discussion surrounding the gradient shaders). Also, the question is - how fast does it run in practice?

Personally, Flightgear moving to a different rendering engine would see me moving to a different hobby - I don't want to start from scratch building a new environment simulation. Rather than saving a lot of time, it would cost a lot of time to learn everything anew.
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Re: GPL or not GPL ?

Postby mr_no » Mon Jun 18, 2012 1:15 pm

Judging from the videos it looked like a plug-in possibility.
Also the scenery editing is enormously easier.
But, I understand that it isn't that easy and it would bring forward another set of problems.
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Re: GPL or not GPL ?

Postby helijah » Mon Jun 18, 2012 1:20 pm

Thorsten wrote in Mon Jun 18, 2012 12:09 pm:Huh? JSBSim and 3d modelling and aircraft building are two building blocks of Flightgear, so while both you and JSBSim contribute to Flightgear, you do not contribute to JSBSim.


This is true, without an airplane it is easy to create flight models and test flight! It is a thoughtless remark !

Thorsten wrote in Mon Jun 18, 2012 12:09 pm:After thinking about it, I'm not sure if comparison between rendering engines based on gallery screenshots isn't largely a red herring.


How dare to question open source work with as a reference only pictures? There are also videos and especially the sources are available and a different API documentation is also available. Also my goal was not to expect to see Proland in FG. But just to make it known. For if Outerra is closed, Proland it is completely open.

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Re: GPL or not GPL ?

Postby Thorsten » Mon Jun 18, 2012 1:32 pm

How dare to question open source work with as a reference only pictures?


At this point, I'm willing to attribute the tone of this remark to language issues. Naturally, you are not in any position to tell me what I would dare and what not.

There are also videos and especially the sources are available and a different API documentation is also available.


So what? Does the documentation tell me how fast it would render Flightgear or how our scenery would look rendered? I think rather not.

Also my goal was not to expect to see Proland in FG


Did it occur to you that my reply wasn't at you?
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Re: GPL or not GPL ?

Postby helijah » Mon Jun 18, 2012 2:46 pm

Thorsten wrote in Mon Jun 18, 2012 1:32 pm:At this point, I'm willing to attribute the tone of this remark to language issues. Naturally, you are not in any position to tell me what I would dare and what not.


It's true, I don't know read!
Thorsten wrote:After thinking about it, I'm not sure if comparison between rendering engines based on gallery screenshots isn't largely a red herring.

It is not complicated to understand ! But maybe it is you who has forgotten something in your sentence. This is possible. Unfortunately I'm not clairvoyant and I can not know what's in your head :)

Thorsten wrote in Mon Jun 18, 2012 1:32 pm:So what? Does the documentation tell me how fast it would render Flightgear or how our scenery would look rendered? I think rather not.


You think? All right. But believing is not proof. It is best to do tests before give advice. Personally, I present something I discovered. Nothing more.

Thorsten wrote in Mon Jun 18, 2012 1:32 pm:Did it occur to you that my reply wasn't at you?


My comment was for mr_no not for you lol
mr_no wrote:Should FG rendering migrate to Proland?


Regards Emmanuel
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Re: GPL or not GPL ?

Postby mr_no » Mon Jun 18, 2012 4:23 pm

Thorsten, you did make a fast conclusion that I based my opinion on images alone, but I even watched videos of the scenery editor.

The conclusions that we can make from those are that we need denser forests with 3d tree models that cast shadows.
We also need collision with trees. This all in the future because the performance impact is surely big.

This scenery editing today is IMHO impossibly hard. Of course we can't create any ground surface but the one based on a realistic data. That Proland scenery editor would make it easier to create roads and what not, but especially airports.
Its impressive because it's easy as a 3D modelling software but it has road textures, just like the ones that are being developed for FG. Also when you create a road it's not tilted but horizontal etc.

My thoughts were just around reducing the workload for future developments here, but I know that the difference isn't that big.
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Re: GPL or not GPL ?

Postby Hooray » Mon Jun 18, 2012 6:57 pm

This is true, without an airplane it is easy to create flight models and test flight! It is a thoughtless remark !


What Thorsten probably was saying is that no "data" contributions are relevant in the context of the JSBSim project being LGPL, obviously the source code and binary linking are important here - not the license of some artwork or aircraft/FDM configuration files.

No matter if you are looking at screen shots or "even" videos: None of this will tell you if you can integrate ProLand into FG. You will not just need to look at the APIs of ProLand, but you'll first of all need to understand how OSG works and how it is used in FlightGear.

Don't get me wrong, it's great that there's a "GPL'ed Outerra" project there - but if you want to see it used in FlightGear, there are much better ways to discuss and prepare this.

At the moment, it's just obvious that there mainly people here requesting something to be added, just based on screen shots and videos, without them having ever written any OpenGL/OSG C++ code - so all that can be said, is that you'd like to see the features depicted in the screen shots and videos - but don't just throw buzzwords like "API" around.

To make a different OSS project work with (inside) FlightGear, you need to follow the OSG protocols - no matter if it's OSGOcean, PixelCity or Sumo.

Otherwise, you would need to favor a standalone/interfacing approach, where separate tools communicate with FlightGear using the property tree.
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Re: GPL or not GPL ?

Postby Thorsten » Mon Jun 18, 2012 7:00 pm

The conclusions that we can make from those are that we need denser forests with 3d tree models that cast shadows.


We can have that now - if you're willing to fly with 5 fps or get a really powerful system... It's not that Flightgear wouldn't have the technology, it's just not fast enough.

This scenery editing today is IMHO impossibly hard. Of course we can't create any ground surface but the one based on a realistic data. That Proland scenery editor would make it easier to create roads and what not, but especially airports.


I've said this elsewhere: Ease of manual scenery editing is way down the priority list. Even if all forum members would start to edit scenery manually tomorrow and continue it for a year, it wouldn't make a big impact on a world scenery, just barely on a small country. The current scheme allows to convert large amounts of geodata to scenery automatically and to utilize lots of computing power to do so, which is what matters.

Also when you create a road it's not tilted but horizontal etc.


All a matter of quality data and performance impact you're willing to tolerate. Italy custom scenery has creeks precisely down in the valley floor and roads winding nicely up the mountains - and that comes with a really impressive vertex count driving framerates down because you need plenty of vertices to create smoothly curving roads.

My thoughts were just around reducing the workload for future developments here, but I know that the difference isn't that big.


Lots of flightgear functionality rely on the terrain being identified as a landclass, so we don't just paint and texture a mesh, we know what the terrain underneath is. Can a different scheme deliver this functionality? Just the first of several questions which come to my mind. I don't think it's anywhere close to a matter of 'plugging something in'.
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