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Boder

zlib license: what are my restrictions

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I'm working on a project that is based on a game released under the zlib license. I have a few steps. 1. Convert roughly 75% of the C++ code to python 2. Convert the lua scripts to python 3. Change or enhance some of the art 4. Add media 5. From there make many modifications 6. Release This is non-commercial. Are there any license restrictions on the python code I write? The code will have some of the same identifiers and uses the same libraries mostly. Mainly dealing with #3, do I have to include the zlib license for unmodified and modified art/data?

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I'm not sure if you mean #3 from your post, or #3 from the license. Both of them are closely related.

The license itself is simple enough. It says:

Quote:
This software is provided 'as-is', without any express or implied warranty. In no event will the authors be held liable for any damages arising from the use of this software.
That means that you are using it from them and understand that it might be broken. Sounds like you've accepted that.
Quote:
Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions:
So basically it applies to you.

They permit you to create deriviative works, redistribute them, and use it for any other purpose you want, as long as you follow their three simple rules. Follow their rules. That's quite generous.

Note, however, that it applies to the software, and last time I checked, images are generally not considered software.
Quote:
1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
Easy enough. Say it is your own product. Don't mention their original stuff. Or if you want to, say something like "based on Foomatic by BarSoft."
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2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
Again, quite easy. You can't say "This is the original Foomatic by BarSoft."
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3. This notice may not be removed or altered from any source distribution.
So this is the part you don't like?

If you aren't distributing your source code, then there is no problem. Your non-source distributions are completely unencumbered.

If you are distributing your source code, then source files containing that specific license cannot have it removed or altered. Note that zlib places the license inside their two source files directly, so this is not an issue for them. If the authors of your source stuff embedded the license directly in their source files, then it applies to those files.

Personally, I would place that license in your new files. I can't state for certain if you would be okay by omitting the license in your completely different file that is based on theirs. You are creating a derivative work and so you are bound to accept their terms for copyright reasons. And it is also clear that if you incorporate their source into a work, their work must retain their notice. With just those two facts, I would think that your code that is directly derived from theirs must fall in to that category.


Artwork is a more sticky issue.

By using that particular license for art, it is clear they didn't consult with a lawyer on the matter.

Did they embed this license in every file of their artwork? If so, then the artwork is properly licensed and you shouldn't remove the embedded text when you edit images.

Unless you want to argue that images are not source, which many people have done. If they didn't include the license specifically for the images, you must wonder if the images are actually covered under the license. In that situation, you cannot use the images under the granted license.


By using that license, unless they actually embedded the license into the images, they have put themselves into a legally gray area.


It sounds like you aleady know that for any legal issue you should contact a real live lawyer and discuss IP rights with them in depth.


The best and easiest solution in this case is to contact the authors and ask them about it. If you did talk to a lawyer, they would tell you this single, easy step: Get written permission to use the source code and images free of ALL restrictions.

If they can't or won't, try to get written permission to use the images under some other license that coveres binary non-source data. If restriction #3 for source is a concern, try to get them to remove that restriction for you.



As always:
* the fact that it is non-commercial makes no difference.
* talk to a lawyer for actual legal advice.

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I have contacted the person a few weeks ago, so I know he is a nice guy and we can work it out.

But on the theoretical side, I never realized that if you created a derivative work and released it under the GPL, you still have to include the zlib license? It seems pretty clear in the requirements, if source distribution refers to all modified source code. So only the modified portions would be covered under GPL, the rest is still zlib, but it doesn't really matter because if you want to use the alterations then you would have to accept the GPL.

Now that we see the zlib license isn't good for images, is the GPL any better? I might try to lobby the project lead (of a different project) to change the license.

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Quote:
Original post by Boder
I have contacted the person a few weeks ago, so I know he is a nice guy and we can work it out.
Excellent! That's always the best route.

Quote:
Original post by Boder
But on the theoretical side, I never realized that if you created a derivative work and released it under the GPL, you still have to include the zlib license?

When did GPL enter the discussion?

Quote:
Original post by Boder
So only the modified portions would be covered under GPL, the rest is still zlib, but it doesn't really matter because if you want to use the alterations then you would have to accept the GPL.
The zlib license specifically grants you permission to alter and redistribute it, (altering includes derivative works) ONLY on the condition that you leave that notice, unaltered, in the source.

The GPL is a completely different license with a completely different set of requirements. That license is compatible with the GPL-3 license thanks to its section 7. In other words, you can incorporate zlib licensed source into a GPL licensed work because both GPL3 and zlib licenses allow it

Note that by doing so you are not removing it from the zlib license. It continues to have the zlib license around it.

In order to use the version released under GPL and zlib, the next person in the chain must follow BOTH licenses.

Quote:
Original post by Boder
Now that we see the zlib license isn't good for images, is the GPL any better?

No.

The GPL is intended to be used on software only. It calls the work "The Program", it talks about "Source Code", "Object Code", "System Libraries", and so on.

If you look at artwork from GNU's GNOME, they are nearly all covered under various Creative Commons licenses. Many of these licenses ARE designed for images, audio, video, and other formats.
Quote:
I might try to lobby the project lead (of a different project) to change the license.

That is up to you. I would suggest that an IP lawyer is involved.

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You last remark is actually quite humorous in the situation. The project in question began as a "clone" of Super Mario Brothers, which, even though the code was properly GPL, stepped on the toes of trademark and copyright law.

Now considerable effort continues to clear the project of its past murky waters.

Strangely enough, it is the 3rd and 4th hit of a google for "mario clone" even though it only mentions mario once!

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