Licenses

[Pureon]

This one seems to use CC-BY-SA 2.0. Same as the above - we need to find out whether it is compatible.

Taking a quick look now, I found this on creativecommons.org:

The CC-BY-SA licenses are such that content under a version 2.0 cannot be used under the terms of CC-BY-SA 3.0. That means a derivative of a CC BY-SA 2.0 work cannot wholly be released under CC BY-SA 3.0. The same thing could happen between BY-SA 3.0 and 4.0.

From: http://wiki.creativecommons.org/4.0/Treatment_of_adaptations

[zoot]

Taking a quick look now, I found this on creativecommons.org:

Right. So to use that image, it would probably be necessary to contact that author and ask if he could kindly make it available under CC-BY-SA 3.0.

Edited August 13, 2012 by zoot

[fabio]

It should be compatible only when the term "licensed under XXX or a later version" is available. This term is usually suggested to add, to avoid to be stopped by a license than later reveals some issues.

[zoot]

It should be compatible only when the term "licensed under XXX or a later version" is available. This term is usually suggested to add, to avoid to be stopped by a license than later reveals some issues.

Two completely different licenses can be compatible (e.g. BSD code can be used in a GPL program), so it is a bit less straightforward than that.

[majapahit]

Somebody should create "easy to understand" license for future long term use.

[myconid]

Surely, textures created by Wildfire games are under CC-BY-SA 3.0, but that doesn't mean that textures from other sources need to be re-licensed to be used in the project. We might not need to contact the authors unless we want to change the license of something from whatever incompatible CC version to CC-BY-SA 3.0.

What I'm trying to say is, there's probably no problem as long as we honour the original licenses of the images. If for instance, an image is CC-BY-SA 2.0, we'll need to have somewhere that says we're redistributing that image under CC-BY-SA 2.0, not CC-BY-SA 3.0, and here's the link to the 2.0 license and here's the author's attribution.

Afaik, there's no issue with mixing different-licensed textures on the same model, just like there's no issue with mixing various different-licensed images in a Wikipedia article with GPLed text.

But yeah, something like this sounds too reasonable, so I must be wrong.

Better ask a lawyer to be sure.

[zoot]

You're absolutely right, there is no issue in that. However, art/LICENSE.txt states:

The files in this directory are Copyright © 2009 Wildfire Games. These files are licensed under the Creative Commons Attribution-Share Alike 3.0

(CC-by-sa) license, available at http://creativecommons.org/licenses/by-sa/3.0/

So if the strategy you are proposing is pursued, at least that bit of legalese needs to be revised.

[myconid]

So if the strategy you are proposing is pursued, at least that bit of legalese needs to be revised.

That needs to happen anyway - that's the whole point of attribution/sharealike.

[zoot]

That needs to happen anyway - that's the whole point of asking for attribution.

Not sure what you mean by that, but my point was more that the LICENSE.txt suggests that the team has previously wanted to be able release everything under CC-BY-SA 3.0 (which IMO would be nice, but perhaps not strictly necessary). Releasing art under multiple licenses would require a change of that strategy (that the relevant people would need to agree to).

[myconid]

I mean the whole point of CC licenses is that you change your LICENSE.txt file a little and that's it. Credit goes where it's due and everybody's happy.

[zoot]

Credit could be given in a separate file as suggested here, but I don't really dispute everyone will be happy in the end

Edited August 17, 2012 by zoot

[myconid]

Yeah, that works.

Another thing to think about is the licensing of elements in texture "atlases", where you combine several textures into a mega-texture like the roman_struct one. Maybe there needs to be an annotation system with little numbers in the margins or something (I doubt there'll be too many images that we can't create ourselves or can't find public domain versions of, so something like this won't get in the way too much).

[zoot]

As far as attribution goes, I believe it is generally sufficient just to state "I used this dude's texture" somewhere reasonably prominent, without necessarily linking it to the exact texture in question. For keeping track of the sources of textures internally, perhaps just a 'file' on this forum would work - unless one wants to include it in the release for the sake of tidyness/completeness.

[myconid]

Yup, that looks sufficient. Further reading: http://wiki.creative...g/Marking/Users

Alternative licensing blurb for LICENSE.txt could be (according to CC website):

Except otherwise noted, the files in this directory are Copyright © 2009 Wildfire Games. These files are licensed under the Creative Commons Attribution-Share Alike 3.0(CC-by-sa) license, available at http://creativecommo...nses/by-sa/3.0/.

[fabio]

Note that only the 3.0 version of CC-BY-SA is Debian compatible. What does that mean? That 0 A.D. may be removed from Debian (and other distributions, especially the ones derived from it, like Ubuntu) or that the incompatible files be removed and 0ad repackages without those (see the many Debian packages with +dfsg version suffix).

[zoot]

Note that only the 3.0 version of CC-BY-SA is Debian compatible. What does that mean? That 0 A.D. may be removed from Debian (and other distributions, especially the ones derived from it, like Ubuntu) or that the incompatible files be removed and 0ad repackages without those (see the many Debian packages with +dfsg version suffix).

Very good point. I hope we can avoid non-CC-BY-SA 3.0 textures, then.

[myconid]

Note that only the 3.0 version of CC-BY-SA is Debian compatible. What does that mean? That 0 A.D. may be removed from Debian (and other distributions, especially the ones derived from it, like Ubuntu) or that the incompatible files be removed and 0ad repackages without those (see the many Debian packages with +dfsg version suffix).

They'll have a heart attack when they see the textures from CGTextures.

[zoot]

They'll have a heart attack when they see the textures from CGTextures.

We have permission to relicense those, though, right? (Though the blurb doesn't state the version number of the CC-BY-SA we are allowed to use - that ought to be cleared up too.)

[myconid]

So to summarise so far:

- If possible, we should stick to CC-BY-SA 3.0 or public domain images from outside sources like Wikipedia.

- CC-BY-SA < 3.0 may have problems with Debian's DFSG, so we'd need to contact the author to relicense under CC-BY-SA 3.0. It looks like CC-BY is mostly okay (accepted in the repos, but still kind of a grey area).

- CC-BY-SA 3.0 images not made by us require attribution, so the details need to be stated in a text file, like gudo suggested.

[zoot]

Yup! And I would add:

- Someone needs to update the copyright blurb in art/LICENSE.txt as suggested here.

- Someone needs to ascertain that we are allowed to redistribute CGTextures under CC-BY-SA 3.0 (and not some other version) and update art/LICENSE.txt accordingly.

- There seems to be a huge backlog of textures whose provenance is unknown and therefore may be illegal to redistribute; someone needs to determine how this should be dealt with.

Edited August 18, 2012 by zoot

[fabio]

I also really suggest to always use the "or any later version" clause to both GPL code and CC-BY-SA artwork. Licenses have to adapt to change in laws, no surprire both licenses are currently at their 3rd major version. If you later need to update, to e.g., CC-BY-SA 4.0, you should contact all authors again to relicense, spent a lot of time in it, or rewrite/drop the code and it may take years. I see a lot of problems related to these, but I'll just link to this interesting story related to the "or later" clause since I was the first to report the problem. The downside is that you need to trust an unreleased license that you may not fully agree, but I think that this a relatively minor problem, which, for the GPL, is also addressed with this clause: "Later license versions may give you additional or different permissions. However, no additional obligations are imposed on any author or copyright holder as a result of your choosing to follow a later version." (see point 14 of GPLv3).

[zoot]

I also really suggest to always use the "or any later version" clause to both GPL code and CC-BY-SA artwork. Licenses have to adapt to change in laws, no surprire both licenses are currently at their 3rd major version. If you later need to update, to e.g., CC-BY-SA 4.0, you should contact all authors again to relicense, spent a lot of time in it, or rewrite/drop the code and it may take years. I see a lot of problems related to these, but I'll just link to this interesting story related to the "or later" clause since I was the first to report the problem. The downside is that you need to trust an unreleased license that you may not fully agree, but I think that this a relatively minor problem, which, for the GPL, is also addressed with this clause: "Later license versions may give you additional or different permissions. However, no additional obligations are imposed on any author or copyright holder as a result of your choosing to follow a later version." (see point 14 of GPLv3).

I agree, that would make some sense (though I think we'd need a lawyer to formulate it). The clause is inherent to the GPL, though (as you note), so it is an issue specific to CC-BY-SA content.

[fabio]

It looks that the "or later" clause is not needed for CC-BY-SA >= 2.0 license:

http://wiki.creativecommons.org/Frequently_Asked_Questions#Which_Creative_Commons_ShareAlike_license_versions_are_compatible_with_each_other.3F

http://wiki.creativecommons.org/License_versions#Compatible_licenses_may_be_used_for_adaptations_of_works_originally_offered_under_CC_ShareAlike_licenses

However they speak only of adaptations, so I don't know if the unmodified art can be released to a newer license.

[zoot]

It looks that the "or later" clause is not needed for CC-BY-SA >= 2.0 license:

http://wiki.creative...h_each_other.3F

http://wiki.creative...eAlike_licenses

However they speak only of adaptations, so I don't know if the unmodified art can be released to a newer license.

Further down, they state:

NOTE2: However, when a work under CC-BY-SA 2.0 is used to create an adaptation, and the adaptation is released under CC-BY-SA 3.0, it is not that the whole of the adaptation is usable under CC-BY-SA 3.0. It is more like a "blended" state of licenses - the parts of the adaptation inherited directly from the original work is usable under CC-BY-SA 2.0, and not under 3.0, whereas other parts of the adaptation is under CC-BY-SA 3.0. This is a direct consequence of not allowing sublicensing.

So, unlike in the case of the GPL, the original portion of a CC-BY-SA 3.0 work adapted from a CC-BY-SA 2.0 work would remain incompatible with e.g. the DFSG. I.e. we still need to avoid CC-BY-SA 2.0 content and content derived from it.

Edited August 18, 2012 by zoot

[fabio]

Good finding, the source of that is here.