[cc-licenses] Use cases for cc by-sa compatibility with GPL

Arne Babenhauserheide arne_bab at web.de
Thu Dec 29 21:28:29 EST 2011

Hi Anthony, 

> On Thu, Dec 22, 2011 at 9:41 AM, Arne Babenhauserheide
> <arne_bab at web.de> wrote: 
> Hi,
> >
> > For me personally it is a huge problem that cc by-sa and GPL
> > cannot be used together in a combined work. That’s why I gathered
> > some use-cases for that.
> Well, they can if the combined work is a collection.  They also can
> if the authors of one of the works choose to dual-license it.

That’s a purely legal restriction on how the project can be organized,
and it’s pretty unsafe if the work is somewhat more complex than a

And you can’t get dual licensing, if the author cannot be found
because his email provider died. Or if there are hundreds of authors. 

Just changing Mercurial from GPLv2 only to GPLv2 or later took about
two years, because we had to find every author. Imagine the pain of
having to do that for dual licensing, where you actually have to
explain the other license.

> If the combined work is not a collection, well, that's the nature of
> sharealike.  You can't create a derivative work from a CC-BY-SA work
> which imposes extra restrictions.  That's not a bug, it's a feature.

Please tell that to the Ryzoom artists. Did they really intend to make
their art incompatible with the Wesnoth artwork?

Or did they not rather intend to make their artwork as widely usable
for copyleft projects as possible?

> > Great gameplay can crumble when you take away the music, and when
> > the gameplay is built around a narrative, it often needs the
> > narrative to realize its effect on the player. As a vicious
> > example: What would Mortal Combat be without someone shouting
> > “Finish him”?
> If the music or narrative or sound effects are that connected to the
> software, why are they CC-BY-SA in the first place?  Just license them
> as GPL.

Because I did not create that. I just found that great piece of free
culture artwork which inspired me, and I want to use it in a new game.

I don’t require that piece to be under GPL. I just want it to work
with my game engine without having to redesign the whole engine. And
then I have a blender script which is GPL, so I have to use GPL
there. And then I want to use some artwork with the model, so I have
to put it under GPL, too. And the same goes for all art which I
combine with the art. And shortly thereafter all artwork in my project
has to be GPL, so I cannot use any cc by-sa artwork, because I have a
slightly too strong code-art relationship.

All that, because cc by-sa does not allow using the art in GPL

GPL has the same goal as cc by-sa, just with a different
implementation, because the covered content exhibits different

Can you imagine the frustration of getting sued, because your artwork
is integrated too well with some code you just used while creating a
cool new level for some game?

Or because you integrated some snippet of Linux source code in your

If cc by-sa allowed using artwork in GPL projects, I could just
license all artwork under cc by-sa and all code under GPL, call my
project GPL with art under cc by-sa and not worry about licenses

And someone who wanted to distribute my project would just have to
check “do I comply with GPL?” and the rest would follow. 

After all, if someone complies to GPL, he automatically acts in the
spirit of cc by-sa, too.

> Unless you're saying that the music/narrative/sound effects were
> written without having the software in mind, 

Naturally that is the case! What’s the use of creating a free culture
licensing scheme which only works with the works I create myself?

> in which case I go back to my earlier point.  You can't create a
> derivative work from a CC-BY-SA work which imposes extra
> restrictions.  That's not a bug, it's a feature.

Just ask yourself: Did most cc by-sa users take the conscious decision
“I want to make sure that my art can only be used within game engines
which have strong seperation between code and art”?

Would an artist object to have their art reused in a blender model,
which is licensed under GPL, because it contains game engine AI

Does usage under GPL actually create an additional restriction, if you
consider the cc by-sa work be its own source?

Best wishes,

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