[cc-licenses] Use cases for cc by-sa compatibility with GPL
arne_bab at web.de
Thu Dec 22 09:41:38 EST 2011
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
1. Using already existing cultural works under GPL with content under cc by-sa (my personal use-case)
There already is quite a lot of GPL and cc by-sa content which cannot
be used together for purely legal reasons.
There is Battle for Wesnoth¹ with GPL licensed text and artwork, and
Ryzoom² with cc by-sa assets.
And (my case) there is my own free roleplaying game³ under GPL which
utilizes Wesnoth graphics but cannot use those from Ryzoom, even
though the Ryzoom folks freed their graphics with the intent of
allowing others to use them.
2. Using Python scripts in blender
This already came up, but I want to add some legal stuff.
In GPLv3, something is considered a derivative work, if there is
“intimate data communication”. In Python importing a GPL module always
makes your code a derivative work, so you have to use the GPL,
too. When you use a python script in blender and you adapt it to the
specifics of your model - for example the nature of your rig - the
model and the code have intimate data communication, so it is very
likely that you have to licence your model under a GPL compatible
Thought to the end, this could mean, that currently you are not allowed
to use cc by-sa with rigged blender models, when you use any kind of
¹: Blender Python-scripts seem to be GPL without exception, so plugins
have to be GPL, too. It would be nice if someone versed in legalities
could check that:
3. Using content from free software in artworks
Currently you cannot make cc by-sa licensed artwork which uses GPL
works - and be it only a snippet of code.
If cc by-sa allowed usage with GPL code, then the resulting work would
have to be GPL, but the new assets could be licensed under cc by-sa.
4. Not restricting the design of programs with legal details
Many people argue, that you can just separate artwork from the code.
This means, however, that the licensing restricts the structure of the
program. For example blender would have to disallow scripts embedded
in .blend files, if the model is not under a GPL-compatible
license. And embedded scripts are too convenient to lose them due to
(no time to write more - I hope these help as illustration)
PS: Even though the Free Software Foundation deems art as
non-functional, I strongly disagree. Art is just as functional as
code, it just works through pathways which are harder to assess. 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”?
Art is functional. It just not necessarily runs on a computer, but on
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