game screenshots with incompatibly licensed content

[Martin Erik Werner <martinerikwerner@gmail.com>]

Hi,

I'm involved in the game Red Eclipse[1], both in Debian and upstream.

We (upstream) were recently discussing including "art content" (in this
case a sky texture) licensed under the GPL (v2+ or v3 likely). (Yes, GPL
for art content is not a good idea in general, but that's a separate
issue.)

Red Eclipse currently includes a lot of art content licensed under the
CC-BY-SA-3.0 license, and as far as I have understood this license is
incompatible with the GPL license?
(https://www.gnu.org/licenses/license-list.html#ccbysa mentions only
version 2.0)

My impression is that using content under both licenses is fine in the
game itself, since it's dynamically used/displayed and not combined
otherwise.

However, what struck me as a problem here are screenshots, videos, etc.
showing the game and the art content in it. A screenshot showing both a
CC-BY-SA-3.0 texture and a GPL texture would be a derivative work of
both pieces of content, and in that case said screenshot would be
undistributable, since the licenses are incompatible.

Is this assumption correct? And should combinations of art content with
incompatible licenses in software that displays combinations of them, be
something to be wary about (when creating screenshots and similar) for
this reason?

The counsel regarding thumbnails in screenshots.d.n covered screenshots
and copyright in some aspects
http://wiki.debian.org/ScreenShots#License_of_screenshots
however it doesn't (I think) deal directly with this particular
question.


[1]
http://redeclipse.net
http://packages.qa.debian.org/r/redeclipse.html
http://packages.qa.debian.org/r/redeclipse-data.html
(redeclipse-data is non-free due to much of the art content missing
"sources" (by the same argument that PDF files can be non-free))

Thanks
-- 
Martin Erik Werner <martinerikwerner@gmail.com>