Some notes beforehand:
- Insulting others in relation to licensing matters may result in an immediate one week forum ban.
- This post is in NO way a legally binding text, it is NOT an addendum/exception to the GNU GPL.
- This post is only a clarification of an opinion a number of Spring developers share.
- This post does not oblige us to take action against those not respecting this opinion.
There have been various discussions on these forums on how and why the engine's GNU GPL would affect content for the engine. During this time everyone has formed his or her opinion on this, and these opinions tend to differ a lot, up to the point the discussions turned into flamewars and ragequits.
This post is meant to alleviate this, by giving some clarification on how we, Spring engine developers, think the GNU GPL applies to content for the Spring engine.
- We think a package of content for Spring (e.g. sdz, sd7) is not a "single work" derived of the engine in the terms of the GPL. A package of content may consist of multiple (independent) works, each of which may be covered by a different license. (The licenses must be compatible of course.)
- We believe generally all LUA, COB, BOS scripts are "linking" to the engine, to speak in the terms of the GPL again. In practice this means many LUA, COB and BOS scripts need to be licensed under the terms of the GNU GPL.
- There are no plans to add an exception to the engine's license in the foreseeable future to change this.
- All other content in a package can be licensed however you want. (models, textures, sound, music, icons, etc.)
This implies (not necessarily complete) for example:
- Gadgets, widgets, and other Spring related LUA scripts should generally be freely reusable between games, mods and maps. Utility LUAs (e.g. some data structure you found on http://lua-users.org/) are of course an exception, these may have their own license terms attached.
- Just because a game/mod uses LUA, this does NOT mean you may steal art from the game/mod because supposedly the art "is infected by the GPL". We think the art may be covered by a different license. This also generally means you can not distribute a modified copy of a game/mod without asking the author, unless there's some note/license inside which allows this.
We hope this clarifies the situation for all involved with Spring, and remember it's appropriate to always speak with the developer of anything before using it!
PS. Of course we, developers, do not all have the same opinion. The opinion that LUA/COB/BOS actually falls entirely outside the scope of the engine's license is also commonly present. We chose to put the strictest opinion here however just to be sure.
PPS. Licensing art under GPL is not only not required, but actually not really recommended, because GPL is designed for code, and not for art.
PPPS. Reactions can be posted here.