OGRE is released under an open source license. The license which applies depends on which version you’re using:
OGRE 1.7 and later – MIT
Ogre is released under the MIT License, which is a permissive open source license. The only condition is that you distribute the license text included in our distribution with any software that uses OGRE.
Older Versions – LGPL
This section only applies if you’re using OGRE 1.6 or earlier
Ogre’s default license is the GNU Lesser Public License (LGPL), with some exclusions (see below). This basically means that you can get the full source code for nothing, so long as you adhere to a few rules.
Under the LGPL you may use Ogre for any purpose you wish, and modify it if you require, as long as you:
- Pass on the (modified) Ogre source code with your software, with original copyrights intact
- If you distribute electronically, the source can be a separate download (either from your own site if you modified Ogre, or to this site if you used an unmodified version) – just include a link in your documentation
- If you distribute physical media, the Ogre source that you used to build your application should be included on that media
- Make it clear where you have customised it.
In addition to the LGPL license text, the following exceptions / clarifications to the LGPL conditions apply to OGRE:
- Making modifications to OGRE configuration files, build scripts and configuration headers such as OgreConfig.h in order to create a customised build setup of OGRE with the otherwise unmodified source code, does not constitute a derived work
- Building against OGRE headers which have inlined code does not constitute a derived work
- Code which subclasses OGRE classes outside of the OGRE libraries does not form a derived work
- From 1 March 2009, statically linking the OGRE libraries into a user application does not make the user application a derived work.
- Using source code obsfucation on the OGRE source code when distributing it is not permitted.
As per the terms of the LGPL, a “derived work” is one for which you have to distribute source code for, so when the clauses above define something as not a derived work, it means you don’t have to distribute source code for it. However, the original OGRE source code with all modifications must always be made available.
Alternative License (OUL)
For whatever reason some users feel that they cannot comply with, or would prefer not to comply with the conditions of the LGPL. Reasons might include:
- You wish to alter the OGRE core without releasing those changes publicly
- Despite the quite lenient conditions of the LGPL, you are constrained by licensing policies that prevent you using an open source license
To allow users with these issues to still consider using OGRE, an alternative license, the OGRE “Unrestricted” License (OUL), is available for a license fee. Thus users who have a specific need to avoid the conditions of the LGPL for their projects have the option of paying for a different license.