[Bf-committers] GPL: how to link with non-gpl plugins

Ton Roosendaal ton at blender.org
Thu May 17 13:19:02 CEST 2007


This is an issue that keeps coming back, especially with Blender  
becoming more interesting for commercial expoitation. For example; we  
are examining how a closed source renderer like Mental Ray could link  
to Blender.

Here's an interesting answer from the FSF in a similar case with  

Q: If a program released under the GPL uses a library that is LGPL, and  
this library can dlopen plug-ins at runtime, what are the requirements  
for the license of the plug-in ?

A: You may not distribute the plug-in with the GPL application.  
Distributing the plug-in alone, with the knowledge that it will be used  
primarily by GPL software is a bit of an edge case. We will not advise  
you that it would be safe to do so, but we also will not advise you  
that it would be absolutely forbidden.

Conclusion, the restriction is mostly on the distribution side. It  
could mean we can ask a company that makes a closed renderer for  

- to develop a non-functional LGPL wrapper for their product
- to develop an LGPL lightweight renderer with 100% identical API as  
the closed renderer.

In the latter case it's even more interesting for everyone, then you  
can see at least some of their work in an open license. :)
In both cases we can distribute code and binaries without violating the  

Is this correct to officially communicate? Please advise,


Ton Roosendaal  Blender Foundation ton at blender.org  


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