[Bf-committers] extension clause

Campbell Barton ideasman42 at gmail.com
Mon Nov 22 06:05:09 CET 2010

On Mon, Nov 22, 2010 at 3:56 AM, Alex Combas <blenderwell at gmail.com> wrote:
> On Sun, Nov 21, 2010 at 3:30 PM, Dan Eicher <dan at trollwerks.org> wrote:
>> >
>> > For
>> > example, if I made an interesting game using the Blender Game Engine, I
>> > could sell my game as a binary with my only obligation to release the
>> > source
>> > to all components of the Blender Game Engine I used, as well as any
>> > improvements or changes I made to that code. My game-code could remain
>> > closed and sold as a for-profit binary.
>> >
>> > You can do that now, your python code can be licensed how you please and
>> art assets are protected by standard copyright law.
> I think you are wrong here.
> Only if your Python code is just a simply script which only calls Blenders
> built in Python
> Interpreter you can license it however you please.
> However if your Python code links to _ANY_ compiled binary, even a compiled
> binary which
> you yourself wrote... then your Python script is considered to be
> "extending" Blender, and thus
> your script and your compiled binary must be licensed as GPL if you want to
> distribute them
> in any way.

While this is what blenders GPL exception states it does seem quite
fuzzy as to what it does/doesn't apply to.
- python its self has many compiled extensions, ok so it
cant/shouldn't apply to this case but where does it end?
- what if the extension loads a module such as PIL, numpy, or
PyGame???, I'm not sure in this case..
- what if you write your own module but make it BSD/GPL/Apache and
have it as a package which can be installed by debian's package
manager for eg.

So I'm guessing this is how it works...
- You can write your own BSD module and include no problems - since
this is what we do with python.
- You can write your own GPL module as long as you include the same
exception that blender its self has.
- You CAN'T make use of a 3rd party GPL module unless they make the
same allowances that blender does.

Our exception should be more clear about this. Saying you cant link to
compiled code of own license is too vague.

from: http://www.blender.org/education-help/faq/gpl-for-artists/
Not OK is:
Author publishes a Blender script, calling a compiled C library with
own code, both under own license.

This example could be elaborated to account for 'own license' for
python script, but GPL compatible license for compiled code, which as
far as I can tell should be acceptable.

- Campbell

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