[Bf-committers] Some Ideas for a Blender Plugin System

Sybren A. Stüvel sybren at stuvel.eu
Tue Nov 3 15:14:53 CET 2015

Hi all,

On Sun, Nov 01, 2015 at 04:11:54PM +0100, Martin Felke wrote:
> Hi, today i was thinking a bit about possible approaches on how to
> add a C / C++ Plugin system to blender.

There seems to be a thing missing: a good overview of the pros and
cons of having a C/C++ plugin system at all.

> - dynamic compilation of module sources via Python / CFFI or LLVM,
> as in OSL Nodes

Help me understand - how is this going to work, when most 3D artists
don't have a compiler installed? Are we going to ship Blender with a

> - source distribution of plugins is C / C++  + some py Wrapper for
> autocompile or binary distribution in case no compiler is present

So you want to ship binaries as well? Then why bother with
autocompilation? Or is that only used while developing plugins?

On Mon, Nov 02, 2015 at 10:06:08PM +0100, matmenu wrote:
> Sounds really good and needed as reality showed that being GPL is
> not enough to make adding functionality easy. Looks also like all
> devs loose to much time reviewing, so c/c++ plugins are a really
> good solution to avoid so many modifiers die in the patch tracker or
> be limited to some custom builds like in past year.

Then again, creating a good plugin system is not easy, so that too
will take up developers time, which would otherwise be put into
feature development and bug fixing. Furthermore, creating and
maintaining an accurate dependency graph of the plugins will also take
time (and we'll forget to maintain those, causing bugs).

All in all I can see a few cons:

- Blender will become more complex, as not only its functionality
  needs to be maintained, but also the "plumbing" required for the
  plugin system.

- Development will become more complex, as different permutations of
  loaded/unloaded plugins have to be tested.

- Mistakes in a C/C++ plugin can cause all kinds of crashes of Blender
  itself. In contrast, an exception in a Python script is relatively
  easy to catch & handle without sacrificing Blender's stability.

- Compilation of the code into libraries is difficult, as it is very
  unlikely that all plugin developers will have access to all OSses
  that Blender runs on.

Sorry for this depressing post, but I think we should discuss whether
we want such a plugin system at all, before diving into the specifics.

Sybren A. Stüvel


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