[Bf-blender-npr] Library linking for NPR workflow

[Light BWK]

Hi,

Referring to a post by Nathan Vegdahl about library linking on Blender Artists:
http://blenderartists.org/forum/showthread.php?334916-Blender-from-the-perspective-of-the-studio&p=2634150&viewfull=1#post2634150

He wrote:
"...There are some serious inherent limitations in Blender's library
linking system as it currently stands. Specifically, you can't tweak,
modify, or animate anything that's linked. The only exception is
animating armatures via the proxy system, but that's a quirky system
with plenty of issues of its own.

For what it's worth, we suffered a lot with the library linking system
on Sintel. Cloth sim on linked characters, hair sim on linked
characters, wanting to do shot-specific shape key tweaks, etc. We
managed to work around all of the issues, but they were quite
decidedly work-arounds/hacks and not good workflow. The "Blender way"
shouldn't be work-arounds and hacks by default."

In NPR workflow we are facing the same issue, but the limitation is
more obvious as the production starts to scale in complexity. In
freestyle alone, as discussed on this mailing list, current
implementation of library linking:

1. The inability to handle sub groups (without scripting and workarounds).
2. Don't import line style with mesh (Separate link/import).
3. Don't allow available data channels to be modified for quick 1
frame tweak/fix.

In NPR, we often fake lighting by animating shaders/materials. When
using linking, we totally lost the ability to change any setting. As
part of BEER's design, animating shader is a major feature and is
highly requested one. Before starting BEER coding, it is best that we
start looking into library linking issues.

There is a working design inside Blender that, I think, can solve
this. Shape-key has "basis" for the "zeroed/rest" state, then there is
almost unlimited channels to modify the data.

The common use cases with such feature in NPR workflow:
1. Fix Freestyle line glitch.
2. Animate freestyle settings.
3. Animate character's shaders when emotion changed.
4. Enhance/fake lighting on problematic surface for toon.
5. Animate shader's hue (often to intensify) on special condition
lighting, ie: a blinking red alert lamp.

I would love to hear more inputs on library linking in NPR workflow,
so that we can cover more use cases.


Best regards,

Light BWK
(Blender NPR team)