The majority of my question is identical to this one:
Cloth sim : collision with external linked group meshes
The OP found a workaround, so it was never really answered. I wasn't sure if there was a way to "reactivate" the question, hence my duplicate.
I have a rig that I created with the Rigify add-on (first time I've used it, and little experience with rigs in general). I believe I skinned & grouped it correctly, per the Humane Rigging videos. I linked it from a second blend file and made a proxy. I put a simple baggy robe mesh over the character mesh, with the intent of using the cloth simulation to make the robe flow properly as the character moves into the final position.
Here's where it gets tricky. I need to add a collision modifier to the character mesh - but where is it? It's not on the Outliner, and selecting it in the 3D View just selects the linked group. Some experimenting showed that I can make a separate proxy for the mesh, but it's not connected to the rig.
I thought the second answer on this post was a solution, but I couldn't get it to work; I'm not sure it would be any different than the mesh proxy I already tried:
How can I modify the mesh of a linked character?
Any ideas, pointers to videos or tutorials, etc., are greatly appreciated. I can post blend files if no one sees an obvious problem with what I'm doing.
[Update 1] I've created four simple blend files to demonstrate the problem. They're very simple, low-res examples to reduce the file size.
- char.blend - a simple 4-bone FK armature with a rough cylindrical shape.
- scene_appended.blend - a scene that appends char.blend, adds a collision modifier to the skin mesh, and drapes a cloth over it. This works as expected.
In char.blend, for linking via a group, I wasn't sure if I was supposed to include the mesh in the group, so I did it both ways.
- scene_linked-rig.blend - the same scene, but it links a group in char.blend containing just the armature (rig_group).
- scene_linked-rig-skin.blend - the same scene, but it links a group in char.blend containing the armature and the skin mesh (rig-skin_group).
With (3) and (4), I have no idea what to do, since I can't find the mesh in order to attach the collision modifier. I've tried all the combinations of "make local", "make single user", etc., that I can think of, but nothing seems to work.
[Update 2] Playing more with these simple files, I discovered that adding the collision modifier in char.blend works. Oddly, this didn't work with my real models. Unless I did something wrong. It's still not ideal, since I can't figure out how to change (or even find) the modifier in the scene if I need to.