This feature request is more coming from Maya and in my opinion, lack of this feature is limiting the facial rigging in blender. Currently, you can change the shape of mesh B and connect it to mesh A as shape key. Now if you change the shape of mesh B, shape of the mesh A doesn’t update in viewport.
In Maya, you can skin a mesh B to a skeleton and connect it to mesh A as shape key. Now if, you move joints on mesh B, it changes shape of the mesh A and updates it in viewport. This functionality allows the rigger to divide the face into separate parts which results in creating a very flexible setup for face. You can also apply other type of modifier on the mesh B too.
This functionality or updating the main mesh while the shape keys being updated using armature is missing from the blender. It restricts the rigger and makes it harder to create a setup using bones and shape keys which is animation friendly.
totally agree, I was looking around if there is any way to achieve this. This would make the rigging process more interactive and artist friendly… instead of guessing what certain shapes will do when combining them with others.
So did you found a way to achieve it?
Nope, there is no way to do this just like that. Maya is node-based and even on a user level you can manually plug anything anywhere in the software. We dont have such access in Blender so there is no implemented way we can feed shape keys live to a master mesh.
But at least I found some shape key related addons which improves the overall workflow, at least by being able to mirror shape keys and drives and keep everything tidy with just a few clicks.
I guess shape keys would need to become a modifier in order to get live updates (since they’re a deformer in Maya as well, rather than mesh data)
Another more achievable thing would be for shape keys not to be dependent on vert count but vert numbers. Working on heads rather than a full body and blending it back in the final rig is super common.