Use bones of face rig instead of shape keys (rigify)

Question

With the new blender pose library, I would like to add my armature with facial expressions. However, I have created a character in Character Creator 4.

When importing this character in blender, the character has a lot of bones in it's face. There are also some presets of emitions I can use. However, they are not being used when animating the face, but instead it uses shape keys. The problem is that shape keys cannot be added to the pose library in blender 4.0, so I would like to convert these shape keys to bones.

Is there a way to convert these shape keys to the already exsisting bones?

I can always animate the face manually and add it to the pose library, but I guess there should be a better/faster way to do so. Thanks in advance!

Answer 1

Rigify has nothing to do with your model's shapekeys, that's what your model came with, Rigify doesn't handle them.

That being said, if you want to have them in your pose library, the way to go is to add controls in your rig to handle them.
Because what's available in your pose asset is what the "action data block" can access to. And each object having its own Action, that's why you can't have a mesh object's shapekeys keyframes in an armature pose's keyframes: they aren't in the same place.

To fix this, you can add a bone somewhere in that rig (or use one that's already there), and create custom bone properties on that bone that control the shapekeys.

1. Go in your Armature in Pose mode and select the bone you want to control the shapekeys with.
2. In Properties Editor > Bone Data Tab > Custom Properties panel, create a custom properties and use the gear icon to set its name, min/max values, default (usually zero), and enable "Library Overridable".
   
3. Back in the panel, RMB the property value > Copy as New Driver
4. Select the mesh object in Object Mode
5. In Properties Editor > Mesh Data tab > Shape Keys Panel, RMB a shapekey > Paste as new driver

From then on, when you want to animate that shapekey, use the bone's custom property, you can access it from the viewport sidebar as well.

This probably can be made into a script to be done faster.