Hello! I have a question, i am new to making blend shapes for a mesh and i am making a VRChat avatar in blender. I want to make a tail move very slightly whenever my avatar blinks or closes their eye. My question is, would it be possible to make the armature move whenever a blend shape key on the mesh is at full value? I want to be consistent with how much it moves and i think the best way would be to use a certain amount of rotation on some of the tail’s bones. Instead of, well… moving the vertices lol. Thank you for your time everyone.
You can copy-paste the shape key value as driver for bone’s rotation (in Pose mode). Remember to convert driver to Scripted expression to manipulate it with simple functions or Python expressions. In this example the Lattice’s shape key for eye blink drives the tail rotation to 1/8 of the key value (rotation in radiants). In some cases you may want to add a limit rotation constraint to the bone and the constraint can also depend on shape key value, there is no limit to what you can do with a basic understanding of drivers. Ignore the eye Bone in this specific example except you want to use transformation between bones (e.g. the second bone can rotate whenever the first one scales). I do not do any 3d that is why i used Grease Pencil but the principles are the same.
The drawback is that now you need to create different bones to fully rotate the tail and clear keyframes every time you need to edit the driver. On second thought maybe you should use Shape keys for both the blink and the movement of the tail and drive the second key with the first one’s value so you do not mess with the bones. I give a second example with just shape keys linked to each other
fox_drivers.blend (2.1 MB)
fox_shape_keys.blend (2.1 MB)