I have a shader that uses the Z rotation of an empty (called Sara_Origin) through drivers to calculate the shadows on the face. The empty's rotation is constrained to the head bone of the character using a Child Of constraint.
The problem is when rotating the head bone, the empty's rotation doesn't update since it's using a Child Of constraint. Rotating the empty itself works fine.
Is there a way to find the Z Euler rotation value of the empty after it has been rotated through the constraint?