ShapeKeySync.py

"""Shape key syncronization

* This script create drivers for shape keys in selected objects to reference the same named shape keys in the base object.

1. Select the objects for which you want to create drivers.
2. While holding the shift key, select the base object.
3. Run this script.
4. When you change any shape key of the base object, the corresponding shape key in the other objects will follow!

* Disclaimer: This script is provided "as is" without any warranties. 
              Use it at your own risk. 
              The author assumes no responsibility for any issues or damages that may arise from using this script.

"""

import bpy
from mathutils import Vector


def get_objects():
    """
    Get active object and selected objects
    
    Returns:
        Object: Active object
        List[Object]: Selected objects
        
    """
    active_obj = bpy.context.active_object
    selected_objects = bpy.context.selected_objects
    return active_obj, selected_objects


def set_key_drivers(active_obj, selected_objects, cleanup=False):
    """
    Create drivers for shape keys that reference the same named shape key of the active object for the selected objects
    
    Args:
        active_obj (Object): Active object
        selected_objects (List[Object]): Selected objects
        cleanup (bool): If remove existing drivers from the shape key. Default is False
        
    """
    for obj in selected_objects:
        mesh = obj.data
        shape_keys = mesh.shape_keys
        for shape_key in shape_keys.key_blocks.keys():
            print(shape_key)
            if shape_key == "Basis":
                continue
            if cleanup:
                clear_key_driver(targ_obj=obj, shape_key=shape_key)
            set_key_driver(ref_obj=active_obj, targ_obj=obj, shape_key=shape_key)
        

def clear_key_driver(targ_obj, shape_key):
    """
    Remove all drivers from the shape key
    
    Args:
        targ_obj (Object): The object which you want to remove drivers
        shape_key (str): The name of shape key
        
    """
    if targ_obj.data.shape_keys.key_blocks.get(shape_key, None) is None:
        print(f"Shape key {shape_key} is not found")
        return
    targ_obj.data.shape_keys.key_blocks[shape_key].driver_remove("value")
            
            
def set_key_driver(ref_obj, targ_obj, shape_key):
    """
    Create driver for the shape key that reference the same named shape key of the active object for the selected objects
    
    Args:
        ref_obj (Object): The object which have the drivers that you want copy
        targ_obj (Object): The object which you want to set the drivers
        shape_key (str): The name of shape key
        
    """
    if ref_obj == targ_obj:
        return
    d = targ_obj.data.shape_keys.key_blocks[shape_key].driver_add("value")
    d.driver.type = 'AVERAGE'
    
    var = d.driver.variables.new()
    var.name = "value"
    var.type = "SINGLE_PROP"
    
    var.targets[0].id_type = "KEY"
    var.targets[0].id = ref_obj.data.shape_keys
    var.targets[0].data_path = f"key_blocks[\"{shape_key}\"].value"
    
    
if __name__ == "__main__":
    active_obj, selected_objects = get_objects()
    set_key_drivers(active_obj, selected_objects, True)