copy_pivot.py

"""
Copy Pivot - Copies the active object's origin to all other selected objects.

The objects themselves do not move — only their pivot point (origin) is
repositioned to exactly match the active object's origin. Useful when a group
of objects all need the same pivot reference point.
"""

import bpy
from typing import Optional


def copy_pivot(context) -> Optional[str]:
    """Copy the active object's origin to all other selected mesh objects.

    Uses the 3D cursor as an intermediary (saves and restores its state).

    Args:
        context: Current Blender context.

    Returns:
        Error string on failure, None on success.
    """
    template = context.active_object
    if not template:
        return "No active object — the active object's origin is used as the source"

    targets = [o for o in context.selected_objects
               if o != template and o.type == 'MESH']
    if not targets:
        return (
            "No other mesh objects selected — "
            "select the objects that should receive the pivot copy"
        )

    cursor     = context.scene.cursor
    saved_loc  = cursor.location.copy()
    saved_rot  = cursor.rotation_euler.copy()
    active_obj = context.view_layer.objects.active
    sel_states = {o: o.select_get() for o in bpy.data.objects}

    try:
        # Temporarily move cursor to the template's world origin
        cursor.location       = template.matrix_world.translation.copy()
        cursor.rotation_euler = template.rotation_euler.copy()

        bpy.ops.object.select_all(action='DESELECT')

        for obj in targets:
            obj.select_set(True)
            context.view_layer.objects.active = obj
            bpy.ops.object.origin_set(type='ORIGIN_CURSOR')
            obj.select_set(False)

    finally:
        cursor.location       = saved_loc
        cursor.rotation_euler = saved_rot
        for o, was_sel in sel_states.items():
            o.select_set(was_sel)
        if active_obj:
            context.view_layer.objects.active = active_obj

    return None


class OBJECT_OT_copy_pivot(bpy.types.Operator):
    """Copy the active object's origin to all other selected mesh objects"""
    bl_idname   = "object.copy_pivot"
    bl_label    = "Copy Pivot from Active"
    bl_description = (
        "Reposition the origin of every other selected mesh object to exactly "
        "match the active object's pivot point. The objects themselves do not move"
    )
    bl_options = {'REGISTER', 'UNDO'}

    @classmethod
    def poll(cls, context):
        return (
            context.mode == 'OBJECT' and
            context.active_object is not None and
            len(context.selected_objects) >= 2
        )

    def execute(self, context):
        error = copy_pivot(context)
        if error:
            self.report({'WARNING'}, error)
            return {'CANCELLED'}
        return {'FINISHED'}


# ─── Registration ─────────────────────────────────────────────────────────────

classes = (
    OBJECT_OT_copy_pivot,
)


def register():
    for cls in classes:
        bpy.utils.register_class(cls)


def unregister():
    for cls in reversed(classes):
        bpy.utils.unregister_class(cls)