set_pivot_to_cursor.py

"""
Set Pivot to Cursor - Sets object pivot points to the 3D cursor.

This module handles setting the origin (pivot point) of selected objects
to match the 3D cursor's position and orientation, with an option to
invert the Z axis by rotating the origin 180° on the local X axis.
"""

import bpy
import math
from typing import Optional


def set_pivot_to_cursor(context) -> Optional[str]:
    """Set pivot point to 3D cursor for all selected objects.

    Moves the origin of each selected object to the 3D cursor position,
    aligning the origin rotation to match the cursor orientation.

    Args:
        context: Current Blender context

    Returns:
        Error message if operation fails, None otherwise
    """
    if not context.selected_objects:
        return "No objects selected"

    # Save current transform settings
    original_orientation = context.scene.transform_orientation_slots[0].type
    original_use_origin = context.tool_settings.use_transform_data_origin

    try:
        # Enable "Affect Only Origins" transform mode
        context.tool_settings.use_transform_data_origin = True

        # Set transform orientation to CURSOR so origin aligns to cursor rotation
        context.scene.transform_orientation_slots[0].type = 'CURSOR'

        # Move all selected origins to the cursor position
        bpy.ops.object.origin_set(type='ORIGIN_CURSOR')

        # Align origin orientation to match cursor rotation
        bpy.ops.transform.transform(mode='ALIGN')

    finally:
        # Restore transform settings regardless of success or failure
        context.scene.transform_orientation_slots[0].type = original_orientation
        context.tool_settings.use_transform_data_origin = original_use_origin

    return None


def invert_pivot_z_axis(context) -> Optional[str]:
    """Rotate the origin 180° on X to invert the Z axis direction.

    Args:
        context: Current Blender context

    Returns:
        Error message if operation fails, None otherwise
    """
    if not context.selected_objects:
        return "No objects selected"

    # Save current transform settings
    original_orientation = context.scene.transform_orientation_slots[0].type
    original_use_origin = context.tool_settings.use_transform_data_origin

    try:
        # Enable "Affect Only Origins" transform mode
        context.tool_settings.use_transform_data_origin = True

        # Use LOCAL orientation so rotation is relative to each object's own axes
        context.scene.transform_orientation_slots[0].type = 'LOCAL'

        # Rotate 180° on X axis — this flips the Z axis direction
        bpy.ops.transform.rotate(
            value=math.pi,
            orient_axis='X',
            constraint_axis=(True, False, False)
        )

    finally:
        # Restore transform settings regardless of success or failure
        context.scene.transform_orientation_slots[0].type = original_orientation
        context.tool_settings.use_transform_data_origin = original_use_origin

    return None


class OBJECT_OT_set_pivot_to_cursor(bpy.types.Operator):
    """Set pivot point to 3D cursor position and orientation"""
    bl_idname = "object.set_pivot_to_cursor"
    bl_label = "Set Pivot to Cursor"
    bl_description = (
        "Move the origin of selected objects to the 3D cursor, "
        "matching its position and orientation"
    )
    bl_options = {'REGISTER', 'UNDO'}

    @classmethod
    def poll(cls, context):
        return context.mode == 'OBJECT' and len(context.selected_objects) > 0

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


class OBJECT_OT_invert_pivot_z_axis(bpy.types.Operator):
    """Invert the Z axis of the pivot point by rotating 180° on local X"""
    bl_idname = "object.invert_pivot_z_axis"
    bl_label = "Invert Pivot Z Axis"
    bl_description = (
        "Rotate the origin 180° on the local X axis, "
        "effectively flipping the Z axis direction"
    )
    bl_options = {'REGISTER', 'UNDO'}

    @classmethod
    def poll(cls, context):
        return context.mode == 'OBJECT' and len(context.selected_objects) > 0

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


classes = (
    OBJECT_OT_set_pivot_to_cursor,
    OBJECT_OT_invert_pivot_z_axis,
)


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


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