Placing 3D cursor using python

Question

I want to place an object where the cursor is using python. So I need a script that place the 3D cursor where I have the cursor at that moment and then place the already selected object there. To do that I created a quick favorite that call that script loaded as addon (image below)

But I can't get the 3D cursor where the "windows cursor" is pointing. I'd need a script that emulate what the shift+RMB does

I'm just a newbie, please have mercy :) since my code may be neither elegant nor good

bl_info = {
    "name": "Place object",
    "blender": (4, 0 ,2),
    "category": "Object",
}


import bpy
import mathutils


class OBJECT_OT_placeObject(bpy.types.Operator):
    """Place object where the cursor is"""
    bl_idname = "object.place"
    bl_label = "Place Object"
    bl_options = {"REGISTER", "UNDO"}

    def execute(self, context): 
       
        # Mouse cursor coordinates
        mouse_x = bpy.context.region.width // 2
        mouse_y = bpy.context.region.height // 2

        # Get the depsgraph actual
        depsgraph = bpy.context.evaluated_depsgraph_get()

        # Convert mouse coordinates to a ray in 3D space
        ray = bpy.context.scene.ray_cast(depsgraph, origin=bpy.context.area.spaces[0].region_3d.view_location, direction=mathutils.Vector((mouse_x, mouse_y, 0.0)))

        # test if ray intersetcs
        if ray[0]:
            # Mover  3D where the mouse cursor is pointing
            bpy.context.scene.cursor.location = ray[1]
        else:
            print("No se encontró intersección")


        # -----------------------------------------------------------
        # Place object where the cursor is


        # Get the 3D cursor position
        cursor_location = bpy.context.scene.cursor.location

        # Get the selected object
        selected_object = bpy.context.selected_objects[0]

        # Move selected object where the 3D cursor is
        selected_object.location = cursor_location


def menu_func(self, context):
    self.layout.operator(OBJECT_OT_placeObject.bl_idname)

def register():
    bpy.utils.register_class(OBJECT_OT_placeObject)
    bpy.types.VIEW3D_MT_object.append(menu_func)

def unregister():
    bpy.utils.unregister_class(OBJECT_OT_placeObject)

if __name__ == "__main__":
    register()
```

Answer 1

If you have a look at the user preferences, you can see the operator that is triggered by Shift + RMB :

That's bpy.ops.view3d.cursor3d() you can find it in the docs, which apparently is really not that useful in this case if you ask me. It's tricky to use from an operator and I have no idea how one is supposed to know that it needs to be run with 'INVOKE_DEFAULT', but it does. So it should be bpy.ops.view3d.cursor3d('INVOKE_DEFAULT') and it can set 3d cursor location to the mouse position from another operator.

So that would be:

import bpy


class OBJECT_OT_placeObject(bpy.types.Operator):
    """Place object where the cursor is"""
    bl_idname = "object.place"
    bl_label = "Place Object"

    @classmethod
    def poll(cls, context):
        return context.object is not None

    def execute(self, context):
        previous_cursor_location = context.scene.cursor.location.copy()
        bpy.ops.view3d.cursor3d('INVOKE_DEFAULT') 
        context.object.location = context.scene.cursor.location
        context.scene.cursor.location = previous_cursor_location
        return {'FINISHED'}


def register():
    bpy.utils.register_class(OBJECT_OT_placeObject)

def unregister():
    bpy.utils.unregister_class(OBJECT_OT_placeObject)


if __name__ == "__main__":
    register()

Answer 2

You should use a modal operator

import bpy
from bpy.types import Operator
from bpy_extras.view3d_utils import region_2d_to_location_3d
from mathutils import Vector


class OBJECT_OT_place_object(Operator):
    """Place object to the 3D cursor"""

    bl_idname = "object.place"
    bl_label = "Place Object"
    bl_options = {"REGISTER", "UNDO"}

    def invoke(self, context, event):
        self.cursor_location = context.scene.cursor.location.copy()
        context.window_manager.modal_handler_add(self)
        return {"RUNNING_MODAL"}

    def modal(self, context, event):
        cursor_location = region_2d_to_location_3d(
            context.region,
            context.space_data.region_3d,
            (event.mouse_region_x, event.mouse_region_y),
            Vector((0, 0, 0)),
        )
        context.scene.cursor.location = cursor_location

        if event.type in {"RIGHTMOUSE", "ESC"}:
            context.scene.cursor.location = self.cursor_location
            return {"CANCELLED"}

        elif event.type == "LEFTMOUSE":
            for obj in context.selected_objects:
                obj.location = cursor_location
            return {"FINISHED"}

        return {"PASS_THROUGH"}


def menu_func(self, context):
    self.layout.operator(OBJECT_OT_place_object.bl_idname)


def register():
    bpy.utils.register_class(OBJECT_OT_place_object)
    bpy.types.VIEW3D_MT_object.append(menu_func)


def unregister():
    bpy.utils.unregister_class(OBJECT_OT_place_object)
    bpy.types.VIEW3D_MT_object.remove(menu_func)


if __name__ == "__main__":
    register()