Selection.transforms

Возвращает выборку верхнего уровня, исключая Префабы.

Это наиболее распространенный тип выбора при работе с объектами Scene.

using UnityEngine;
using UnityEditor;

class LookAtMainCamera : ScriptableObject
{
    [MenuItem("Example/Selection looks at Main Camera _l")]

    static void Look()
    {
        var camera = Camera.main;

        if (camera)
        {
            foreach (Transform transform in Selection.transforms)
            {
                Undo.RegisterUndo(transform, transform.name + " Looks at Main Camera");
                transform.LookAt(camera.transform);
            }
        }
    }

    //The menu item will be disabled if nothing is selected.
    [MenuItem("Example/Selection looks at Main Camera _l", true)]
    static bool ValidateSelection()
    {
        return Selection.transforms.Length != 0;
    }
}