Godot Main::start函数

1. If have assign a script by “-s”, the script is the game loop. Create script_loop as MainLoop

2. Cast mainloop to sceneTree, sml. (The following is the sceneTree in editor)
   

Node include the model in the visual world such as camera,

4. Add autoLoad node to root (Set on Project > Project Settings in editor)
5. Set display mode
6. Set local_game_path
7. Set network, icon…

OS::get_singleton()->set_main_loop(main_loop);