Expose Viewport.get_listener_2d() to the scripting API

[mashumafi]

Godot version

3.4

System information

All

Issue description

get_viewport().get_listener_2d() does not exist. It would be useful to expose this since current camera is exposed already. I am trying to do some logic that would be a lot easier to do knowing the current Listener2D position. I guess another way could be to expose the global position of a listener in case the there is no Listener2D currently and the center of the screen would be used instead.

Steps to reproduce

get_viewport().get_listener_2d() is an error

Minimal reproduction project

Above is enough to reproduce

[akien-mga]

CC @KoBeWi. The 3D get_listener() doesn't seem to be exposed either, but both are implemented in C++.

[KoBeWi]

Listener2D is a node you need to create yourself, so you can as well keep track of it. It might be tricky with multiple listeners, but you could use groups for this purpose.

That said, since we have methods to get current camera, methods to get current listener wouldn't hurt probably.