This class needs to be implemented to make an AR or VR platform available to Godot and these should be implemented as C++ modules or GDNative modules (note that for GDNative the subclass ARVRScriptInterface should be used). Part of the interface is exposed to GDScript so you can detect, enable and configure an AR or VR platform.
Interfaces should be written in such a way that simply enabling them will give us a working setup. You can query the available interfaces through ARVRServer.
If this is an AR interface that requires displaying a camera feed as the background, this method returns the feed id in the [CameraServer] for this interface.
If supported, returns the status of our tracking. This will allow you to provide feedback to the user whether there are issues with positional tracking.
Call this to initialize this interface. The first interface that is initialized is identified as the primary interface and it will be used for rendering output.
If you do this for a platform that handles its own output (such as OpenVR) Godot will show just one eye without distortion on screen. Alternatively you can add a separate viewport node to your scene and enable AR/VR on that viewport and it will be used to output to the HMD leaving you free to do anything you like in the main window such as using a separate camera as a spectator camera or render out something completely different.
While currently not used you can activate additional interfaces, you may wish to do this if you want to track controllers from other platforms. However at this point in time only one interface can render to an HMD.
This interface outputs to an external device, if the main viewport is used the on screen output is an unmodified buffer of either the left or right eye (stretched if the viewport size is not changed to the same aspect ratio of get_render_targetsize. Using a separate viewport node frees up the main viewport for other purposes.
Mono output, this is mostly used internally when retrieving positioning information for our camera node or when stereo scopic rendering is not supported.