XRProjectionLayer: textureArrayLength property

The read-only textureArrayLength property of the XRProjectionLayer interface indicates layer's layer count for array textures when using texture-array as the textureType.

The projection layer's layer count for array textures is determined by the user agent or the device. It is reported in the XRSubImage, which can only be accessed inside the frame loop. If you want to manage your own depth buffers and don't want to wait for first frame after layer creation to determine the required dimensions for those buffers, the textureArrayLength property allows access to layer count for array textures outside the frame loop. Allocation of these buffers can happen directly after layer creation.