_getCameraDef() {
    const camera = super._getCameraDef()
    if (this._isImmersive()) {
      camera.facade = extendAsXRCamera(camera.facade)
      camera.xrSession = this.xrSession
      camera.xrReferenceSpace = this.xrReferenceSpace
    }
    return camera
  }
@override to use an XR stereo camera when in immersive XR mode