ode(floorNode);
        mat4.identity(floorNode.matrix);
        mat4.translate(floorNode.matrix, floorNode.matrix, floorPosition);
      }

      function onRequestSession() {
        return navigator.xr.requestSession('immersive-vr', {
            requiredFeatures: ['local-floor']
        }).then((session) => {
          xrButton.setSession(session);
          session.isImmersive = true;
          onSessionStarted(session);
        });
      }

      function onSessionStarted(session) {
        session.ad