// finish calibration
    public void FinishCalibration()
    {
        if (state != State.Calibrating)
        {
            return;
        }

        state = State.Playing;

        // deactivate items
        foreach (GameObject marker in pathMarkers)
        {
            marker.SetActive(false);
        }
        LineRenderer lineRenderer = GetComponent <LineRenderer> ();

        lineRenderer.enabled = false;
        calibrationUI.SetActive(false);
        Destroy(reticle);
        Destroy(calibrator);
        environmentController.GenerateEnvironment();
        robotController.StartRobot();
    }