public float getVRHeightAdjustment() {
        if( viewManager != null ) return viewManager.getHeightAdjustment();
        return 0f;
    }
Get the VR headset height from the ground.
@return the VR headset height from the ground.
@see #setVRHeightAdjustment(float)
jme3-vr/src/main/java/com/jme3/app/VRApplication.java