public void setVRHeightAdjustment(float amount) {
        if( viewManager != null ) viewManager.setHeightAdjustment(amount);
    }
Set the VR headset height from the ground.
@param amount the VR headset height from the ground.
@see #getVRHeightAdjustment()
jme3-vr/src/main/java/com/jme3/app/VRApplication.java