private void rotateBillboard(Camera cam) {
        switch (alignment) {
            case AxialY:
                rotateAxial(cam, Vector3f.UNIT_Y);
                break;
            case AxialZ:
                rotateAxial(cam, Vector3f.UNIT_Z);
                break;
            case Screen:
                rotateScreenAligned(cam);
                break;
            case Camera:
                rotateCameraAligned(cam);
                break;
        }
    }
rotate the billboard based on the type set

@param cam
           Camera
jme3-core/src/main/java/com/jme3/scene/control/BillboardControl.java