@Override
    public void read(JmeImporter im) throws IOException {
        InputCapsule in = im.getCapsule(this);
        spline = (Spline) in.readSavable("spline", null);
    }
interpolate the path giving the time since the beginning and the motionControl
this methods sets the new localTranslation to the spatial of the MotionEvent control.
@param time the time since the animation started
@param control the control over the moving spatial
@param tpf time per frame (in seconds)
@return the distance travelled (in world units)
jme3-core/src/main/java/com/jme3/cinematic/MotionPath.java