private Geometry createLinearPath() {

        Material mat = new Material(assetManager, "Common/MatDefs/Misc/Unshaded.j3md");
        mat.getAdditionalRenderState().setWireframe(true);
        mat.setColor("Color", ColorRGBA.Blue);
        Geometry lineGeometry = new Geometry("line", new Curve(spline, 0));
        lineGeometry.setMaterial(mat);
        return lineGeometry;
    }
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