function Curve3(points) {
            this._length = 0.0;
            this._points = points;
            this._length = this._computeLength(points);
        }
A Curve3 object is a logical object, so not a mesh, to handle curves in the 3D geometric space.
A Curve3 is designed from a series of successive Vector3.
Tuto : http://doc.babylonjs.com/tutorials/How_to_use_Curve3#curve3-object