private void OnSceneGUI()
        {
            spline          = target as BezierSpline;
            handleTransform = spline.transform;
            handleRotation  = Tools.pivotRotation == PivotRotation.Local ?
                              handleTransform.rotation : Quaternion.identity;

            Vector3 p0 = ShowPoint(0);

            for (int i = 1; i < spline.ControlPointCount; i += 3)
            {
                Vector3 p1 = ShowPoint(i);
                Vector3 p2 = ShowPoint(i + 1);
                Vector3 p3 = ShowPoint(i + 2);

                Handles.color = Color.gray;
                Handles.DrawLine(p0, p1);
                Handles.DrawLine(p2, p3);

                Handles.DrawBezier(p0, p3, p1, p2, Color.white, null, 2f);
                p0 = p3;
            }
            ShowDirections();
        }