private void CheckDD(Coordinate p1, Coordinate p2, Coordinate q1,
                             Coordinate q2, Coordinate intPt)
        {
            Coordinate intPtDD = CGAlgorithmsDD.Intersection(p1, p2, q1, q2);
            bool       isIn    = IsInSegmentEnvelopes(intPtDD);

            Debug.WriteLine("DD in env = " + isIn + "  --------------------- " + intPtDD);
            double distance = intPt.Distance(intPtDD);

            if (distance > 0.0001)
            {
                Debug.WriteLine("Distance = " + distance);
            }
        }