/// <summary> /// /// </summary> /// <param name="p"></param> /// <param name="p1"></param> /// <param name="p2"></param> public override void ComputeIntersection(ICoordinate p, ICoordinate p1, ICoordinate p2) { isProper = false; // do between check first, since it is faster than the orientation test if (Envelope.Intersects(p1, p2, p)) { if ((CGAlgorithms.OrientationIndex(p1, p2, p) == 0) && (CGAlgorithms.OrientationIndex(p2, p1, p) == 0)) { isProper = true; if (p.Equals(p1) || p.Equals(p2)) { isProper = false; } result = DoIntersect; return; } } result = DontIntersect; }
/// <summary> /// /// </summary> /// <param name="p1"></param> /// <param name="p2"></param> /// <param name="q1"></param> /// <param name="q2"></param> /// <returns></returns> public override int ComputeIntersect(ICoordinate p1, ICoordinate p2, ICoordinate q1, ICoordinate q2) { isProper = false; // first try a fast test to see if the envelopes of the lines intersect if (!Envelope.Intersects(p1, p2, q1, q2)) { return(DontIntersect); } // for each endpoint, compute which side of the other segment it lies // if both endpoints lie on the same side of the other segment, // the segments do not intersect int Pq1 = CGAlgorithms.OrientationIndex(p1, p2, q1); int Pq2 = CGAlgorithms.OrientationIndex(p1, p2, q2); if ((Pq1 > 0 && Pq2 > 0) || (Pq1 < 0 && Pq2 < 0)) { return(DontIntersect); } int Qp1 = CGAlgorithms.OrientationIndex(q1, q2, p1); int Qp2 = CGAlgorithms.OrientationIndex(q1, q2, p2); if ((Qp1 > 0 && Qp2 > 0) || (Qp1 < 0 && Qp2 < 0)) { return(DontIntersect); } bool collinear = (Pq1 == 0 && Pq2 == 0 && Qp1 == 0 && Qp2 == 0); if (collinear) { return(ComputeCollinearIntersection(p1, p2, q1, q2)); } /* * Check if the intersection is an endpoint. If it is, copy the endpoint as * the intersection point. Copying the point rather than computing it * ensures the point has the exact value, which is important for * robustness. It is sufficient to simply check for an endpoint which is on * the other line, since at this point we know that the inputLines must * intersect. */ if (Pq1 == 0 || Pq2 == 0 || Qp1 == 0 || Qp2 == 0) { isProper = false; if (Pq1 == 0) { intPt[0] = new Coordinate(q1); } if (Pq2 == 0) { intPt[0] = new Coordinate(q2); } if (Qp1 == 0) { intPt[0] = new Coordinate(p1); } if (Qp2 == 0) { intPt[0] = new Coordinate(p2); } } else { isProper = true; intPt[0] = Intersection(p1, p2, q1, q2); } return(DoIntersect); }