/// <summary>
/// Computes the intersion of point p and line p1-p2.
/// </summary>
/// <param name="p">Coordinate of point p.</param>
/// <param name="p1">Coordinate of line p1-p2.</param>
/// <param name="p2">Coordinate of line p1-p2.</param>
public override void ComputeIntersection(Coordinate p, Coordinate p1, Coordinate p2)
{
_isProper = false;
if ((RobustCGAlgorithms.OrientationIndex(p1, p2, p) == 0) &&
(RobustCGAlgorithms.OrientationIndex(p2, p1, p) == 0))
{
if (Between(p1, p2, p))
{
_isProper = true;
if (p.Equals(p1) || p.Equals(p2))
{
_isProper = false;
}
_result = DO_INTERSECT;
return;
}
else
{
_result = DONT_INTERSECT;
return;
}
}
else
{
_result = DONT_INTERSECT;
}
} // public override void ComputeIntersection(Coordinate p, Coordinate p1, Coordinate p2)
} // public override void ComputeIntersection(Coordinate p, Coordinate p1, Coordinate p2)
/// <summary>
/// Computes the intersection of line p1-p2 and line q1-q2.
/// </summary>
/// <param name="p1"></param>
/// <param name="p2"></param>
/// <param name="q1"></param>
/// <param name="q2"></param>
/// <returns></returns>
protected override int ComputeIntersect(Coordinate p1, Coordinate p2, Coordinate q1, Coordinate q2)
{
_isProper = false;
// for each endpoint, compute which side of the other segment it lies
int Pq1 = RobustCGAlgorithms.OrientationIndex(p1, p2, q1);
int Pq2 = RobustCGAlgorithms.OrientationIndex(p1, p2, q2);
int Qp1 = RobustCGAlgorithms.OrientationIndex(q1, q2, p1);
int Qp2 = RobustCGAlgorithms.OrientationIndex(q1, q2, p2);
// if both endpoints lie on the same side of the other segment, the segments do not intersect
if (Pq1 > 0 && Pq2 > 0)
{
return(DONT_INTERSECT);
}
if (Qp1 > 0 && Qp2 > 0)
{
return(DONT_INTERSECT);
}
if (Pq1 < 0 && Pq2 < 0)
{
return(DONT_INTERSECT);
}
if (Qp1 < 0 && Qp2 < 0)
{
return(DONT_INTERSECT);
}
bool isCollinear = ((Pq1 == 0) && (Pq2 == 0) && (Qp1 == 0) && (Qp2 == 0));
if (isCollinear)
{
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(DO_INTERSECT);
} // protected override int ComputeIntersect(Coordinate p1, Coordinate p2, Coordinate q1, Coordinate q2)
