private void AddResultVertices(Geometry geom0, Geometry geom1)
{
/*
* Compute rays originating at vertices inside the resultant
* (i.e. A vertices inside B, and B vertices inside A)
*/
var locator = new IndexedPointInAreaLocator(geom1);
var seq = GetVertices(geom0);
bool isCW = !Orientation.IsCCW(seq);
for (int i = 0; i < seq.Count - 1; i++)
{
var vPrev = i == 0 ? seq.GetCoordinate(seq.Count - 2) : seq.GetCoordinate(i - 1);
var v = seq.GetCoordinate(i);
var vNext = seq.GetCoordinate(i + 1);
if (Location.Interior == locator.Locate(v))
{
_area += EdgeRay.AreaTerm(v, vPrev, !isCW);
_area += EdgeRay.AreaTerm(v, vNext, isCW);
}
}
}
private void AddIntersections()
{
var seqA = GetVertices(_geomA);
var seqB = GetVertices(_geomB);
// NTS-specific: these arrays were only written to, never read from.
////bool[] isIntersected0 = new bool[seqA.Count - 1];
////bool[] isIntersected1 = new bool[seqB.Count - 1];
bool isCCWA = Orientation.IsCCW(seqA);
bool isCCWB = Orientation.IsCCW(seqB);
// Compute rays for all intersections
var li = new RobustLineIntersector();
for (int i = 0; i < seqA.Count - 1; i++)
{
var a0 = seqA.GetCoordinate(i);
var a1 = seqA.GetCoordinate(i + 1);
if (isCCWA)
{
// flip segment orientation
(a0, a1) = (a1, a0);
}
for (int j = 0; j < seqB.Count - 1; j++)
{
var b0 = seqB.GetCoordinate(j);
var b1 = seqB.GetCoordinate(j + 1);
if (isCCWB)
{
// flip segment orientation
(b0, b1) = (b1, b0);
}
li.ComputeIntersection(a0, a1, b0, b1);
if (li.HasIntersection)
{
// NTS-specific: these arrays were only written to, never read from.
////isIntersected0[i] = true;
////isIntersected1[j] = true;
/*
* With both rings oriented CW (effectively)
* There are two situations for segment intersections:
*
* 1) A entering B, B exiting A => rays are IP-A1:R, IP-B0:L
* 2) A exiting B, B entering A => rays are IP-A0:L, IP-B1:R
* (where :L/R indicates result is to the Left or Right).
*
* Use full edge to compute direction, for accuracy.
*/
var intPt = li.GetIntersection(0);
bool isAenteringB = OrientationIndex.CounterClockwise == Orientation.Index(a0, a1, b1);
if (isAenteringB)
{
_area += EdgeRay.AreaTerm(intPt, a0, a1, true);
_area += EdgeRay.AreaTerm(intPt, b1, b0, false);
}
else
{
_area += EdgeRay.AreaTerm(intPt, a1, a0, false);
_area += EdgeRay.AreaTerm(intPt, b0, b1, true);
}
}
}
}
}
