private static Coordinate Intersection(PlanarPolygon3D poly, LineString line)
{
var seq = line.CoordinateSequence;
if (seq.Count == 0)
{
return(null);
}
// start point of line
var p0 = seq.GetCoordinateCopy(0);
double d0 = poly.Plane.OrientedDistance(p0);
// for each segment in the line
var p1 = p0.Copy();
for (int i = 0; i < seq.Count - 1; i++)
{
seq.GetCoordinate(i, p0);
seq.GetCoordinate(i + 1, p1);
double d1 = poly.Plane.OrientedDistance(p1);
/**
* If the oriented distances of the segment endpoints have the same sign,
* the segment does not cross the plane, and is skipped.
*/
if (d0 * d1 > 0)
{
continue;
}
/**
* Compute segment-plane intersection point
* which is then used for a point-in-polygon test.
* The endpoint distances to the plane d0 and d1
* give the proportional distance of the intersection point
* along the segment.
*/
var intPt = SegmentPoint(p0, p1, d0, d1);
// Coordinate intPt = polyPlane.intersection(p0, p1, s0, s1);
if (poly.Intersects(intPt))
{
return(intPt);
}
// shift to next segment
d0 = d1;
}
return(null);
}
/// <summary>Compute distance between a polygon and the rings of another.</summary>
private void ComputeMinDistancePolygonRings(PlanarPolygon3D poly, Polygon ringPoly,
bool flip)
{
// compute shell ring
ComputeMinDistancePolygonLine(poly, ringPoly.ExteriorRing, flip);
if (_isDone)
{
return;
}
// compute hole rings
int nHole = ringPoly.NumInteriorRings;
for (int i = 0; i < nHole; i++)
{
ComputeMinDistancePolygonLine(poly, ringPoly.GetInteriorRingN(i), flip);
if (_isDone)
{
return;
}
}
}