// Project a point to polyline.
// point: (p), polyline: (pts)
// output distance relative to the start point of the polyline: (distance)
// output projection point: (outPnt)
// return value:
// true: the point is projected on the polyline without extending the polyline
// false: the point is projected on the polyline through extending the polyline
//
public static bool ProjectPointToPolyline(IMapPoint p,
IPointCollection pts, ref double distance, ref IMapPoint outPnt)
{
distance = 0.0;
double outx = 0.0, outy = 0.0;
IMapPoint p0, p1;
for (int i = 0; i < pts.Count - 1; ++i)
{
p0 = pts[i];
p1 = pts[i + 1];
bool canProject = GeometryAlgorithms.ProjectPointToLine(p.X, p.Y,
p0.X, p0.Y, p1.X, p1.Y, ref outx, ref outy);
if (canProject == true)
{
distance += GeometryAlgorithms.PointDistanceToPoint(outx, outy, p0.X, p0.Y);
outPnt = Runtime.geometryEngine.newMapPoint(outx, outy);
return(true);
}
distance += GeometryAlgorithms.PointDistanceToPoint(p0.X, p0.Y, p1.X, p1.Y);
}
// Project the point by extending the polyline
p0 = pts[0];
p1 = pts[pts.Count - 1];
double d0p = GeometryAlgorithms.PointDistanceToPoint(p.X, p.Y, p0.X, p0.Y);
double d1p = GeometryAlgorithms.PointDistanceToPoint(p.X, p.Y, p1.X, p1.Y);
if (d0p < d1p)
{
// the map point is closer to the beginning of the polyline,
// then extend the beginning segment.
p1 = pts[1];
GeometryAlgorithms.ProjectPointToLine(p.X, p.Y,
p0.X, p0.Y, p1.X, p1.Y, ref outx, ref outy);
distance = GeometryAlgorithms.PointDistanceToPoint(outx, outy, p0.X, p0.Y);
distance *= -1.0;
outPnt = Runtime.geometryEngine.newMapPoint(outx, outy);
}
else
{
// the map point is closer to the endding of the polyline,
// since the loop is ended on the last segment, just use the result is OK.
distance += GeometryAlgorithms.PointDistanceToPoint(outx, outy, p1.X, p1.Y);
outPnt = Runtime.geometryEngine.newMapPoint(outx, outy);
}
return(false);
}
public static double Distance(IMapPoint p1, IMapPoint p2)
{
return(GeometryAlgorithms.PointDistanceToPoint(p1.X, p1.Y, p2.X, p2.Y));
}