/// <summary>
/// Computes the closest points on a line segment.
/// </summary>
/// <param name="line"></param>
/// <returns>
/// A pair of Coordinates which are the closest points on the line segments.
/// </returns>
public virtual Coordinate[] ClosestPoints(ILineSegmentBase line)
{
LineSegment myLine = new LineSegment(line);
// test for intersection
Coordinate intPt = Intersection(line);
if (intPt != null)
return new[] { intPt, intPt };
/*
* if no intersection closest pair contains at least one endpoint.
* Test each endpoint in turn.
*/
Coordinate[] closestPt = new Coordinate[2];
Coordinate close00 = new Coordinate(ClosestPoint(line.P0));
double minDistance = close00.Distance(line.P0);
closestPt[0] = close00;
closestPt[1] = new Coordinate(line.P0);
Coordinate close01 = new Coordinate(ClosestPoint(line.P1));
double dist = close01.Distance(line.P1);
if (dist < minDistance)
{
minDistance = dist;
closestPt[0] = close01;
closestPt[1] = new Coordinate(line.P1);
}
Coordinate close10 = new Coordinate(myLine.ClosestPoint(P0));
dist = close10.Distance(P0);
if (dist < minDistance)
{
minDistance = dist;
closestPt[0] = new Coordinate(P0);
closestPt[1] = close10;
}
Coordinate close11 = new Coordinate(myLine.ClosestPoint(P1));
dist = close11.Distance(P1);
if (dist < minDistance)
{
closestPt[0] = new Coordinate(P1);
closestPt[1] = close11;
}
return closestPt;
}
/// <summary>
/// Given the specified test point, this checks each segment, and will
/// return the closest point on the specified segment.
/// </summary>
/// <param name="testPoint">The point to test.</param>
/// <returns></returns>
public override Coordinate ClosestPoint(Coordinate testPoint)
{
Coordinate closest = Coordinate;
double dist = double.MaxValue;
for (int i = 0; i < _points.Count - 1; i++)
{
LineSegment s = new LineSegment(_points[i], _points[i + 1]);
Coordinate temp = s.ClosestPoint(testPoint);
double tempDist = testPoint.Distance(temp);
if (tempDist < dist)
{
dist = tempDist;
closest = temp;
}
}
return closest;
}
