/// <summary>
/// Finds the shortest distance between two line segments.
/// </summary>
/// <param name="lineSegment"></param>
/// <param name="otherLineSegment"></param>
/// <param name="shortestDistanceSegment">Outputs a line segment for the shortest found distance.
/// PointA is on the first input line segment, PointB is on the second input line segment. </param>
/// <returns></returns>
public static double ShortestSquaredDistanceToOtherLineSegment(this LineSegment2D lineSegment, LineSegment2D otherLineSegment, out LineSegment2D shortestDistanceSegment)
{
Point2D?intersectionPoint;
if (lineSegment.IntersectsOtherLineSegment(otherLineSegment, out intersectionPoint))
{
shortestDistanceSegment = new LineSegment2D(intersectionPoint.Value, intersectionPoint.Value);
return(0);
}
Point2D pointA, pointB;
double shortestSquaredDistance;
// Check first end point on first segment to second line segment.
pointA = lineSegment.PointA;
shortestSquaredDistance = otherLineSegment.ShortestSquaredDistanceToPoint(lineSegment.PointA, out pointB);
Point2D pointCandidate;
double distanceCandidate;
// Check second end point on first segment to second line segment.
distanceCandidate = otherLineSegment.ShortestSquaredDistanceToPoint(lineSegment.PointB, out pointCandidate);
if (distanceCandidate < shortestSquaredDistance)
{
shortestSquaredDistance = distanceCandidate;
pointA = lineSegment.PointB;
pointB = pointCandidate;
}
// Check first end point on second line segment to first line segment.
distanceCandidate = lineSegment.ShortestSquaredDistanceToPoint(otherLineSegment.PointA, out pointCandidate);
if (distanceCandidate < shortestSquaredDistance)
{
shortestSquaredDistance = distanceCandidate;
pointA = pointCandidate;
pointB = otherLineSegment.PointA;
}
// Check second end point on second line segment to first line segment.
distanceCandidate = lineSegment.ShortestSquaredDistanceToPoint(otherLineSegment.PointB, out pointCandidate);
if (distanceCandidate < shortestSquaredDistance)
{
shortestSquaredDistance = distanceCandidate;
pointA = pointCandidate;
pointB = otherLineSegment.PointB;
}
shortestDistanceSegment = new LineSegment2D(pointA, pointB);
return(shortestSquaredDistance);
}
