public Point ClosestPointFromPointToPolygon(CustomPolygon customPolygon, Point point)
{
if (customPolygon.GetPolygonVertices().Count == 2) // horizontal line
{
double minX = customPolygon.polygon.Points[0].X;
double maxX = customPolygon.polygon.Points[0].X;
for (int i = 1; i < customPolygon.polygon.Points.Count; i++)
{
Point q = customPolygon.polygon.Points[i];
minX = Math.Min(q.X, minX);
maxX = Math.Max(q.X, maxX);
}
if (point.X < minX)
{
point.X = minX;
}
if (point.X > maxX)
{
point.X = maxX;
}
point.Y = customPolygon.center.Y;
}
else // n > 2
{
// list of lines in polygon
List <Line> polygonLines = customPolygon.GetPolygonLines();
Point? minPoint = null;
double minDist = double.MaxValue;
// for each line in polygon, find the perpendicular line from point
foreach (var line in polygonLines)
{
Point p1 = new Point(line.X1, line.Y1);
Point p2 = new Point(line.X2, line.Y2);
// calculate slopes
double slope = CustomPolygon.GetSlope(p1, p2);
double perpSlope = CustomPolygon.GetPerpendicularSlope(slope);
Debug.WriteLine("slope:{0} perp:{1}", slope, perpSlope);
// perpendicular line from point
Line perpLine = CustomPolygon.GetPerpLine(point, perpSlope);
// find intersection point
Point?intersectionPoint = CustomPolygon.GetIntersectionPoint(line, perpLine);
if (intersectionPoint.HasValue)
{
//get distance from point
double dist = CustomPolygon.GetDistance(intersectionPoint.Value, point);
Debug.WriteLine("dist: {0}", dist);
// does this line intersect the polygon line
// is the intersection point and the point a min distance
if (CustomPolygon.IsPointInLine(intersectionPoint.Value, line) && dist < minDist)
{
minDist = dist;
minPoint = intersectionPoint;
}
}
else
{
throw new Exception("Intersection Point is null even though it should have a coordinate");
}
}
// If there is no minpoint we calculate the closest distance from the point to the polygon corners
if (!minPoint.HasValue)
{
minDist = double.MaxValue;
PointCollection points = customPolygon.polygon.Points;
for (int i = 0; i < points.Count; i++)
{
double dist = CustomPolygon.GetDistance(points[i], point);
if (dist < minDist)
{
minDist = dist;
minPoint = points[i];
}
}
}
point = minPoint.Value;
}
return(point);
}
private List <Double> GetExtendedDistanceList(PointCollection points, Point clickPoint)
{
List <Double> extendedDistances = new List <Double>();
const double offset = 0.01;
for (int i = 0; i < points.Count; i++)
{
Point objectivePoint = points[i];
// get the line from objective point to the clickpoint
Line clickLine = new Line();
clickLine.X1 = objectivePoint.X;
clickLine.X2 = clickPoint.X;
clickLine.Y1 = objectivePoint.Y;
clickLine.Y2 = clickPoint.Y;
Point?intersectionPoint = null;
// we cycle through the polygon points 2 at a time, finding the polygon line
// that intersects with the extended clickLine
for (int j = 0; j < points.Count; j++)
{
Point currentPoint = points[j];
Point nextPoint;
if ((j + 1) < points.Count)
{
nextPoint = points[j + 1];
}
else
{
// if the point is the last point, we cycle back to get the point in the 0th index
nextPoint = points[0];
}
Line polygonLine = new Line();
polygonLine.X1 = currentPoint.X;
polygonLine.X2 = nextPoint.X;
polygonLine.Y1 = currentPoint.Y;
polygonLine.Y2 = nextPoint.Y;
intersectionPoint = CustomPolygon.GetIntersectionPoint(clickLine, polygonLine);
// Make sure the intersection point calculated is not the objectivePoint
if (intersectionPoint.HasValue &&
// this part is trick af because it is floating point calculation. Need some offset
(!CustomPolygon.FloatsAreEqual(objectivePoint.X, intersectionPoint.Value.X, offset) ||
!CustomPolygon.FloatsAreEqual(objectivePoint.Y, intersectionPoint.Value.Y, offset))
&&
CustomPolygon.IsPointInLine(intersectionPoint.Value, polygonLine))
{
// if we have discovered the point we break out of the for loop
Console.WriteLine("the valid intersection point is ({0}, {1})", intersectionPoint.Value.X, intersectionPoint.Value.Y);
break;
}
}
// Get distance between the polygon corner and the intersecting coordinate
if (intersectionPoint.HasValue)
{
double extendedDistance = CustomPolygon.GetDistance(intersectionPoint.Value, objectivePoint);
extendedDistances.Add(extendedDistance);
}
//else
//{
// // I should be getting some kind of intersection here if not
// throw new Exception("Intersection Point is null even though it should have a coordinate");
//}
}
return(extendedDistances);
}
