public static Point ClosestPointFromPointToPolygon(CustomPolygon polygon, Point point)
{
// we keep track of point with minimum distance
Point? minPoint = null;
double minDist = double.MaxValue;
List <CustomLine> polygonLines = polygon.GetPolygonLines();
// for each line in polygon, find the perpendicular line from point
for (int i = 0; i < polygonLines.Count(); i++)
{
CustomLine lineSegment = polygonLines[i];
double slope = lineSegment.getSlope();
double perpSlope = CustomLine.getPerpendicularSlope(slope);
CustomLine perpLine = new CustomLine(point, perpSlope);
Point? intersectionPoint = CustomLine.getIntersectionCoordinates(lineSegment, perpLine);
if (intersectionPoint.HasValue)
{
double dist = Utilities.getDistance(intersectionPoint.Value, point);
// does this line intersect the polygon line segment?
// is the intersection point and the point a min distance
if (CustomLine.withinLineSegment(intersectionPoint.Value, lineSegment) &&
dist < minDist)
{
minDist = dist;
minPoint = intersectionPoint;
}
}
else
{
throw new Exception("Intersection Point is null even though it should have a coordinate");
}
}
// If there is a minpoint we are good to go
if (minPoint.HasValue)
{
return(minPoint.Value);
}
// or else we calculate the closest distance from the point to the polygon corners
else
{
minDist = double.MaxValue;
PointCollection points = polygon.GetPoints();
for (int i = 0; i < points.Count; i++)
{
double dist = Utilities.getDistance(points[i], point);
if (dist < minDist)
{
minDist = dist;
minPoint = points[i];
}
}
}
// If there is a minpoint we are good to go
if (minPoint.HasValue)
{
return(minPoint.Value);
}
else
{
throw new Exception("Point with minimum distance is null even though it should have a coordinate");
}
}
private List <Double> getExtendedDistanceList(PointCollection points, Point clickPoint)
{
List <Double> extendedDistances = new List <Double>();
for (int i = 0; i < points.Count; i++)
{
Point objectivePoint = points[i];
// get the line from objective point to the clickpoint
CustomLine clickLine = new CustomLine(objectivePoint, clickPoint);
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];
}
CustomLine polygonLine = new CustomLine(currentPoint, nextPoint);
intersectionPoint = CustomLine.getIntersectionCoordinates(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
(!Utilities.floatsEqual(objectivePoint.X, intersectionPoint.Value.X, Constants.offset) ||
!Utilities.floatsEqual(objectivePoint.Y, intersectionPoint.Value.Y, Constants.offset))
&&
CustomLine.withinLineSegment(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 = Utilities.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);
}
