How can I check whether a location is within a MapPolygon in the Silverlight Bing Maps control?
I have a MapPolygon which covers a certain area on the Silverlight Bing Maps control, and I would like to know if a particular Location is located within this MapPolygon.
I have tried the following code which doesen't return the result I want because it only checks if the tested location is one of the vertices of t开发者_StackOverflow中文版he MapPolygon, and doesn't check if this Location is contained within this MapPolygon.
polygon.Locations.Contains(new Location(this.Site.Latitude, this.Site.Longitude, this.Site.Altitude));
Is it also possible to determine if two MapPolygons intersect one another?
The polygon.Locations is a list of points defining the polygon.
You have to make a method to find if your point is inside the polygon.
Use something like this (not tested if compiles):
static bool PointInPolygon(LocationCollection polyPoints, Location point)
{
if (polyPoints.Length < 3)
{
return false;
}
bool inside = false;
Location p1, p2;
//iterate each side of the polygon
Location oldPoint = polyPoints[polyPoints.Count - 1];
foreach(Location newPoint in polyPoints)
{
//order points so p1.lat <= p2.lat;
if (newPoint.Latitude > oldPoint.Latitude)
{
p1 = oldPoint;
p2 = newPoint;
}
else
{
p1 = newPoint;
p2 = oldPoint;
}
//test if the line is crossed and if so invert the inside flag.
if ((newPoint.Latitude < point.Latitude) == (point.Latitude <= oldPoint.Latitude)
&& (point.Longitude - p1.Longitude) * (p2.Latitude - p1.Latitude)
< (p2.Longitude - p1.Longitude) * (point.Latitude - p1.Latitude))
{
inside = !inside;
}
oldPoint = newPoint;
}
return inside;
}
And call it like this:
if (PointInPolygon(polygon.Locations, new Location(this.Site.Latitude, this.Site.Longitude, this.Site.Altitude)))
{
//do something
}
Sure both of these things are fairly trivial, take a look at the following article. http://msdn.microsoft.com/en-us/library/cc451895.aspx It gives good methods for Bounding Box, Radius, and Polygon Search. Particularity take note of the pointInPolygon method.
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