Silverlight中在BingMap上画一个圆

不解释，直接上代码：

private double rad(double d)

{

	return d * Math.PI / 180;

}

//radius : km

private void DrawCircle(Location center, double radius)

{

	double EARTH_RADIUS = 6371;



	double lon = rad(center.Longitude);

	double lat = rad(center.Latitude);



	double d = radius / EARTH_RADIUS;

	polygon = new MapPolygon()

	{

		Fill = new SolidColorBrush(Colors.Red),

		Opacity = 0.6,

	};

	polygon.Locations = new LocationCollection();



	for (int i = 0; i < 360; i++)

	{

		Location location = new Location();

		double bearing = rad(i);

		location.Latitude = Math.Asin(Math.Sin(lat) * Math.Cos(d) + Math.Cos(lat) * Math.Sin(d) * Math.Cos(bearing));

		location.Longitude = ((lon + Math.Atan2(Math.Sin(bearing) * Math.Sin(d) * Math.Cos(lat), Math.Cos(d) - Math.Sin(lat) * Math.Sin(location.Latitude))) * 180) / Math.PI;

		location.Latitude = location.Latitude * 180 / Math.PI;

		polygon.Locations.Add(location);

	}

	MyMap.Children.Insert(0, polygon);

}