/// <summary>
/// Adapted from http://msdn.microsoft.com/en-us/library/cc451895.aspx
/// </summary>
/// <param name="geo"></param>
/// <param name="region"></param>
/// <returns></returns>
public static bool IsInside(this Geo geo, GeoArray region)
{
if (region == null) throw new ArgumentNullException("region");
if (!region.IsClosed) throw new ArgumentException("Region must be closed", "region");
var points = region.ToArray();
var j = points.Length - 1;
var inPoly = false;
for (var i = 0; i < points.Length; i++)
{
if (points[i].Longitude < geo.Longitude && points[j].Longitude >= geo.Longitude ||
points[j].Longitude < geo.Longitude && points[i].Longitude >= geo.Longitude)
if (points[i].Latitude + (geo.Longitude - points[i].Longitude) / (points[j].Longitude - points[i].Longitude) *
(points[j].Latitude - points[i].Latitude) < geo.Latitude)
inPoly = !inPoly;
j = i;
}
return inPoly;
}
public static bool IsInsideOld(this Geo geo, GeoArray region)
{
if (region == null) throw new ArgumentNullException("region");
if (!region.BoundingBox.Contains(geo)) return false;
if (!region.IsClosed) throw new ArgumentException("Region must be closed", "region");
var c = region.Center;
// bail out if the point is more than 90 degrees off the centroid
if (geo.DistanceRadians(c) >= MoreMath.PiOverTwo) throw new ArgumentException("Point cannot be more than 90 degrees from center of region to test", "geo");
var n = region.Length - 1;
var v = region.ToArray();
var wn = 0; // the winding number counter
// loop through all edges of the polygon
for (var i = 0; i < n; i++)
{ // edge from V[i] to V[i+1]
if (v[i].Latitude <= geo.Latitude)
{
// start y <= P.y
if ((v[i + 1].Latitude > geo.Latitude) && // an upward crossing and
(IsLeft(v[i], v[i + 1], geo) > 0)) // P left of edge
++wn; // have a valid up intersect
}
else
{
// start y > P.y (no test needed)
if ((v[i + 1].Latitude <= geo.Latitude) && // a downward crossing
(IsLeft(v[i], v[i + 1], geo) < 0)) // P right of edge
--wn; // have a valid down intersect
}
}
return wn != 0;
}