public bool Intersects(BoundingCircle bc) { return Intersects(bc.Center, bc.Radius); }
/// <summary>
/// Returns true or false depending on whether the segment intersects the bounding circle
/// </summary>
/// <param name="segment"></param>
/// <param name="boundingCircle"></param>
/// <returns></returns>
public static bool Intersects(this GeoSegment segment, BoundingCircle boundingCircle)
{
// check if either of the end points of the seg are inside the
// circle
var d1 = segment[0].DistanceRadians(boundingCircle.Center);
if (d1 < boundingCircle.Radius)
return true;
var d2 = segment[1].DistanceRadians(boundingCircle.Center);
if (d2 < boundingCircle.Radius)
return true;
if (boundingCircle.Center.DistanceToGreatCircle(segment) > boundingCircle.Radius)
return false;
// calculate point of intersection of great circle containing
// (lat, lon) and perpendicular to great circle containing
// (lat1, lon1) and (lat2, lon2)
var g = segment[0].Cross(segment[1]);
var f = boundingCircle.Center.Cross(g);
// Reusing g object for i
var i = f.Cross(g).Normalized;
// check if point of intersection lies on the segment
// length of seg
var d = segment.LengthRadians;
// Make sure the intersection point is inside the exclusion
// zone
if (boundingCircle.Center.DistanceRadians(i) < boundingCircle.Radius)
{
// between seg endpoints and first point of intersection
var d11 = segment[0].DistanceRadians(i);
var d12 = segment[1].DistanceRadians(i);
// Check the distance of the intersection point and either
// endpoint to see if it falls between them. Add a second
// test to make sure that we are on the shorter of the two
// segments between the endpoints.
return (d11 <= d && d12 <= d && Math.Abs(d11 + d12 - d) < 0.01f);
}
// Make sure the intersection point is inside the exclusion
// zone, reusing i object for i2
var i2 = i.Antipode;
if (boundingCircle.Center.DistanceRadians(i2) < boundingCircle.Radius)
{
// between seg1 endpoints and second point of intersection
var d21 = segment[0].DistanceRadians(i2);
var d22 = segment[1].DistanceRadians(i2);
// Check the distance of the intersection point and either
// endpoint to see if it falls between them. Add a second
// test to make sure that we are on the shorter of the two
// segments between the endpoints.
return (d21 <= d && d22 <= d && Math.Abs(d21 + d22 - d) < 0.01f);
}
return false;
}
/**
* this can be used to set up the "rest" of the Limit if created from
* serialization. just make it public
*/
void Initialize()
{
foreach (var geo in Geos)
{
// this reason we extract a rectangular extents is
// for placing random points within the area.
if (geo.Latitude < _minLat) _minLat = geo.Latitude;
if (geo.Latitude > _maxLat) _maxLat = geo.Latitude;
if (geo.Longitude < _minLon) _minLon = geo.Longitude;
if (geo.Longitude > _maxLon) _maxLon = geo.Longitude;
}
// need this for a few things
// create a region for testing inside / outside
_region = new GeoArray(Geos);
// BoundingCircle attempt to get the center of the polygon. when the
// shape is not a poly, it hacks a fur ball
_boundingCircle = Geos.Count < 3 ? new BoundingCircle(new Geo(0.0, 0.0), 0.0) : new BoundingCircle(_region);
_centerOfRegion = _boundingCircle.Center;
SetIsClockWise();
}
/// <summary>
/// Does the segment come near the region defined by boundingCircle?
/// </summary>
/// <param name="segment"></param>
/// <param name="boundingCircle"></param>
/// <param name="near">Radius of approach, in radians</param>
/// <returns></returns>
public static bool IsNear(this GeoSegment segment, BoundingCircle boundingCircle, double near)
{
return segment.IsInside(near + boundingCircle.Radius, boundingCircle.Center);
}