public List <Coordinate> GenerateBootstrapRoute(Geofence geofence, double circleSize = 70)
{
var geometryFactory = GeometryFactory.Default;
var xMod = Math.Sqrt(0.75);
var yMod = Math.Sqrt(0.568);
var points = new List <Coordinate>();
var polygon = geofence.Feature.Geometry.Coordinates;
var line = geometryFactory.CreateLineString(polygon);
var coords = geofence.BBox.Coordinates;
var minLat = coords.Min(x => x.X);
var minLon = coords.Min(x => x.Y);
var maxLat = coords.Max(x => x.X);
var maxLon = coords.Max(x => x.Y);
var currentLatLng = new NetTopologySuite.Geometries.Coordinate(maxLat, maxLon);
var lastLatLng = new NetTopologySuite.Geometries.Coordinate(minLat, minLon);
var startLatLng = Destination(currentLatLng, 90, circleSize * 1.5);
var endLatLng = Destination(Destination(lastLatLng, 270, circleSize * 1.5), 180, circleSize);
var row = 0;
var heading = 270;
var i = 0;
while (currentLatLng.X > endLatLng.X)
{
do
{
var point = new Point(currentLatLng);
var distance = point.Distance(line);
if (distance <= circleSize || distance == 0 || polygon.Contains(currentLatLng))
{
points.Add(new Coordinate(currentLatLng.X, currentLatLng.Y));
}
currentLatLng = Destination(currentLatLng, heading, xMod * circleSize * 2);
i++;
} while ((heading == 270 && currentLatLng.Y > endLatLng.Y) || (heading == 90 && currentLatLng.Y < startLatLng.Y));
currentLatLng = Destination(currentLatLng, 180, yMod * circleSize * 2);
heading = row % 2 == 1
? 270
: 90;
currentLatLng = Destination(currentLatLng, heading, xMod * circleSize * 3);
row++;
}
return(points);
}
/// <summary>
/// Returns the point that is a distance and heading away from
/// the given origin point.
/// </summary>
/// <param name="latlng">Origin coordinate</param>
/// <param name="heading">Heading in degrees, clockwise from 0 degrees north.</param>
/// <param name="distance">Distance in meters</param>
/// <returns>The destination coordinate</returns>
private static NetTopologySuite.Geometries.Coordinate Destination(NetTopologySuite.Geometries.Coordinate latlng, double heading, double distance)
{
heading = (heading + 360) % 360;
const double rad = Math.PI / 180;
const double radInv = 180 / Math.PI;
const int r = 6378137; // approximation of Earth's radius
var lon1 = latlng.Y * rad;
var lat1 = latlng.X * rad;
var rheading = heading * rad;
var sinLat1 = Math.Sin(lat1);
var cosLat1 = Math.Cos(lat1);
var cosDistR = Math.Cos(distance / r);
var sinDistR = Math.Sin(distance / r);
var lat2 = Math.Asin((sinLat1 * cosDistR) + (cosLat1 *
sinDistR * Math.Cos(rheading)));
var lon2 = lon1 + Math.Atan2(Math.Sin(rheading) * sinDistR *
cosLat1, cosDistR - (sinLat1 * Math.Sin(lat2)));
lon2 *= radInv;
lon2 = lon2 > 180 ? lon2 - 360 : lon2 < -180 ? lon2 + 360 : lon2;
return(new NetTopologySuite.Geometries.Coordinate(lat2 * radInv, lon2));
}
