/// <summary>
/// Gets new collection of coordinated for a circle in a given coordinate space, size and precision.
/// </summary>
/// <param name="centroid">Center point.</param>
/// <param name="radius">Radius in kilometers for the Earth space or in pixels for the Device space.</param>
/// <param name="numberOfPoints">Precision as a number of circle contour points.</param>
/// <returns>A list of <see cref="ISimpleCoordinate"/>.</returns>
static IList <ISimpleCoordinate> GetCircleCoordinates(ISimpleCoordinate centroid, double radius, int numberOfPoints)
{
IList <ISimpleCoordinate> circleCoordinates = new List <ISimpleCoordinate>();
// Draw a circular zone.
double pointAngle = Math.PI / numberOfPoints * 2;
// Radius in degrees along latitude or longitude at Equator;
// 20037 = Half of EarthDistance along the equator in kilometers
radius /= 20037.707072954225 / 180;
for (int i = 0; i < numberOfPoints; i++)
{
float y = (float)(Math.Cos(i * pointAngle) * radius + centroid.Y);
float xOffset = (float)(Math.Sin(i * pointAngle) * radius);
// Mind that we are not at Equator.
xOffset = (float)(xOffset / Math.Abs(Math.Cos(y * Math.PI / 180)));
float x = xOffset + (float)centroid.X;
circleCoordinates.Add(new Coordinate(x, y));
}
return(circleCoordinates);
}
/// <summary> /// Gets the distance squared between 2 points. /// </summary> /// <param name="source">The source.</param> /// <param name="destination">The destination.</param> /// <returns>distance</returns> static double GetDistanceSquared(ISimpleCoordinate source, ISimpleCoordinate destination) => (destination.X - source.X) * (destination.X - source.X) + (destination.Y - source.Y) * (destination.Y - source.Y);
