/// <summary>
/// This method will create a circle around the centre point founf within
/// this instantiated object. The method will make use of Earth's Radius at
/// the centre of the circle, as this is a good enough approximation for
/// small circle.
/// </summary>
/// <param name="n">The number of points to be generated</param>
/// <param name="offset">the offset of radius value</param>
/// <returns>A list of coordiantes</returns>
public List <Coordinate> CreateRadialCircle(int n = 360, double offset = 0)
{
// Mean Radius of Earth in meters
double offsetRadians = offset * (Math.PI / 180);
// Get the longitude and latitudes as radians for further calculations
double longitude = Centre.LongitudeAsRadians();
double latitude = Centre.LatitudeAsRadians();
// compute longitude degrees (in radians) at the latitude
double r = (Radius / (Distance.EarthRadius(Centre.Latitude) * Math.Cos(latitude)));
// Create a new centre Spherical point
SphericalCoordinate centre = new SphericalCoordinate(longitude, latitude);
// Create one outer point to use for rotating N times
SphericalCoordinate point = new SphericalCoordinate(longitude + r, latitude);
// Create a new coordinates list for all the radial points
List <Coordinate> coordinates = new List <Coordinate>();
// Rotate around the centre n number of times
for (int i = 0; i < n; i++)
{
// Generate new Coordinate
double phi = offsetRadians + (2.0 * Math.PI / n) * i;
Coordinate c = rotatePoint(point, phi);
coordinates.Add(c);
}
// To create a complete circle
coordinates.Add(coordinates[0]);
return(coordinates);
}
/// <summary>
/// This method will rotate a given point around the given centre centroid
/// within this object by phi radians.
/// </summary>
/// <param name="point">The point to be rotated</param>
/// <param name="phi">The number of radians to move the point by</param>
/// <returns>A coordinate</returns>
private Coordinate rotatePoint(SphericalCoordinate point, double phi)
{
// Map values to new variables for reasons of maintaining sanity
double u = Spherical.X;
double v = Spherical.Y;
double w = Spherical.Z;
double x = point.X;
double y = point.Y;
double z = point.Z;
double a = u * x + v * y + w * z;
double d = Math.Cos(phi);
double e = Math.Sin(phi);
// Create a new Spherical Coordinate
double newX = (a * u + (x - a * u) * d + (v * z - w * y) * e);
double newY = (a * v + (y - a * v) * d + (w * x - u * z) * e);
double newZ = (a * w + (z - a * w) * d + (u * y - v * x) * e);
return(new SphericalCoordinate(newX, newY, newZ).ToCoordinate());
}
public void TestToSphericalCoordinate()
{
// Obtain the Longitude and Latitude as Radians
double lon = centroid.LongitudeAsRadians();
double lat = centroid.LatitudeAsRadians();
// Create an expected SphericalCoordinate object
SphericalCoordinate expected = new SphericalCoordinate(lon, lat);
// Obtain the actual SphericalCoordinate
SphericalCoordinate result = centroid.ToSphericalCoordinate();
// Ensure the X values are the same
Assert.AreEqual(expected.X, result.X);
// Ensure the Y values are the same
Assert.AreEqual(expected.Y, result.Y);
// Ensure the Z values are the same
Assert.AreEqual(expected.Z, result.Z);
}
/// <summary>
/// Primary Constructor
/// </summary>
/// <param name="centre">the centroid of the radius</param>
/// <param name="radius">the radius of the circle in meters</param>
public RadialCircle(Centroid centre, double radius)
{
Centre = centre;
Radius = radius;
Spherical = centre.ToSphericalCoordinate();
}
public void Initalise()
{
coordinate = new SphericalCoordinate(LONGITUDE, LATITUDE);
}
/// <summary>
/// This method will create a circle around the centre point founf within
/// this instantiated object. The method will make use of Earth's Radius at
/// the centre of the circle, as this is a good enough approximation for
/// small circle.
/// </summary>
/// <param name="n">The number of points to be generated</param>
/// <param name="offset">the offset of radius value</param>
/// <returns>A list of coordiantes</returns>
public List<Coordinate> CreateRadialCircle(int n = 360, double offset = 0)
{
// Mean Radius of Earth in meters
double offsetRadians = offset * (Math.PI / 180);
// Get the longitude and latitudes as radians for further calculations
double longitude = Centre.LongitudeAsRadians();
double latitude = Centre.LatitudeAsRadians();
// compute longitude degrees (in radians) at the latitude
double r = (Radius / (Distance.EarthRadius(Centre.Latitude) * Math.Cos(latitude)));
// Create a new centre Spherical point
SphericalCoordinate centre = new SphericalCoordinate(longitude, latitude);
// Create one outer point to use for rotating N times
SphericalCoordinate point = new SphericalCoordinate(longitude + r, latitude);
// Create a new coordinates list for all the radial points
List<Coordinate> coordinates = new List<Coordinate>();
// Rotate around the centre n number of times
for (int i = 0; i < n; i++)
{
// Generate new Coordinate
double phi = offsetRadians + (2.0 * Math.PI / n) * i;
Coordinate c = rotatePoint(point, phi);
coordinates.Add(c);
}
// To create a complete circle
coordinates.Add(coordinates[0]);
return coordinates;
}
/// <summary>
/// This method will rotate a given point around the given centre centroid
/// within this object by phi radians.
/// </summary>
/// <param name="point">The point to be rotated</param>
/// <param name="phi">The number of radians to move the point by</param>
/// <returns>A coordinate</returns>
private Coordinate rotatePoint(SphericalCoordinate point, double phi)
{
// Map values to new variables for reasons of maintaining sanity
double u = Spherical.X;
double v = Spherical.Y;
double w = Spherical.Z;
double x = point.X;
double y = point.Y;
double z = point.Z;
double a = u * x + v * y + w * z;
double d = Math.Cos(phi);
double e = Math.Sin(phi);
// Create a new Spherical Coordinate
double newX = (a * u + (x - a * u) * d + (v * z - w * y) * e);
double newY = (a * v + (y - a * v) * d + (w * x - u * z) * e);
double newZ = (a * w + (z - a * w) * d + (u * y - v * x) * e);
return new SphericalCoordinate(newX, newY, newZ).ToCoordinate();
}
