/// <summary>
/// Calculates the old coordinates for a point when the current point is the new reference (0, 0) of the sphere.
/// This is the inverse operation of <see cref="GetNewCoordinates(LatLonCoordinates)"/>.
/// </summary>
/// <param name="coordinates">The new coordinates to revert to the old ones.</param>
/// <returns>The old coordinates of the point that had coordinates <paramref name="coordinates"/> in the sphere when the reference was the current point.</returns>
/// <remarks>This only works for a sphere (don't use it for a geoide)!</remarks>
public LatLonCoordinates GetOldCoordinates(LatLonCoordinates coordinates)
{
double
lat = coordinates.Latitude.FixCoordinate(true) * Math.PI / 180d,
lon = coordinates.Longitude.FixCoordinate(false) * Math.PI / 180d;
double
cosLat = Math.Cos(lat);
double
x1 = Math.Cos(lon) * cosLat,
y1 = Math.Sin(lon) * cosLat,
z1 = Math.Sin(lat);
double
theta = (0 - this.Latitude) * Math.PI / 180d;
double
cosTheta = Math.Cos(theta),
sinTheta = Math.Sin(theta);
double
x2 = cosTheta * x1 + sinTheta * z1,
y2 = y1,
z2 = cosTheta * z1 - sinTheta * x1;
double
newLat = Math.Asin(z2),
newLon = Math.Atan2(y2, x2);
return(new LatLonCoordinates()
{
Latitude = newLat * 180d / Math.PI,
Longitude = newLon * 180d / Math.PI + this.Longitude
});
}
public LineCrossType GetLineCrossType(LatLonCoordinates point1, LatLonCoordinates point2)
{
throw new NotImplementedException();
/*
* This will be rather complicated: consider a map centered on a pole...
*/
}
/// <summary>
/// Checks whether a point is within these limits.
/// </summary>
/// <param name="coordinates">The point to test.</param>
/// <returns>true if <paramref name="coordinates"/> is within these limits, false otherwise.</returns>
public bool Contains(LatLonCoordinates coordinates)
{
return
(Math.Abs(coordinates.Latitude.FixCoordinate(true) - this.CenterLatitude) <= (this.LatitudeSpan / 2) &&
Math.Abs(coordinates.Longitude.FixCoordinate(true) - this.CenterLongitude) <= (this.LongitudeSpan / 2));
}
private static bool equals(LatLonCoordinates x, LatLonCoordinates y)
{
return(System.Object.ReferenceEquals(x, y) || (x?.Equals(y) ?? false));
}
