public static long HilbertDistance(float latitude, float longitude, long n)
{
long x = (long)(((double)longitude + 180.0) / 360.0 * (double)n);
if (x >= n)
{
x = n - 1L;
}
long y = (long)(((double)latitude + 90.0) / 180.0 * (double)n);
if (y >= n)
{
y = n - 1L;
}
return(HilbertCurve.xy2d(n, x, y));
}
// DISCLAIMER: some of this stuff is straight from wikipedia:
// http://en.wikipedia.org/wiki/Hilbert_curve#Applications_and_mapping_algorithms
/// <summary>
/// Calculates hilbert distance.
/// </summary>
/// <returns></returns>
public static long HilbertDistance(float latitude, float longitude, long n)
{
// calculate x, y.
var x = (long)((((double)longitude + 180.0) / 360.0) * n);
if (x >= n)
{
x = n - 1;
}
var y = (long)((((double)latitude + 90.0) / 180.0) * n);
if (y >= n)
{
y = n - 1;
}
// calculate hilbert value for x-y and n.
return(HilbertCurve.xy2d(n, x, y));
}