// 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>
/// <param name="latitude">The latitude.</param>
/// <param name="longitude">The longitude.</param>
/// <param name="n">The accuracy, used to divide the lat/lon space.</param>
/// <returns></returns>
public static ulong HilbertDistance(float latitude, float longitude, int n)
{
// calculate x, y.
ulong x = (ulong)(((longitude + 180) / 360.0) * n);
ulong y = (ulong)(((latitude + 90) / 180.0) * n);
// calculate hilbert value for x-y and n.
return(HilbertCurve.xy2d(n, x, y));
}
private void GenerateLayout()
{
int initialD = HilbertCurve.xy2d(n, initialHilbertTile.x, initialHilbertTile.y);
int i = initialD;
int maxSteps = n * n - 1;
Connections direction = Connections.None;
List <List <int2> > unconnectedPaths = new List <List <int2> >();
List <int2> currentPath = new List <int2>();
int2 currentTile = new int2(initialHilbertTile.x, initialHilbertTile.y);
currentPath.Add(Hilbert2Layout(currentTile));
while (i < maxSteps)
{
int2 nextTile = HilbertCurve.d2xy(n, i + 1);
if (IsInsideOffsetFrame(nextTile.x, nextTile.y))
{
direction = GetDirection(currentTile, nextTile);
if (direction != Connections.None) // we can connect currentTile and nextTile directly.
{
int2 layoutTile = Hilbert2Layout(currentTile);
layoutConnections[layoutTile.x, layoutTile.y] |= direction;
}
else
{
unconnectedPaths.Add(currentPath);
currentPath = new List <int2>();
}
currentPath.Add(Hilbert2Layout(nextTile));
currentTile = nextTile;
}
i++;
}
unconnectedPaths.Add(currentPath);
ConnectUnconnectedPaths(unconnectedPaths);
exit = currentTile;
}