/// <summary>
/// Creates the covering rectangle of the node that encloses
/// a point at a given depth in the index tree.
/// </summary>
/// <param name="p">The point of interest</param>
/// <param name="depth">The 0-based tree depth (specify 0 when dealing
/// with the root node)</param>
/// <returns>The covering rectangle enclosing the point at the requested depth</returns>
Extent CreateWindow(IPoint p, int depth)
{
if (depth == 0)
{
return(new Extent());
}
ulong x = SpatialIndex.ToUnsigned(p.Geometry.Easting.Microns);
ulong y = SpatialIndex.ToUnsigned(p.Geometry.Northing.Microns);
// The lower-left corner is given by masking out the low-order bits (neat)
ulong size = Node.SIZES[depth];
ulong mask = size ^ 0xFFFFFFFFFFFFFFFF;
ulong minx = (x & mask);
ulong miny = (y & mask);
ulong maxx = minx + size;
ulong maxy = miny + size;
Debug.Assert(maxx > minx);
Debug.Assert(maxy > miny);
return(new Extent(minx, miny, maxx, maxy));
}