public MapItemQuadTreeNode(MapItemQuadTreeNode parent, int childIdx)
{
Parent = parent;
if (Parent == null)
{
Rect = new Rect(0, 0, 1, 1);
ZoomLevel = 0;
X = Y = 0L;
}
else
{
Rect = parent.GetChildRect(childIdx);
ZoomLevel = parent.ZoomLevel + 1;
X = (Parent.X << 1) + (childIdx % 2);
Y = (Parent.Y << 1) + (childIdx / 2);
}
_Children = new MapItemQuadTreeNode[4];
_Items = new HashSet<MapItem>();
}
