private void CondenseTree(Node<T> l)
{
// CT1 [Initialize] Set n=l. Set the list of eliminated
// nodes to be empty.
var n = l;
// TIntStack eliminatedNodeIds = new TIntStack();
var eliminatedNodeIds = new Stack<int>();
// CT2 [Find parent entry] If N is the root, go to CT6. Otherwise
// let P be the parent of N, and let En be N's entry in P
while (n.level != treeHeight)
{
var parent = GetNode(parents.Pop());
var parentEntry = parentsEntry.Pop();
// CT3 [Eliminiate under-full node] If N has too few entries,
// delete En from P and add N to the list of eliminated nodes
if (n.entryCount < minNodeEntries)
{
parent.DeleteEntry(parentEntry, minNodeEntries);
eliminatedNodeIds.Push(n.nodeId);
}
else
{
// CT4 [Adjust covering rectangle] If N has not been eliminated,
// adjust EnI to tightly contain all entries in N
if (!n.mbr.Equals(parent.entries[parentEntry]))
{
oldRectangle.Set(parent.entries[parentEntry]._min, parent.entries[parentEntry]._max);
parent.entries[parentEntry].Set(n.mbr._min, n.mbr._max);
parent.RecalculateMBR(oldRectangle);
}
}
// CT5 [Move up one level in tree] Set N=P and repeat from CT2
n = parent;
}
// CT6 [Reinsert orphaned entries] Reinsert all entries of nodes in set Q.
// Entries from eliminated leaf nodes are reinserted in tree leaves as in
// Insert(), but entries from higher level nodes must be placed higher in
// the tree, so that leaves of their dependent subtrees will be on the same
// level as leaves of the main tree
while (eliminatedNodeIds.Count > 0)
{
var e = GetNode(eliminatedNodeIds.Pop());
for (var j = 0; j < e.entryCount; j++)
{
Add(e.entries[j], e.ids[j], e.level);
e.entries[j] = null;
}
e.entryCount = 0;
deletedNodeIds.Push(e.nodeId);
}
}
// oldRectangle is a rectangle that has just been deleted or made smaller.
// Thus, the MBR is only recalculated if the OldRectangle influenced the old MBR
internal void RecalculateMBR(Rectangle deletedRectangle)
{
if (mbr.EdgeOverlaps(deletedRectangle))
{
mbr.Set(entries[0]._min, entries[0]._max);
for (var i = 1; i < entryCount; i++)
{
mbr.Add(entries[i]);
}
}
}