/// <summary>
/// Increases the height when a split has propagated to the root node (in other words, the root node had to be split).
/// </summary>
/// <param name="rightRoot">The newly created sibling for the root node.</param>
private void IncreaseHeight(HilbertNode rightRoot)
{
if (rightRoot == null)
{
return;
}
HilbertNode newRoot = new HilbertNode(this.MaxChildren);
newRoot.AddChild(this.Root);
newRoot.AddChild(rightRoot);
this.Root = newRoot;
this.Height++;
}
/// <summary>
/// Adjusts the tree ascending from the leaf level up to the root.
/// </summary>
/// <param name="node">The node where the overflow happened.</param>
/// <param name="newNode">The new node, if a split was inevitable in <see cref="HandleOverflow(HilbertNode, HilbertNode)"/>, otherwise it's <c>null</c>.</param>
/// <returns>The new <see cref="HilbertNode"/> on the root level, if the root node had to be split.</returns>
private HilbertNode AdjustTree(HilbertNode node, HilbertNode newNode = null)
{
while (node != this.Root)
{
// propagate node split upward
HilbertNode nParent = (HilbertNode)node.Parent;
HilbertNode pParent = null;
if (newNode != null)
{
if (this.IsFull(nParent))
{
pParent = this.HandleOverflow(nParent, newNode);
}
else
{
nParent.AddChild(newNode);
}
}
// update MBR and LHV in parent level
nParent.CorrectBounding();
nParent.Children?.Sort(this.comparer);
nParent.LargestHilbertValue =
nParent.ChildrenCount == 0 ? new BigInteger(-1) :
((HilbertNode)nParent.Children[nParent.ChildrenCount - 1]).LargestHilbertValue;
node = nParent;
newNode = pParent;
}
return(newNode);
}
/// <summary>
/// Adds a geometry by creating a new leaf node.
/// </summary>
/// <param name="geometry">The geometry to be added.</param>
protected override void AddGeometry(IBasicGeometry geometry)
{
HilbertNode leaf = new HilbertNode(geometry, this.GetHilbertValue(geometry));
HilbertNode leafContainer = this.ChooseLeafContainer(leaf);
if (leafContainer == this.Root && leafContainer.ChildrenCount == 0)
{
this.Height = 1;
}
HilbertNode newNode = null;
if (!this.IsFull(leafContainer))
{
leafContainer.AddChild(leaf);
}
else
{
newNode = this.HandleOverflow(leafContainer, leaf);
}
HilbertNode rightRoot = this.AdjustTree(leafContainer, newNode);
this.IncreaseHeight(rightRoot);
}