internal override bool Remove(BroadPhaseEntry entry, out LeafNode leafNode, out Node replacementNode)
{
replacementNode = null;
if (element == entry)
{
leafNode = this;
return(true);
}
leafNode = null;
return(false);
}
internal override bool TryToInsert(LeafNode node, out Node treeNode)
{
InternalNode newTreeNode = InternalNode.nodePool.Take();
BoundingBox.CreateMerged(ref BoundingBox, ref node.BoundingBox, out newTreeNode.BoundingBox);
Vector3 offset;
Vector3.Subtract(ref newTreeNode.BoundingBox.Max, ref newTreeNode.BoundingBox.Min, out offset);
newTreeNode.currentVolume = offset.X * offset.Y * offset.Z;
newTreeNode.childA = this;
newTreeNode.childB = node;
treeNode = newTreeNode;
return(true);
}
internal override bool RemoveFast(BroadPhaseEntry entry, out LeafNode leafNode, out Node replacementNode)
{
//The fastremove leaf node procedure is identical to the brute force approach.
//We don't need to perform any bounding box test here; if they're equal, they're equal!
replacementNode = null;
if (element == entry)
{
leafNode = this;
return(true);
}
leafNode = null;
return(false);
}
internal override bool RemoveFast(BroadPhaseEntry entry, out LeafNode leafNode, out Node replacementNode)
{
//Only bother checking deeper in the path if the entry and child have overlapping bounding boxes.
bool intersects;
childA.BoundingBox.Intersects(ref entry.boundingBox, out intersects);
if (intersects && childA.RemoveFast(entry, out leafNode, out replacementNode))
{
if (childA.IsLeaf)
{
replacementNode = childB;
}
else
{
//It was not a leaf node, but a child found the leaf.
//Change the child to the replacement node.
childA = replacementNode;
replacementNode = this; //We don't need to be replaced!
}
return(true);
}
childB.BoundingBox.Intersects(ref entry.boundingBox, out intersects);
if (intersects && childB.RemoveFast(entry, out leafNode, out replacementNode))
{
if (childB.IsLeaf)
{
replacementNode = childA;
}
else
{
//It was not a leaf node, but a child found the leaf.
//Change the child to the replacement node.
childB = replacementNode;
replacementNode = this; //We don't need to be replaced!
}
return(true);
}
replacementNode = this;
leafNode = null;
return(false);
}
/// <summary>
/// Adds an entry to the hierarchy.
/// </summary>
/// <param name="entry">Entry to add.</param>
public override void Add(BroadPhaseEntry entry)
{
base.Add(entry);
//Entities do not set up their own bounding box before getting stuck in here. If they're all zeroed out, the tree will be horrible.
Vector3 offset;
Vector3.Subtract(ref entry.boundingBox.Max, ref entry.boundingBox.Min, out offset);
if (offset.X * offset.Y * offset.Z == 0)
{
entry.UpdateBoundingBox();
}
//Could buffer additions to get a better construction in the tree.
LeafNode node = leafNodes.Take();
node.Initialize(entry);
if (root == null)
{
//Empty tree. This is the first and only node.
root = node;
}
else
{
if (root.IsLeaf) //Root is alone.
{
root.TryToInsert(node, out root);
}
else
{
BoundingBox.CreateMerged(ref node.BoundingBox, ref root.BoundingBox, out root.BoundingBox);
InternalNode internalNode = (InternalNode)root;
Vector3.Subtract(ref root.BoundingBox.Max, ref root.BoundingBox.Min, out offset);
internalNode.currentVolume = offset.X * offset.Y * offset.Z;
//internalNode.maximumVolume = internalNode.currentVolume * InternalNode.MaximumVolumeScale;
//The caller is responsible for the merge.
Node treeNode = root;
while (!treeNode.TryToInsert(node, out treeNode))
{
; //TryToInsert returns the next node, if any, and updates node bounding box.
}
}
}
}
internal override bool Remove(BroadPhaseEntry entry, out LeafNode leafNode, out Node replacementNode)
{
if (childA.Remove(entry, out leafNode, out replacementNode))
{
if (childA.IsLeaf)
{
replacementNode = childB;
}
else
{
//It was not a leaf node, but a child found the leaf.
//Change the child to the replacement node.
childA = replacementNode;
replacementNode = this; //We don't need to be replaced!
}
return(true);
}
if (childB.Remove(entry, out leafNode, out replacementNode))
{
if (childB.IsLeaf)
{
replacementNode = childA;
}
else
{
//It was not a leaf node, but a child found the leaf.
//Change the child to the replacement node.
childB = replacementNode;
replacementNode = this; //We don't need to be replaced!
}
return(true);
}
replacementNode = this;
return(false);
}
internal override bool TryToInsert(LeafNode node, out Node treeNode)
{
//Since we are an internal node, we know we have two children.
//Regardless of what kind of nodes they are, figure out which would be a better choice to merge the new node with.
//Use the path which produces the smallest 'volume.'
BoundingBox mergedA, mergedB;
BoundingBox.CreateMerged(ref childA.BoundingBox, ref node.BoundingBox, out mergedA);
BoundingBox.CreateMerged(ref childB.BoundingBox, ref node.BoundingBox, out mergedB);
Vector3 offset;
float originalAVolume, originalBVolume;
Vector3.Subtract(ref childA.BoundingBox.Max, ref childA.BoundingBox.Min, out offset);
originalAVolume = offset.X * offset.Y * offset.Z;
Vector3.Subtract(ref childB.BoundingBox.Max, ref childB.BoundingBox.Min, out offset);
originalBVolume = offset.X * offset.Y * offset.Z;
float mergedAVolume, mergedBVolume;
Vector3.Subtract(ref mergedA.Max, ref mergedA.Min, out offset);
mergedAVolume = offset.X * offset.Y * offset.Z;
Vector3.Subtract(ref mergedB.Max, ref mergedB.Min, out offset);
mergedBVolume = offset.X * offset.Y * offset.Z;
//Could use factor increase or absolute difference
if (mergedAVolume - originalAVolume < mergedBVolume - originalBVolume)
{
//merging A produces a better result.
if (childA.IsLeaf)
{
InternalNode newChildA = nodePool.Take();
newChildA.BoundingBox = mergedA;
newChildA.childA = childA;
newChildA.childB = node;
newChildA.currentVolume = mergedAVolume;
childA = newChildA;
treeNode = null;
return(true);
}
childA.BoundingBox = mergedA;
InternalNode internalNode = (InternalNode)childA;
internalNode.currentVolume = mergedAVolume;
treeNode = childA;
return(false);
}
//merging B produces a better result.
if (childB.IsLeaf)
{
//Target is a leaf! Return.
InternalNode newChildB = nodePool.Take();
newChildB.BoundingBox = mergedB;
newChildB.childA = node;
newChildB.childB = childB;
newChildB.currentVolume = mergedBVolume;
childB = newChildB;
treeNode = null;
return(true);
}
{
childB.BoundingBox = mergedB;
treeNode = childB;
InternalNode internalNode = (InternalNode)childB;
internalNode.currentVolume = mergedBVolume;
return(false);
}
}
internal abstract bool RemoveFast(BroadPhaseEntry entry, out LeafNode leafNode, out Node replacementNode);
internal abstract bool TryToInsert(LeafNode node, out Node treeNode);