Interface BSPTree.LeafMerger<S extends Space>
 Type Parameters:
S
 Type of the space.
As explained in Bruce Naylor, John Amanatides and William
Thibault paper Merging
BSP Trees Yields Polyhedral Set Operations,
the operations on BSP trees
can be expressed as a
generic recursive merging operation where only the final part,
when one of the operand is a leaf, is specific to the real
operation semantics. For example, a tree representing a region
using a boolean attribute to identify inside cells and outside
cells would use four different objects to implement the final
merging phase of the four set operations union, intersection,
difference and symmetric difference (exclusive or).

Method Summary

Method Details

merge
BSPTree<S> merge(BSPTree<S> leaf, BSPTree<S> tree, BSPTree<S> parentTree, boolean isPlusChild, boolean leafFromInstance) Merge a leaf node and a tree node.This method is called at the end of a recursive merging resulting from a
tree1.merge(tree2, leafMerger)
call, when one of the subtrees involved is a leaf (i.e. when its cuthyperplane is null). This is the only place where the precise semantics of the operation are required. For all upper level nodes in the tree, the merging operation is only a generic partitioning algorithm.Since the final operation may be noncommutative, it is important to know if the leaf node comes from the instance tree (
tree1
) or the argument tree (tree2
). The third argument of the method is devoted to this. It can be ignored for commutative operations.The
BSPTree.insertInTree
method may be useful to implement this method. Parameters:
leaf
 leaf node (its cut hyperplane is guaranteed to be null)tree
 tree node (its cut hyperplane may be null or not)parentTree
 parent tree to connect to (may be null)isPlusChild
 if true and if parentTree is not null, the resulting tree should be the plus child of its parent, ignored if parentTree is nullleafFromInstance
 if true, the leaf node comes from the instance tree (tree1
) and the tree node comes from the argument tree (tree2
) Returns:
 the BSP tree resulting from the merging (may be one of the arguments)
