The first step of our layout algorithm is to assign each node to a level. Nodes with no parents are placed on the first level. Next, direct children of those nodes on the first level are placed on the second level. Third level nodes are the direct children of nodes of the first and second levels. This process continues until all nodes have been assigned a level. If a given node's children are not placed on the level directly below them, we use virtual nodes to assure connections are made for nodes which are separated by more than one level.
Copyright © 1994, 1995 Keith B. Gallagher, Bradley M. Kuhn, Dennis J. Smith.
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