private List createSubgraphs(PlanarGraph graph) {
List subgraphList = new ArrayList();
for (Iterator i = graph.getNodes().iterator(); i.hasNext(); ) {
Node node = (Node) i.next();
if (!node.isVisited()) {
BufferSubgraph subgraph = new BufferSubgraph();
subgraph.create(node);
subgraphList.add(subgraph);
}
}
/**
* Sort the subgraphs in descending order of their rightmost coordinate. This ensures that when
* the Polygons for the subgraphs are built, subgraphs for shells will have been built before
* the subgraphs for any holes they contain.
*/
Collections.sort(subgraphList, Collections.reverseOrder());
return subgraphList;
}
/**
* Because Delete Events have a link to their corresponding Insert event, it is possible to
* compute exactly the range of events which must be compared to a given Insert event object.
*/
private void prepareEvents() {
Collections.sort(events);
for (int i = 0; i < events.size(); i++) {
SweepLineEvent ev = (SweepLineEvent) events.get(i);
if (ev.isDelete()) {
ev.getInsertEvent().setDeleteEventIndex(i);
}
}
}