protected void sortVertices() {
layerPartition =
new DefaultLayerPartition(digraph, rankFunction, vertexShape, subgraphPartition);
layerPartition.breadthFirstSort();
int crossingCount = layerPartition.countCrossings();
Map orderSnapshot = layerPartition.makeOrderSnapshot();
boolean lastIsBest = true;
for (int i = 0; i < sortIterationCount; i++) {
if (i % 2 == 0) layerPartition.sortDownByMedian();
else layerPartition.sortUpByMedian();
int newCrossingCount = layerPartition.countCrossings();
if (newCrossingCount < crossingCount) {
crossingCount = newCrossingCount;
orderSnapshot = layerPartition.makeOrderSnapshot();
lastIsBest = true;
} else if (newCrossingCount > crossingCount) lastIsBest = false;
}
if (!lastIsBest) layerPartition.restoreOrder(orderSnapshot);
layerPartition.refreshIndices();
}
