/// <summary>
/// Builds the potential shortcuts.
/// </summary>
public static void BuildShortcuts <T>(this VertexInfo <T> vertexinfo, WeightHandler <T> weightHandler)
where T : struct
{
var vertex = vertexinfo.Vertex;
var shortcuts = vertexinfo.Shortcuts;
// loop over all edge-pairs once.
var shortcut = new Shortcut <T>()
{
Backward = weightHandler.Infinite,
Forward = weightHandler.Infinite
};
var shortcutEdge = new OriginalEdge();
for (var j = 1; j < vertexinfo.Count; j++)
{
var edge1 = vertexinfo[j];
var edge1Weight = weightHandler.GetEdgeWeight(edge1);
shortcutEdge.Vertex1 = edge1.Neighbour;
// figure out what witness paths to calculate.
for (var k = 0; k < j; k++)
{
var edge2 = vertexinfo[k];
var edge2Weight = weightHandler.GetEdgeWeight(edge2);
shortcutEdge.Vertex2 = edge2.Neighbour;
if (!(edge1Weight.Direction.B && edge2Weight.Direction.F) &&
!(edge1Weight.Direction.F && edge2Weight.Direction.B))
{ // impossible route, do nothing.
continue;
}
shortcut.Backward = weightHandler.Infinite;
shortcut.Forward = weightHandler.Infinite;
if (edge1Weight.Direction.B && edge2Weight.Direction.F)
{
shortcut.Forward = weightHandler.Add(edge1Weight.Weight, edge2Weight.Weight);
}
if (edge1Weight.Direction.F && edge2Weight.Direction.B)
{
shortcut.Backward = weightHandler.Add(edge1Weight.Weight, edge2Weight.Weight);
}
shortcuts.AddOrUpdate(shortcutEdge, shortcut, weightHandler);
}
}
}
/// <summary>
/// Adds edges relevant for contraction to the given vertex info, assuming it's empty.
/// </summary>
public static void AddRelevantEdges <T>(this VertexInfo <T> vertexInfo, DirectedMetaGraph.EdgeEnumerator enumerator)
where T : struct
{
System.Diagnostics.Debug.Assert(vertexInfo.Count == 0);
var vertex = vertexInfo.Vertex;
enumerator.MoveTo(vertex);
while (enumerator.MoveNext())
{
if (enumerator.Neighbour == vertex)
{
continue;
}
vertexInfo.Add(enumerator.Current);
}
}
public static bool RemoveShortcuts <T>(this VertexInfo <T> vertexInfo, DirectedGraph witnessGraph, WeightHandler <T> weightHandler)
where T : struct
{
var witnessGraphEnumerator = witnessGraph.GetEdgeEnumerator();
List <Tuple <OriginalEdge, Shortcut <T> > > toUpdate = null;
foreach (var pair in vertexInfo.Shortcuts)
{
var edge = pair.Key;
if (edge.Vertex1 >= witnessGraph.VertexCount ||
edge.Vertex2 >= witnessGraph.VertexCount)
{
continue;
}
var shortcut = pair.Value;
var shortcutForward = weightHandler.GetMetric(shortcut.Forward);
var shortcutBackward = weightHandler.GetMetric(shortcut.Backward);
var witnessedForward = float.MaxValue;
var witnessedBackward = float.MaxValue;
if (edge.Vertex1 < edge.Vertex2)
{
witnessGraphEnumerator.MoveTo(edge.Vertex1);
while (witnessGraphEnumerator.MoveNext())
{
if (witnessGraphEnumerator.Neighbour == edge.Vertex2)
{
witnessedForward = DirectedGraphExtensions.FromData(witnessGraphEnumerator.Data0);
witnessedBackward = DirectedGraphExtensions.FromData(witnessGraphEnumerator.Data1);
break;
}
}
}
else
{
witnessGraphEnumerator.MoveTo(edge.Vertex2);
while (witnessGraphEnumerator.MoveNext())
{
if (witnessGraphEnumerator.Neighbour == edge.Vertex1)
{
witnessedBackward = DirectedGraphExtensions.FromData(witnessGraphEnumerator.Data0);
witnessedForward = DirectedGraphExtensions.FromData(witnessGraphEnumerator.Data1);
break;
}
}
}
// check forward.
var hasUpdates = false;
if (shortcutForward > 0 && shortcutForward < float.MaxValue &&
shortcutForward - FastHierarchyBuilder <float> .E > witnessedForward)
{
shortcut.Forward = weightHandler.Infinite;
hasUpdates = true;
}
if (shortcutBackward > 0 && shortcutBackward < float.MaxValue &&
shortcutBackward - FastHierarchyBuilder <float> .E > witnessedBackward)
{
shortcut.Backward = weightHandler.Infinite;
hasUpdates = true;
}
if (hasUpdates)
{
if (toUpdate == null)
{
toUpdate = new List <Tuple <OriginalEdge, Shortcut <T> > >();
}
toUpdate.Add(new Tuple <OriginalEdge, Shortcut <T> >(edge, shortcut));
}
}
if (toUpdate != null)
{
foreach (var update in toUpdate)
{
vertexInfo.Shortcuts[update.Item1] = update.Item2;
}
return(true);
}
return(false);
}
/// <summary>
/// Calculates the priority of this vertex.
/// </summary>
public static float Priority <T>(this VertexInfo <T> vertexInfo, DirectedMetaGraph graph, WeightHandler <T> weightHandler, float differenceFactor, float contractedFactor,
float depthFactor, float weightDiffFactor = 1)
where T : struct
{
var vertex = vertexInfo.Vertex;
var removed = vertexInfo.Count;
var added = 0;
//var removedWeight = 0f;
//var addedWeight = 0f;
foreach (var shortcut in vertexInfo.Shortcuts)
{
var shortcutForward = weightHandler.GetMetric(shortcut.Value.Forward);
var shortcutBackward = weightHandler.GetMetric(shortcut.Value.Backward);
int localAdded, localRemoved;
if (shortcutForward > 0 && shortcutForward < float.MaxValue &&
shortcutBackward > 0 && shortcutBackward < float.MaxValue &&
System.Math.Abs(shortcutForward - shortcutBackward) < HierarchyBuilder.E)
{ // add two bidirectional edges.
graph.TryAddOrUpdateEdge(shortcut.Key.Vertex1, shortcut.Key.Vertex2, shortcutForward, null, vertex,
out localAdded, out localRemoved);
added += localAdded;
removed += localRemoved;
graph.TryAddOrUpdateEdge(shortcut.Key.Vertex2, shortcut.Key.Vertex1, shortcutForward, null, vertex,
out localAdded, out localRemoved);
added += localAdded;
removed += localRemoved;
//added += 2;
//addedWeight += shortcutForward;
//addedWeight += shortcutBackward;
}
else
{
if (shortcutForward > 0 && shortcutForward < float.MaxValue)
{
graph.TryAddOrUpdateEdge(shortcut.Key.Vertex1, shortcut.Key.Vertex2, shortcutForward, true, vertex,
out localAdded, out localRemoved);
added += localAdded;
removed += localRemoved;
graph.TryAddOrUpdateEdge(shortcut.Key.Vertex2, shortcut.Key.Vertex1, shortcutForward, false, vertex,
out localAdded, out localRemoved);
added += localAdded;
removed += localRemoved;
//added += 2;
//addedWeight += shortcutForward;
//addedWeight += shortcutForward;
}
if (shortcutBackward > 0 && shortcutBackward < float.MaxValue)
{
graph.TryAddOrUpdateEdge(shortcut.Key.Vertex1, shortcut.Key.Vertex2, shortcutBackward, false, vertex,
out localAdded, out localRemoved);
added += localAdded;
removed += localRemoved;
graph.TryAddOrUpdateEdge(shortcut.Key.Vertex2, shortcut.Key.Vertex1, shortcutBackward, true, vertex,
out localAdded, out localRemoved);
added += localAdded;
removed += localRemoved;
//added += 2;
//addedWeight += shortcutBackward;
//addedWeight += shortcutBackward;
}
}
}
//for (var e = 0; e < vertexInfo.Count; e++)
//{
// var w = weightHandler.GetEdgeWeight(vertexInfo[e]);
// var wMetric = weightHandler.GetMetric(w.Weight);
// if (w.Direction.F)
// {
// removedWeight += wMetric;
// }
// if (w.Direction.B)
// {
// removedWeight += wMetric;
// }
//}
var weigthDiff = 1f;
//if (removedWeight != 0)
//{
// weigthDiff = removedWeight;
//}
return((differenceFactor * (added - removed) + (depthFactor * vertexInfo.Depth) +
(contractedFactor * vertexInfo.ContractedNeighbours)) * (weigthDiff * weightDiffFactor));
}
