public CellPairCollection <T> FollowBoundaryAndCollectCandidates(IEnumerable <Edge <T> > periodicEdges)
{
LinkedListDictionary <int, List <Edge <T> > > edges = DivideIntoBoundaries(periodicEdges);
Debug.Assert(edges.Count % 2 == 0);
CellPairCollection <T> candidates = new CellPairCollection <T>();
while (edges.Count > 0)
{
List <Edge <T> > boundary = edges.First().Value;
int boundaryNumber = edges.First().Key;
Position[] positions = new Position[boundary.Count];
for (int i = 0; i < boundary.Count; ++i)
{
Edge <T> edge = boundary[i];
if (NodeIsOnRightSideOfEdge(edge.Cell.Node, edge))
{
if (edge.Twin.Cell.Node != null && NodeIsOnRightSideOfEdge(edge.Twin.Cell.Node, edge))
{
positions[i] = Position.right;
candidates.AddOuterSplitCell(edge.Cell, edge.BoundaryEdgeNumber);
}
else
{
positions[i] = Position.rightUnsplit;
candidates.AddOuterUnsplitCell(edge.Cell, edge.BoundaryEdgeNumber);
}
}
else
{
if (edge.Twin.Cell.Node != null && !NodeIsOnRightSideOfEdge(edge.Twin.Cell.Node, edge))
{
positions[i] = Position.left;
candidates.AddInnerSplitCell(edge.Cell, edge.BoundaryEdgeNumber);
}
else
{
positions[i] = Position.leftUnsplit;
candidates.AddInnerUnsplitCell(edge.Cell, edge.BoundaryEdgeNumber);
}
}
}
edges.Remove(boundaryNumber);
boundaryNumber = map.PeriodicBoundaryCorrelation[boundaryNumber];
boundary = edges[boundaryNumber];
for (int i = 0; i < boundary.Count; ++i)
{
Edge <T> edge = boundary[i];
switch (positions[boundary.Count - 1 - i])
{
case Position.left:
candidates.AddOuterSplitCell(edge.Cell, edge.BoundaryEdgeNumber);
break;
case Position.right:
candidates.AddInnerSplitCell(edge.Cell, edge.BoundaryEdgeNumber);
break;
case Position.leftUnsplit:
candidates.AddOuterUnsplitCell(edge.Cell, edge.BoundaryEdgeNumber);
break;
case Position.rightUnsplit:
candidates.AddInnerUnsplitCell(edge.Cell, edge.BoundaryEdgeNumber);
break;
default:
throw new Exception();
}
}
edges.Remove(boundaryNumber);
}
return(candidates);
}
