private void HandleMergeVertex(TVertex vertex)
{
#if DEBUG
int hs = helpers.Count;
#endif
Debug.Assert(GetVertexType(vertex) == VertexType.Merge);
// Deal with connections to the right of the above-incident vertices
// Connect each above indicent edge to its helper, if that
// helper was a merge vertex. And remove these above-incident edges
// from the sweep line status (helpers). This is to complete the regularisation
// of merge vertices encountered earlier in the sweep.
var aboveEdges = meshUtilities.AboveEdges(vertex).ToList();
foreach (EdgeBase edge in aboveEdges)
{
if (helpers.ContainsKey(edge))
{
TVertex helper = helpers[edge];
if (GetVertexType(helper) == VertexType.Merge)
{
DiagonalInserterDelegate(mesh, vertex, helper);
}
}
}
// Remove the above incident-edges from the sweep
foreach (EdgeBase edge in aboveEdges)
{
bool removed = helpers.Remove(edge);
Debug.Assert(removed);
}
// Deal with connections to the left of the above-incident vertices
KeyValuePair <EdgeBase, TVertex>?directlyLeft = DirectlyLeftOf(sweeplineUtilities.RightMost(aboveEdges));
if (directlyLeft.HasValue)
{
if (helpers.ContainsKey(directlyLeft.Value.Key))
{
TVertex helper1 = helpers[directlyLeft.Value.Key];
if (GetVertexType(helper1) == VertexType.Merge)
{
DiagonalInserterDelegate(mesh, vertex, helper1);
}
helpers[directlyLeft.Value.Key] = vertex;
}
}
#if DEBUG
// There should be no below edges from a merge-vertex
var belowEdges = meshUtilities.BelowEdges(vertex);
Debug.Assert(belowEdges.Count() == 0);
Debug.Assert(helpers.Count == hs - aboveEdges.Count() + belowEdges.Count());
#endif
}
// TODO: This could be an iterator
private List <ChainVertex> TraceRightAndDown(TVertex top)
{
TVertex vertex = top;
List <ChainVertex> result = new List <ChainVertex>();
IEnumerable <EdgeBase> belowEdges;
while ((belowEdges = BelowEdges(vertex)).Count() > 0)
{
EdgeBase edge = sweeplineUtilities.RightMost(belowEdges);
TVertex lower = meshUtilities.LowerVertex(edge);
result.Add(new ChainVertex(lower, Chain.Right));
vertex = lower;
}
return(result);
}