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
}
/// <summary>
/// Find the edges which are above-indicent to the given vertex and
/// indicent to the face we are triangulating
/// </summary>
/// <param name="vertex"></param>
/// <returns></returns>
private IEnumerable <EdgeBase> AboveEdges(TVertex vertex)
{
return(meshUtilities.AboveEdges(vertex).Where(e => e.Faces.First == face ||
e.Faces.Second == face));
}