/// <summary>
/// halfEdge should be Upper->Lower so that the persistent half edges become:
/// o halfEdge (Upper->Lower) ==> (vertex->Lower)
/// o halfEdge.Twin (Lower->Upper) ==> (Lower->vertex)
/// And the two newly created half edges are (vertex->Upper) and (Upper->vertex).
/// </summary>
private static void SplitEdge(DCEL_Subdivision subdivision, DCEL_HalfEdge halfEdge, DCEL_Vertex vertex)
{
Debug.Assert(VecRat2.CompareReadingOrder(halfEdge.Origin.Position, halfEdge.Destination.Position) < 0);
DCEL_HalfEdge e1 = halfEdge;
DCEL_HalfEdge e2 = e1.Twin;
DCEL_HalfEdge e1_prev = e1.Prev;
DCEL_HalfEdge e2_next = e2.Next;
DCEL_Vertex e1_origin = e1.Origin;
DCEL_HalfEdge e1_top = new DCEL_HalfEdge();
DCEL_HalfEdge e2_top = new DCEL_HalfEdge();
DCEL_Helper.JoinTwin(e1_top, e2_top);
e1_top.IncidentFace = e1.IncidentFace;
e2_top.IncidentFace = e2.IncidentFace;
DCEL_Helper.JoinIncidentEdge(vertex, e2_top);
DCEL_Helper.JoinIncidentEdge(vertex, e1);
DCEL_Helper.JoinIncidentEdge(e1_origin, e1_top);
if (e2_next == e1)
{
DCEL_Helper.JoinNext(e2, e2_top);
DCEL_Helper.JoinNext(e2_top, e1_top);
DCEL_Helper.JoinNext(e1_top, e1);
}
else
{
DCEL_Helper.JoinPrevNext(e2, e2_top, e2_next);
DCEL_Helper.JoinPrevNext(e1_prev, e1_top, e1);
}
if (subdivision != null)
{
subdivision.HalfEdges.Add(new RBTreeSetNode <DCEL_HalfEdge>(e1_top));
subdivision.HalfEdges.Add(new RBTreeSetNode <DCEL_HalfEdge>(e2_top));
}
}
private void HandleIntersection_MergingPhase(OA_EventPoint eventPoint, List <OA_Segment> upperList, List <OA_Segment> middleList, List <OA_Segment> lowerList)
{
if (middleList.Count != 0)
{
throw new Exception("MergingPhase: Something went wrong in the SplittingPhase, because there is an intersection with nonempty middleList.");
}
//Dictionary<DCEL_Subdivision, DCEL_Vertex> vertexLookup = CreateSourceLookup(eventPoint);
//DCEL_Vertex mergedVertex = vertexLookup.Values.First();
DCEL_Vertex mergedVertex = eventPoint.Source.First().Element;
lowerList.Sort(AngleComparisonLowerList(mergedVertex.Position));
upperList.Sort(AngleComparisonUpperList(mergedVertex.Position));
//JoinNext all consecutive pairs around circle, and join origins to mergedVertex
{
//Outgoing half edges in CCW order
List <DCEL_HalfEdge> bothList = new List <DCEL_HalfEdge>();
bothList.AddRange(lowerList.Select(segment => segment.Source.First().Element.Twin));
bothList.AddRange(upperList.Select(segment => segment.Source.First().Element));
if (bothList.Count > 1)
{
DCEL_HalfEdge e, e_next;
for (int i = 1; i < bothList.Count; i++)
{
e = bothList[i].Twin;
e_next = bothList[i - 1];
DCEL_Helper.JoinNext(e, e_next);
}
e = bothList.First().Twin;
e_next = bothList.Last();
DCEL_Helper.JoinNext(e, e_next);
}
else
{
DCEL_HalfEdge e = bothList[0].Twin;
DCEL_HalfEdge e_next = e.Twin;
DCEL_Helper.JoinNext(e, e_next);
}
//Set the origins to the mergedVertex
foreach (DCEL_HalfEdge e in bothList)
{
e.Origin = mergedVertex;
}
mergedVertex.IncidentEdge = bothList.First();
}
outputSubdivision.Vertices.Add(new RBTreeSetNode <DCEL_Vertex>(mergedVertex));
foreach (OA_Segment upper in upperList)
{
DCEL_HalfEdge e = upper.Source.First().Element;
outputSubdivision.HalfEdges.Add(new RBTreeSetNode <DCEL_HalfEdge>(e));
outputSubdivision.HalfEdges.Add(new RBTreeSetNode <DCEL_HalfEdge>(e.Twin));
//HACK?/////////////////////////////////////////
e.IncidentFace = null;
e.Twin.IncidentFace = null;
//HACK?/////////////////////////////////////////
}
//Store the left pick for the mergedVertex
if (eventPoint.LeftPick != null)
{
leftPicksMap.Add(new RBTreeMapNode <DCEL_Vertex, DCEL_HalfEdge>(mergedVertex, eventPoint.LeftPick.Source.First().Element));
}
else
{
leftPicksMap.Add(new RBTreeMapNode <DCEL_Vertex, DCEL_HalfEdge>(mergedVertex, null));
}
}