private void Initialize() { sweepline = new OA_Sweepline(); eventQueue = new RBTreeSet <OA_EventPoint>(OA_EventPoint.Compare); outputSubdivision = new DCEL_Subdivision(); foreach (DCEL_Subdivision inputSubdivision in inputSubdivisions) { foreach (DCEL_HalfEdge inputHalfEdge in inputSubdivision.HalfEdges.Keys) { OA_EventPoint upper = new OA_EventPoint(inputHalfEdge.Origin.Position); OA_EventPoint lower = new OA_EventPoint(inputHalfEdge.Destination.Position); //We want to take only one of the twins from every pair of half edges. if (upper.CompareTo(lower) > 0) { continue; } RBTreeSetNode <OA_EventPoint> upper_node = new RBTreeSetNode <OA_EventPoint>(upper); RBTreeSetNode <OA_EventPoint> lower_node = new RBTreeSetNode <OA_EventPoint>(lower); //If we didn't add the newly created event point, it already existed. if (!eventQueue.Add(ref upper_node)) { upper = upper_node.Key; } if (!eventQueue.Add(ref lower_node)) { lower = lower_node.Key; } OA_Segment segment = new OA_Segment(sweepline); segment.Source.Add(new OA_Source <DCEL_HalfEdge>(inputSubdivision, inputHalfEdge)); segment.Upper = upper; segment.Lower = lower; //***May be adding a duplicate if segment is in both subdivisions! upper.UpperList.Add(segment); if (!upper.Source.Any(OA_Source <DCEL_Vertex> .IsFrom(inputSubdivision))) { upper.Source.Add(new OA_Source <DCEL_Vertex>(inputSubdivision, inputHalfEdge.Origin)); } if (!lower.Source.Any(OA_Source <DCEL_Vertex> .IsFrom(inputSubdivision))) { lower.Source.Add(new OA_Source <DCEL_Vertex>(inputSubdivision, inputHalfEdge.Destination)); } } } foreach (OA_EventPoint eventPoint in eventQueue.Keys) { //***Remove those duplicates here, joining their source lists. eventPoint.UpperList.RemoveDuplicates(OA_Segment.CompareEndpoints, OA_Segment.JoinSource); } }
private void SetLeftPick(OA_EventPoint eventPoint) { RBTreeSetNode <OA_Segment> leftPick_node = sweepline.Status.FindMax(OA_Segment.IntersectsSweeplineLeftOfEventPointExclusive); if (leftPick_node != null) { eventPoint.LeftPick = leftPick_node.Key; } else { eventPoint.LeftPick = null; } }
private void HandleEventPoint(OA_EventPoint eventPoint) { AssertValidSweeplineStatus(); //Sweep to before the event point sweepline.IncidentEventPoint = eventPoint; sweepline.BeforeEventPoint = true; AssertValidSweeplineStatus(); if (phase == Phase.MergingPhase) { SetLeftPick(eventPoint); } //Determine all segments that contain the event point, and partition them List <OA_Segment> upperList = eventPoint.UpperList; List <OA_Segment> middleList; List <OA_Segment> lowerList; sweepline.Status .FindRange(OA_Segment.CompareSweeplineIntersectionToCurrentEventPoint).Select(node => node.Key) .Partition(OA_Segment.LowerIsCurrentEventPoint, out lowerList, out middleList); //upperList gets added, middleList gets reversed, lowerList gets removed EventPointTransition(upperList, middleList, lowerList); AssertValidSweeplineStatus(); switch (phase) { case Phase.SplittingPhase: HandleIntersection_SplittingPhase(eventPoint, upperList, middleList, lowerList); break; case Phase.MergingPhase: HandleIntersection_MergingPhase(eventPoint, upperList, middleList, lowerList); break; default: throw new Exception(); } AssertValidSweeplineStatus(); if (upperList.IsEmpty() && middleList.IsEmpty()) { RBTreeSetNode <OA_Segment> predecessorNode = sweepline.Status.FindMax(OA_Segment.IntersectsSweeplineLeftOfEventPointInclusive); RBTreeSetNode <OA_Segment> successorNode = sweepline.Status.FindMin(OA_Segment.IntersectsSweeplineRightOfEventPointInclusive); if (predecessorNode != null && successorNode != null) { FindNewEventPoint(predecessorNode.Key, successorNode.Key, eventPoint); } } else { var leftmostIntersectingNode = sweepline.Status.FindMin(OA_Segment.IntersectsSweeplineRightOfEventPointInclusive); var leftmostPredecessorNode = leftmostIntersectingNode.Predecessor; if (leftmostPredecessorNode != null) { FindNewEventPoint(leftmostPredecessorNode.Key, leftmostIntersectingNode.Key, eventPoint); } var rightmostIntersectingNode = sweepline.Status.FindMax(OA_Segment.IntersectsSweeplineLeftOfEventPointInclusive); var rightmostSuccessorNode = rightmostIntersectingNode.Successor; if (rightmostSuccessorNode != null) { FindNewEventPoint(rightmostIntersectingNode.Key, rightmostSuccessorNode.Key, eventPoint); } } }