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);
}
}
}
