private static void FindNewEvent(Segment s1, Segment s2, EventPoint eventPoint, RBTreeMap <EventPoint, LinkedList <Segment> > eventQueue)
{
//If two segments intersect below the sweep line, or on it and
//to the right of the current event point, and the intersection
//is not yet present as an event in Q:
//then insert a new event point in Q for this intersection
VecRat2 pointIntersection = new VecRat2();
SegRat2 segmentIntersection = new SegRat2();
//bool intersectionExists = Segment.ComputeIntersection(s1, s2, out pointIntersection);
//if (intersectionExists)
SegmentIntersectionType result = GeomAid.SegmentIntersection(s1.ToSegRat2(), s2.ToSegRat2(), ref pointIntersection, ref segmentIntersection);
if (result == SegmentIntersectionType.Point)
{
EventPoint newEventPoint = new EventPoint(null);
newEventPoint.Position = pointIntersection;
if (eventPoint.CompareTo(newEventPoint) < 0 && !eventQueue.ContainsKey(newEventPoint))
{
LinkedList <Segment> upperList = new LinkedList <Segment>();
eventQueue.Add(new RBTreeMapNode <EventPoint, LinkedList <Segment> >(newEventPoint, upperList));
}
}
else if (result == SegmentIntersectionType.Segment)
{
throw new NotImplementedException("Didn't think this would ever happen?!");
}
}
public static LinkedList <LineSegmentIntersection> FindIntersections(IEnumerable <DCEL_HalfEdge> lineSegments)
{
LinkedList <LineSegmentIntersection> result = new LinkedList <LineSegmentIntersection>();
Sweepline sweepline = new Sweepline();
RBTreeMap <EventPoint, LinkedList <Segment> > eventQueue = new RBTreeMap <EventPoint, LinkedList <Segment> >((x, y) => x.CompareTo(y));
var segments = lineSegments.Where(lineSegment => lineSegment.Origin.Position != lineSegment.Destination.Position)
.Select(lineSegment => new Segment(lineSegment, sweepline));
//segments = FixOverlappingSegments(segments);
foreach (var segment in segments)
{
var node = eventQueue.Find(segment.Upper);
LinkedList <Segment> upperList = (node != null ? node.Value : null);
if (upperList == null)
{
upperList = new LinkedList <Segment>();
eventQueue.Add(new RBTreeMapNode <EventPoint, LinkedList <Segment> >(new EventPoint(segment.Upper), upperList));
}
upperList.AddLast(segment);
if (!eventQueue.ContainsKey(segment.Lower))
{
eventQueue.Add(new RBTreeMapNode <EventPoint, LinkedList <Segment> >(new EventPoint(segment.Lower), new LinkedList <Segment>()));
}
}
RBTreeSet <Segment> status = new RBTreeSet <Segment>((x, y) => x.CompareTo(y));
while (eventQueue.Count > 0)
{
var pair = eventQueue.MinNode;
eventQueue.RemoveMin();
EventPoint nextEventPoint = pair.Key;
LinkedList <Segment> upperList = pair.Value;
LineSegmentIntersection reportedIntersection;
HandleEventPoint(nextEventPoint, upperList, sweepline, eventQueue, status, out reportedIntersection);
if (reportedIntersection != null)
{
result.AddLast(reportedIntersection);
}
}
return(result);
}