public EventPoint(PointFr value, EventPointType type, LineSegmentFr?segment, SweepLine sweepLine)
{
PointValue = value;
Type = type;
Segment = segment;
SweepLine = sweepLine;
}
public EventPoint(PointFr value, EventPointType type, LineSegmentFr[] crossingSegments, SweepLine sweepLine)
{
PointValue = value;
Type = type;
CrossingSegments = crossingSegments;
SweepLine = sweepLine;
}
private readonly TreeDictionary <PointFr, C5.LinkedList <EventPoint> > _events; // Posortowana mapa punktów i odpowiadających im zdarzeń
public EventQueue(C5.HashSet <LineSegmentFr> segments, SweepLine sweepLine) // Tworzy nową kolejkę zdarzeń przy użyciu zestawu odcinków
{
if (segments.Count <= 0)
{
throw new ArgumentException($"Kolekcja {nameof(segments)} nie może być pusta");
}
_events = new TreeDictionary <PointFr, C5.LinkedList <EventPoint> >(new PointFrXThenYComparer());
var minY = Fraction.PositiveInfinity;
var maxY = Fraction.NegativeInfinity;
var minDeltaX = Fraction.PositiveInfinity;
var xs = new TreeSet <Fraction>();
foreach (var s in segments)
{
xs.Add(s.StartPoint.X);
xs.Add(s.EndPoint.X);
if (s.MinY < minY)
{
minY = s.MinY;
}
if (s.MaxY > maxY)
{
maxY = s.MaxY;
}
Insert(s.StartPoint, new EventPoint(s.StartPoint, EventPointType.Left, s, sweepLine));
Insert(s.EndPoint, new EventPoint(s.EndPoint, EventPointType.Right, s, sweepLine));
}
var xsArray = xs.ToArray();
for (var i = 1; i < xsArray.Length; i++)
{
var tempDeltaX = xsArray[i] - xsArray[i - 1];
if (tempDeltaX < minDeltaX)
{
minDeltaX = tempDeltaX;
}
}
var deltaY = maxY - minY;
var slope = deltaY / minDeltaX * -1; // * 1000
sweepLine.SweepLineValue = new LineFr(PointFr.Origin, new PointFr(0, 1)); // slope, PointFr.Origin
sweepLine.EventQueue = this; // Porzuciłem pomysł dynamicznego zmianu nachylenia miotły, ponieważ wymagało to obliczania dużych wartości przecięć z osiami wykresu dla prostej przy użyciu Ułamków (StackOverflowException)
}
public static Dictionary <PointFr, C5.HashSet <LineSegmentFr> > IntersectionsBentleyOttmann(C5.HashSet <LineSegmentFr> segments, out Dictionary <PointFr, LineFr> sweepLines)
{
if (segments.Count < 2)
{
sweepLines = null;
return(new Dictionary <PointFr, C5.HashSet <LineSegmentFr> >());
}
var sweepLine = new SweepLine();
var eventQueue = new EventQueue(segments, sweepLine);
while (!eventQueue.isEmpty())
{
var eventPoints = eventQueue.DeleteMin();
sweepLine.HandleEventPoints(eventPoints);
}
sweepLines = sweepLine.OldSweepLineValues;
return(sweepLine.Intersections);
}