public void Add(SweepLineInterval sweepInt)
{
SweepLineEvent insertEvent = new SweepLineEvent(sweepInt.Min, null, sweepInt);
events.Add(insertEvent);
events.Add(new SweepLineEvent(sweepInt.Max, insertEvent, sweepInt));
}
public SweepLineEvent(double x, SweepLineEvent insertEvent, SweepLineInterval sweepInt)
{
this.xValue = x;
this.insertEvent = insertEvent;
this.eventType = SweepLineEventType.INSERT;
if (insertEvent != null)
{
this.eventType = SweepLineEventType.DELETE;
}
this.sweepInt = sweepInt;
}
public void ComputeOverlaps(ISweepLineOverlapAction action)
{
nOverlaps = 0;
BuildIndex();
for (int i = 0; i < events.Count; i++)
{
SweepLineEvent ev = (SweepLineEvent)events[i];
if (ev.IsInsert)
{
ProcessOverlaps(i, ev.DeleteEventIndex, ev.Interval, action);
}
}
}
/// <summary> Because Delete Events have a link to their corresponding Insert event,
/// it is possible to compute exactly the range of events which must be
/// compared to a given Insert event object.
/// </summary>
private void BuildIndex()
{
if (indexBuilt)
{
return;
}
events.Sort();
for (int i = 0; i < events.Count; i++)
{
SweepLineEvent ev = (SweepLineEvent)events[i];
if (ev.IsDelete)
{
ev.InsertEvent.DeleteEventIndex = i;
}
}
indexBuilt = true;
}
private void ProcessOverlaps(int start, int end,
SweepLineInterval s0, ISweepLineOverlapAction action)
{
/// <summary> Since we might need to test for self-intersections,
/// include current insert event object in list of event objects to test.
/// Last index can be skipped, because it must be a Delete event.
/// </summary>
for (int i = start; i < end; i++)
{
SweepLineEvent ev = (SweepLineEvent)events[i];
if (ev.IsInsert)
{
SweepLineInterval s1 = ev.Interval;
action.Overlap(s0, s1);
nOverlaps++;
}
}
}
/// <summary>
/// ProjectionEvents are ordered first by their x-value, and then by their eventType.
/// It is important that Insert events are sorted before Delete events, so that
/// items whose Insert and Delete events occur at the same x-value will be
/// correctly handled.
/// </summary>
public int CompareTo(SweepLineEvent pe)
{
if (xValue < pe.xValue)
{
return(-1);
}
if (xValue > pe.xValue)
{
return(1);
}
if (eventType < pe.eventType)
{
return(-1);
}
if (eventType > pe.eventType)
{
return(1);
}
return(0);
}
