/// <summary>
///
/// </summary>
/// <param name="start"></param>
/// <param name="end"></param>
/// <param name="ev0"></param>
/// <param name="si"></param>
private void ProcessOverlaps(int start, int end, SweepLineEvent ev0, SegmentIntersector si)
{
SweepLineSegment ss0 = (SweepLineSegment)ev0.Object;
/*
* 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.
*/
for (int i = start; i < end; i++)
{
SweepLineEvent ev1 = _events[i];
if (ev1.IsInsert)
{
SweepLineSegment ss1 = (SweepLineSegment)ev1.Object;
// don't compare edges in same group, if labels are present
if (!ev0.IsSameLabel(ev1))
{
{
ss0.ComputeIntersections(ss1, si);
_nOverlaps++;
}
}
}
}
}
public bool IsSameLabel(SweepLineEvent ev)
{
// no label set indicates single group
if (_label == null)
{
return(false);
}
return(_label == ev._label);
}
/// <summary>
///
/// </summary>
/// <param name="edge"></param>
/// <param name="edgeSet"></param>
private void Add(Edge edge, object edgeSet)
{
Coordinate[] pts = edge.Coordinates;
for (int i = 0; i < pts.Length - 1; i++)
{
SweepLineSegment ss = new SweepLineSegment(edge, i);
SweepLineEvent insertEvent = new SweepLineEvent(edgeSet, ss.MinX, null);
_events.Add(insertEvent);
_events.Add(new SweepLineEvent(ss.MaxX, insertEvent));
}
}
/// <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 PrepareEvents()
{
_events.Sort();
// set DELETE event indexes
for (int i = 0; i < _events.Count; i++)
{
SweepLineEvent ev = _events[i];
if (ev.IsDelete)
{
ev.InsertEvent.DeleteEventIndex = i;
}
}
}
/// <summary>
///
/// </summary>
/// <param name="edge"></param>
/// <param name="edgeSet"></param>
private void AddEdge(Edge edge, object edgeSet)
{
MonotoneChainEdge mce = edge.MonotoneChainEdge;
int[] startIndex = mce.StartIndexes;
for (int i = 0; i < startIndex.Length - 1; i++)
{
MonotoneChain mc = new MonotoneChain(mce, i);
SweepLineEvent insertEvent = new SweepLineEvent(edgeSet, mce.GetMinX(i), mc);
_events.Add(insertEvent);
_events.Add(new SweepLineEvent(mce.GetMaxX(i), insertEvent));
}
}
/// <summary>
///
/// </summary>
/// <param name="si"></param>
private void ComputeIntersections(SegmentIntersector si)
{
_nOverlaps = 0;
PrepareEvents();
for (int i = 0; i < _events.Count; i++)
{
SweepLineEvent ev = _events[i];
if (ev.IsInsert)
{
ProcessOverlaps(i, ev.DeleteEventIndex, ev, si);
}
}
}
/// <summary>
///
/// </summary>
/// <param name="si"></param>
private void ComputeIntersections(SegmentIntersector si)
{
_nOverlaps = 0;
PrepareEvents();
for (int i = 0; i < _events.Count; i++)
{
SweepLineEvent ev = _events[i];
if (ev.IsInsert)
{
// Console.WriteLine("Processing event " + i);
ProcessOverlaps(i, ev.DeleteEventIndex, ev, si);
}
if (si.IsDone)
{
break;
}
}
}
/// <summary>
/// Events are ordered first by their x-value, and then by their eventType.
/// 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>
/// <param name="o"></param>
public int CompareTo(object o)
{
SweepLineEvent pe = (SweepLineEvent)o;
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);
}
/// <summary>
/// Creates a DELETE event.
/// </summary>
/// <param name="x">The event location</param>
/// <param name="insertEvent">The corresponding INSERT event</param>
public SweepLineEvent(double x, SweepLineEvent insertEvent)
{
_eventType = Delete;
_xValue = x;
_insertEvent = insertEvent;
}
