private void ProcessOverlaps(int start, int end,
SweepLineEvent ev0, SegmentIntersector si)
{
MonotoneChain mc0 = (MonotoneChain)ev0.Object;
/// <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 ev1 = (SweepLineEvent)events[i];
if (ev1.IsInsert)
{
MonotoneChain mc1 = (MonotoneChain)ev1.Object;
// don't Compare edges in same group
// null group indicates that edges should be compared
if (ev0.EdgeSet == null || (ev0.EdgeSet != ev1.EdgeSet))
{
mc0.ComputeIntersections(mc1, si);
nOverlaps++;
}
}
}
}
/// <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();
for (int i = 0; i < events.Count; i++)
{
SweepLineEvent ev = (SweepLineEvent)events[i];
if (ev.IsDelete)
{
ev.InsertEvent.DeleteEventIndex = i;
}
}
}
private void ComputeIntersections(SegmentIntersector si)
{
nOverlaps = 0;
PrepareEvents();
for (int i = 0; i < events.Count; i++)
{
SweepLineEvent ev = (SweepLineEvent)events[i];
if (ev.IsInsert)
{
ProcessOverlaps(i, ev.DeleteEventIndex, ev, si);
}
}
}
public SweepLineEvent(object edgeSet, double x,
SweepLineEvent insertEvent, object obj)
{
this.edgeSet = edgeSet;
this.xValue = x;
this.insertEvent = insertEvent;
this.eventType = SweepLineEventType.INSERT;
if (insertEvent != null)
{
this.eventType = SweepLineEventType.DELETE;
}
this.obj = obj;
}
private void Add(Edge edge, object edgeSet)
{
ICoordinateList pts = edge.Coordinates;
for (int i = 0; i < pts.Count - 1; i++)
{
SweepLineSegment ss = new SweepLineSegment(edge, i);
SweepLineEvent insertEvent = new SweepLineEvent(edgeSet, ss.MinX, null, ss);
events.Add(insertEvent);
events.Add(new SweepLineEvent(edgeSet, ss.MaxX, insertEvent, ss));
}
}
private void Add(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), null, mc);
events.Add(insertEvent);
events.Add(new SweepLineEvent(edgeSet, mce.GetMaxX(i), insertEvent, mc));
}
}
/// <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);
}
private void ProcessOverlaps(int start, int end,
SweepLineEvent ev0, SegmentIntersector si)
{
SweepLineSegment ss0 = (SweepLineSegment)ev0.Object;
/// <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 ev1 = (SweepLineEvent)events[i];
if (ev1.IsInsert)
{
SweepLineSegment ss1 = (SweepLineSegment)ev1.Object;
if (ev0.EdgeSet == null || (ev0.EdgeSet != ev1.EdgeSet))
{
ss0.ComputeIntersections(ss1, si);
nOverlaps++;
}
}
}
}
