// This creates the VisibilityVertex objects along the segments.
internal VisibilityGraph Generate(IEnumerable <ScanSegment> hSegments, IEnumerable <ScanSegment> vSegments)
{
foreach (ScanSegment seg in vSegments)
{
eventList.Add(new SegEvent(SegEventType.VOpen, seg));
eventList.Add(new SegEvent(SegEventType.VClose, seg));
}
foreach (ScanSegment seg in hSegments)
{
eventList.Add(new SegEvent(SegEventType.HOpen, seg));
}
if (0 == eventList.Count)
{
return(null); // empty
}
eventList.Sort(this);
// Note: We don't need any sentinels in the scanline here, because the lowest VOpen
// events are loaded before the first HOpen is.
// Process all events.
visGraph = VisibilityGraphGenerator.NewVisibilityGraph();
foreach (SegEvent evt in eventList)
{
switch (evt.EventType)
{
case SegEventType.VOpen:
OnSegmentOpen(evt.Segment);
ScanInsert(evt.Segment);
break;
case SegEventType.VClose:
OnSegmentClose(evt.Segment);
ScanRemove(evt.Segment);
break;
case SegEventType.HOpen:
OnSegmentOpen(evt.Segment);
ScanIntersect(evt.Segment);
break;
default:
Debug.Assert(false, "Unknown SegEventType");
// ReSharper disable HeuristicUnreachableCode
break;
// ReSharper restore HeuristicUnreachableCode
}
} // endforeach
return(visGraph);
}
