private FortuneEvent getCircleEvent(FortuneArc arc1,
FortuneArc arc2,
FortuneArc arc3,
double y)
{
ICoordinate a = arc1.Site.Cell.DataPoint;
ICoordinate b = arc2.Site.Cell.DataPoint;
ICoordinate c = arc3.Site.Cell.DataPoint;
//bc should turn to the right with respect to ab
if ((b.X - a.X) * (c.Y - a.Y) - (c.X - a.X) * (b.Y - a.Y) > 0)
{
return(null);
}
ICoordinate point = getCircleCenter(a, b, c);
if (point != null)
{
FortuneCircleEvent newEvent = new FortuneCircleEvent();
newEvent.CircleCenter = point;
double distance = PlanimetryAlgorithms.Distance(point, a);
point = PlanimetryEnvironment.NewCoordinate(point.X, point.Y - distance);
newEvent.Point = point;
newEvent.Arc = arc2;
if (_buildTriangles)
{
newEvent.Triangle = new Triangle(arc1.Site.Cell, arc2.Site.Cell, arc3.Site.Cell);
}
return(newEvent);
}
return(null);
}
private void handleCircleEvent(FortuneCircleEvent ev)
{
FortuneArc ln = ev.Arc.LeftNeighbor;
FortuneArc rn = ev.Arc.RightNeighbor;
// remove events range associated with this arc
if (ln.CircleEvent != null)
{
_eventList.Remove(ln.CircleEvent);
}
if (rn.CircleEvent != null)
{
_eventList.Remove(rn.CircleEvent);
}
// remove the arc of coastline
_shoreLine.RemoveArc(ev.Arc);
//fix slave nodes arc ribs
if (ev.Arc.LeftNode != null)
{
ev.Arc.LeftNode.Point = ev.CircleCenter;
ev.Arc.LeftNode.IsInfinit = false;
}
if (ev.Arc.RightNode != null)
{
ev.Arc.RightNode.Point = ev.CircleCenter;
ev.Arc.RightNode.IsInfinit = false;
}
// add a new edge
VoronoiEdge edge = new VoronoiEdge(ln.Site.Cell, rn.Site.Cell);
edge.Node1 = new VoronoiNode(ev.CircleCenter.X, ev.CircleCenter.Y);
edge.Node2 = new VoronoiNode((ln.Site.Cell.DataPoint.X + rn.Site.Cell.DataPoint.X) / 2,
(ln.Site.Cell.DataPoint.Y + rn.Site.Cell.DataPoint.Y) / 2);
//expand the bounding rectangle of the chart
_rectangle.Join(ev.CircleCenter);
// one node of the new edge is fixed, the second - no
edge.Node1.IsInfinit = false;
edge.Node2.IsInfinit = true;
// dobavleyaem edge to cells
ln.Site.Cell.AddEdge(edge);
rn.Site.Cell.AddEdge(edge);
//add a triangle in the Delaunay triangulation, if necessary
if (_buildTriangles)
{
_triangles.Add(ev.Triangle);
}
// not a fixed node is a new edge now vanished neighbors arc
ln.RightNode = edge.Node2;
rn.LeftNode = edge.Node2;
FortuneArc lnln = ln.LeftNeighbor;
FortuneArc lnrn = ln.RightNeighbor;
FortuneArc rnln = rn.LeftNeighbor;
FortuneArc rnrn = rn.RightNeighbor;
// add events to the newly formed circle arcs triples
if (lnln != null)
{
if (lnrn != null)
{
FortuneEvent eventToAdd = getCircleEvent(lnln, ln, lnrn, ev.Point.Y);
if (eventToAdd != null)
{
addCircleEvent(eventToAdd);
}
ln.CircleEvent = eventToAdd;
}
}
if (rnln != null)
{
if (rnrn != null)
{
FortuneEvent eventToAdd = getCircleEvent(rnln, rn, rnrn, ev.Point.Y);
if (eventToAdd != null)
{
addCircleEvent(eventToAdd);
}
rn.CircleEvent = eventToAdd;
}
}
}