internal void Remove(Event @event)
{
var index = _list.IndexOfValue(@event);
if (index != -1)
{
_list.RemoveAt(index);
}
}
public void Compute(HashSet<Point> points, int width, int height)
{
_root = null;
_width = width;
_height = height;
if (points.Count < 2)
{
return;
}
Edges = new List<Edge>();
Cells = new List<Cell>();
_queue = new Queue();
foreach (Point point in points)
{
var @event = new Event(point, true);
var cell = new Cell(point);
point.Cell = cell;
_queue.Enqueue(@event);
Cells.Add(cell);
}
while (!_queue.IsEmpty())
{
Event @event = _queue.Dequeue();
_ly = @event.Point.Y;
if (@event.IsParabola)
{
InsertParabola(@event.Point);
}
else
{
RemoveParabola(@event);
}
_lasty = @event.Point.Y;
}
FinishEdge(_root);
for (var i = 0; i < Edges.Count; i++)
{
if (Edges[i].Neighbour != null)
{
Edges[i].Start = Edges[i].Neighbour.End;
}
}
}
internal void Enqueue(Event @event)
{
_list.Add(@event.Point.Y, @event);
}
private void CheckCircle(Parabola b)
{
Parabola lp = GetLeftParent(b);
Parabola rp = GetRightParent(b);
Parabola a = GetLeftChild(lp);
Parabola c = GetRightChild(rp);
if (a == null || c == null || Equals(a.Site, c.Site)) return;
Point s = GetEdgeIntersection(lp.Edge, rp.Edge);
if (s == null) return;
double d = Distance(a.Site, s);
if (s.Y - d >= _ly) return;
var e = new Event(new Point(s.X, s.Y - d), false);
b.CircleEvent = e;
e.Arch = b;
_queue.Enqueue(e);
}
private void RemoveParabola(Event e)
{
Parabola p1 = e.Arch;
Parabola xl = GetLeftParent(p1);
Parabola xr = GetRightParent(p1);
Parabola p0 = GetLeftChild(xl);
Parabola p2 = GetRightChild(xr);
if (p0.CircleEvent != null)
{
_queue.Remove(p0.CircleEvent);
p0.CircleEvent = null;
}
if (p2.CircleEvent != null)
{
_queue.Remove(p2.CircleEvent);
p2.CircleEvent = null;
}
var p = new Point(e.Point.X, GetY(p1.Site, e.Point.X));
if (Equals(p0.Site.Cell.Last, p1.Site.Cell.First)) p1.Site.Cell.AddLeft(p);
else p1.Site.Cell.AddRight(p);
p0.Site.Cell.AddRight(p);
p2.Site.Cell.AddLeft(p);
_lasty = e.Point.Y;
xl.Edge.End = p;
xr.Edge.End = p;
Parabola higher = null;
Parabola par = p1;
while (par != _root)
{
par = par.Parent;
if (par == xl)
{
higher = xl;
}
if (par == xr)
{
higher = xr;
}
}
higher.Edge = new Edge(p, p0.Site, p2.Site);
Edges.Add(higher.Edge);
Parabola gparent = p1.Parent.Parent;
if (p1.Parent.Left == p1)
{
if (gparent.Left == p1.Parent) gparent.Left = p1.Parent.Right;
else p1.Parent.Parent.Right = p1.Parent.Right;
}
else
{
if (gparent.Left == p1.Parent) gparent.Left = p1.Parent.Left;
else gparent.Right = p1.Parent.Left;
}
CheckCircle(p0);
CheckCircle(p2);
}