public double GetXOfEdge(VoronoiParabola par, double y)
{
VoronoiParabola left = VoronoiParabola.GetLeftChild(par);
VoronoiParabola right = VoronoiParabola.GetRightChild(par);
Vector2 p = left.Site;
Vector2 r = right.Site;
double dp = 2.0 * (p.Y - y);
double a1 = 1.0 / dp;
double b1 = -2.0 * p.X / dp;
double c1 = y + dp / 4 + p.X * p.X / dp;
dp = 2.0 * (r.Y - y);
double a2 = 1.0 / dp;
double b2 = -2.0 * r.X / dp;
double c2 = ly + dp / 4 + r.X * r.X / dp;
double a = a1 - a2;
double b = b1 - b2;
double c = c1 - c2;
double disc = b * b - 4 * a * c;
double x1 = (-b + Math.Sqrt(disc)) / (2 * a);
double x2 = (-b - Math.Sqrt(disc)) / (2 * a);
double ry;
if (p.Y < r.Y)
{
ry = Math.Max(x1, x2);
}
else
{
ry = Math.Min(x1, x2);
}
return(ry);
}
public void CheckCircle(VoronoiParabola b)
{
VoronoiParabola lp = VoronoiParabola.GetLeftParent(b);
VoronoiParabola rp = VoronoiParabola.GetRightParent(b);
VoronoiParabola a = VoronoiParabola.GetLeftChild(lp);
VoronoiParabola c = VoronoiParabola.GetRightChild(rp);
if (a == null || c == null || a.Site == c.Site)
{
return;
}
Vector2 s = Vector2.Zero;
s = GetEdgeIntersection(lp.Edge, rp.Edge);
if (s == Vector2.Zero)
{
return;
}
double dx = a.Site.X - s.X;
double dy = a.Site.Y - s.Y;
double d = Math.Sqrt((dx * dx) + (dy * dy));
if (s.Y - d >= ly)
{
return;
}
VoronoiEvent e = new VoronoiEvent(new Vector2(s.X, s.Y - (float)d), false);
points.Add(e.Position);
b.CEvent = e;
e.Arch = b;
queue.Enqueue(e);
}
public void RemoveParabola(VoronoiEvent e)
{
VoronoiParabola p1 = e.Arch;
VoronoiParabola xl = VoronoiParabola.GetLeftParent(p1);
VoronoiParabola xr = VoronoiParabola.GetRightParent(p1);
VoronoiParabola p0 = VoronoiParabola.GetLeftChild(xl);
VoronoiParabola p2 = VoronoiParabola.GetRightChild(xr);
if (p0.CEvent != null)
{
deleted.Add(p0.CEvent); p0.CEvent = null;
}
if (p2.CEvent != null)
{
deleted.Add(p2.CEvent); p2.CEvent = null;
}
Vector2 p = new Vector2(e.Position.X, (float)GetY(p1.Site, e.Position.X));
points.Add(p);
xl.Edge.End = p;
xr.Edge.End = p;
VoronoiParabola higher = null;
VoronoiParabola par = p1;
while (par != root)
{
par = par.Parent;
if (par == xl)
{
higher = xl;
}
if (par == xr)
{
higher = xr;
}
}
higher.Edge = new VoronoiEdge(p, p0.Site, p2.Site);
Edges.Add(higher.Edge);
VoronoiParabola gparent = p1.Parent.Parent;
if (p1.Parent.Left == p1)
{
if (gparent.Left == p1.Parent)
{
gparent.Left = p1.Parent.Right;
}
if (gparent.Right == p1.Parent)
{
gparent.Right = p1.Parent.Right;
}
}
else
{
if (gparent.Left == p1.Parent)
{
gparent.Left = p1.Parent.Left;
}
if (gparent.Right == p1.Parent)
{
gparent.Right = p1.Parent.Left;
}
}
CheckCircle(p0);
CheckCircle(p2);
}