public static void AddBeach(ref Dictionary <int, Cell> cells, ref RedBlackTree circles, ref RedBlackTree beaches, ref List <Edge> edges, Point site)
{
var x = site.X;
var directrix = site.Y;
RedBlackTree lArc = null;
RedBlackTree rArc = null;
var dxl = 0d;
var dxr = 0d;
var node = beaches._;
while (node != null)
{
dxl = LeftBreakPoint(node, directrix) - x;
if (dxl > Diagram.Epsilon)
{
node = node.L;
}
else
{
dxr = x - RightBreakPoint(node, directrix);
if (dxr > Diagram.Epsilon)
{
if (node.R == null)
{
lArc = node;
break;
}
node = node.R;
}
else
{
if (dxl > -Diagram.Epsilon)
{
lArc = node.P;
rArc = node;
}
else if (dxr > -Diagram.Epsilon)
{
lArc = node;
rArc = node.N;
}
else
{
lArc = rArc = node;
}
break;
}
}
}
Cell.CreateCell(ref cells, site);
var newArc = CreateBeach(site);
beaches.Insert(lArc, newArc);
if (lArc == null && rArc == null)
{
return;
}
if (lArc == rArc)
{
Circle.DetachCircle(ref circles, lArc);
rArc = CreateBeach(lArc.Site);
beaches.Insert(newArc, rArc);
newArc.Edge = rArc.Edge = Edge.CreateEdge(ref cells, ref edges, lArc.Site, newArc.Site);
Circle.AttachCircle(ref circles, lArc);
Circle.AttachCircle(ref circles, rArc);
return;
}
if (rArc == null)
{ // && lArc
newArc.Edge = Edge.CreateEdge(ref cells, ref edges, lArc.Site, newArc.Site);
return;
}
// else lArc !== rArc
Circle.DetachCircle(ref circles, lArc);
Circle.DetachCircle(ref circles, rArc);
var lSite = lArc.Site;
var ax = lSite.X;
var ay = lSite.Y;
var bx = site.X - ax;
var by = site.Y - ay;
var rSite = rArc.Site;
var cx = rSite.X - ax;
var cy = rSite.Y - ay;
var d = 2 * (bx * cy - by * cx);
var hb = bx * bx + by * by;
var hc = cx * cx + cy * cy;
var vertex = new Point((cy * hb - by * hc) / d + ax, (bx * hc - cx * hb) / d + ay);
rArc.Edge = Edge.SetEdgeEnd(rArc.Edge, lSite, rSite, vertex);
newArc.Edge = Edge.CreateEdge(ref cells, ref edges, lSite, site, null, vertex);
rArc.Edge = Edge.CreateEdge(ref cells, ref edges, site, rSite, null, vertex);
Circle.AttachCircle(ref circles, lArc);
Circle.AttachCircle(ref circles, rArc);
}
public static void AttachCircle(ref RedBlackTree circles, RedBlackTree arc)
{
var lArc = arc.P;
var rArc = arc.N;
if (lArc == null || rArc == null)
{
return;
}
var lSite = lArc.Site;
var cSite = arc.Site;
var rSite = rArc.Site;
if (lSite == rSite)
{
return;
}
var bx = cSite.X;
var by = cSite.Y;
var ax = lSite.X - bx;
var ay = lSite.Y - by;
var cx = rSite.X - bx;
var cy = rSite.Y - by;
var d = 2 * (ax * cy - ay * cx);
if (d >= -Diagram.Epsilon2)
{
return;
}
var ha = ax * ax + ay * ay;
var hc = cx * cx + cy * cy;
var x = (cy * ha - ay * hc) / d;
var y = (ax * hc - cx * ha) / d;
RedBlackTree circle = null;
if (Circle.CirclePool.Any())
{
circle = Circle.CirclePool.Last();
Circle.CirclePool.Remove(circle);
}
else
{
circle = new RedBlackTree();
}
circle.Arc = arc;
circle.Site = cSite;
circle.X = x + bx;
circle.Y = (circle.CY = y + by) + Math.Sqrt(x * x + y * y); // y bottom
arc.Circle = circle;
RedBlackTree before = null;
var node = circles._;
while (node != null)
{
if (circle.Y < node.Y || (circle.Y == node.Y && circle.X <= node.X))
{
if (node.L != null)
{
node = node.L;
}
else
{
before = node.P; break;
}
}
else
{
if (node.R != null)
{
node = node.R;
}
else
{
before = node; break;
}
}
}
circles.Insert(before, circle);
if (before == null)
{
FirstCircle = circle;
}
}