/// <summary>
/// Checking whether two rays intersect. Their intersection is center of a cirlcle.(circle event)
/// Using projection it checks if the event is on the correct place.
/// </summary>
/// <param name="par"></param>
private void checkCircle(Parabola par)
{
var leftSeg = par.GetLeftSegment();
var rightSeg = par.GetRightSegment();
if (leftSeg == null || rightSeg == null)
{
return;
}
var center = Segment.GetTwoLinesIntersection(leftSeg, rightSeg);
if (!center.HasValue)
{
return;
}
var c = center.Value;
Segment s = null;
if (center == leftSeg.Start)
{
s = rightSeg;
}
else
{
s = leftSeg;
}
var u = s.Start.Value - c;
if (u.Length() < NumericsUtils.Vector2Epsilon)
{
return;
}
var v = (u).Normalize() - s.Direction.Value.Normalize();
if (v.Length() < NumericsUtils.Vector2Epsilon /*&& center != sl.Start && center != sr.Start*/)
{
return;
}
var radius = (c - par.Site).Length();
if (c.Y - radius - directixY > NumericsUtils.Vector2Epsilon)
{
return;
}
if (par.CircleEvent != null)
{
par.CircleEvent.Invalidate();// when this happens the segment should be removed because it is invalid. maybe start = end => zero lenght
}
CircleEvent cev = new CircleEvent(c.X, c.Y, radius);
cev.Parabola = par;
par.CircleEvent = cev;
queue.Insert(cev);
}
/// <summary>
/// Reaction to the cirle event. Removes the parabola associated to this event.
/// It also rebuilds the tree.
/// </summary>
/// <param name="ce"></param>
private void removeParabola(CircleEvent ce)
{
var p = ce.Parabola;
var pl = p.GetLeftParent();
var pr = p.GetRightParent();
var l = p.GetLeafParabolaOnTheLeft();
var r = p.GetLeafParabolaOnTheRight();
var sl = pl.Segment;
var sr = pr.Segment;
if (l.CircleEvent != null)
{
l.CircleEvent.Invalidate();
}
if (r.CircleEvent != null)
{
r.CircleEvent.Invalidate();
}
if (sl != null)
{
sl.End = ce.Center;
}
if (sr != null)
{
sr.End = ce.Center;
}
var seg = new Segment(ce.Center.Value, r.Site, l.Site);
segs.Add(seg);
var pp = p.Parent;
if (pp.GetRightNode() == p)//removed parabole is on the right so the left one is correct
{
if (pp.Parent.GetLeftNode() == pp)
{
pp.Parent.SetLeftParabola(pp.GetLeftNode());
}
if (pp.Parent.GetRightNode() == pp)
{
pp.Parent.SetRightParabola(pp.GetLeftNode());
}
pr.Segment = seg;
}
else
{
if (pp.Parent.GetLeftNode() == pp)
{
pp.Parent.SetLeftParabola(pp.GetRightNode());
}
if (pp.Parent.GetRightNode() == pp)
{
pp.Parent.SetRightParabola(pp.GetRightNode());
}
pl.Segment = seg;
}
checkCircle(l);
checkCircle(r);
}