private void checkIntersection(Event upper,Event lower, OrderedSet<Event> Q,List<Point> outPoints)
{
Line a = new Line(upper.point,segments[upper.segIdx].End);
Line b = new Line(lower.point,segments[lower.segIdx].End);
if (HelperMethods.CheckTurn(new Line(a.Start, a.End), b.Start) == HelperMethods.CheckTurn(new Line(a.Start, a.End), b.End)
|| (HelperMethods.CheckTurn(new Line(b.Start, b.End), a.Start) == HelperMethods.CheckTurn(new Line(b.Start, b.End), a.End)))
return;
double aa, bb, cc, dd;
Point interPoint;
if (Math.Abs(a.Start.X - a.End.X) < Constants.Epsilon)
{
bb = (b.Start.Y - b.End.Y) / (b.Start.X - b.End.X);
dd = b.Start.Y - b.Start.X * bb;
interPoint = new Point(a.Start.X, (bb * a.Start.X + dd));
}
else if (Math.Abs(b.Start.X - b.End.X) < Constants.Epsilon)
{
aa = (a.Start.Y - a.End.Y) / (a.Start.X - a.End.X);
cc = a.Start.Y - a.Start.X * aa;
interPoint = new Point(b.Start.X, (aa * a.Start.X + cc));
}
else
{
aa = (a.Start.Y - a.End.Y) / (a.Start.X - a.End.X);
bb = (b.Start.Y - b.End.Y) / (b.Start.X - b.End.X);
cc = a.Start.Y - a.Start.X * aa;
dd = b.Start.Y - b.Start.X * bb;
double interX = (dd - cc) / (aa - bb);
interPoint = new Point(interX, (aa * interX + cc));
}
Q.Add(new Event(interPoint, PointType.Intersection,-1 ,upper,lower));
outPoints.Add(interPoint);
}
public Event(Point p, PointType type, int sIdx,Event _upper,Event _lower)
{
point = p; pType = type; segIdx = sIdx; upper = _upper; lower = _lower;
}
private double lineVal(Event line, double x)
{
Line a= segments[line.segIdx];
if(Math.Abs(a.Start.X-a.End.X)<Constants.Epsilon)
return double.MaxValue;
double m = (a.End.Y - a.Start.Y)/ (a.End.X - a.Start.X);
double c = a.Start.Y - (a.Start.X * m);
return x * m + c;
}
private void handleEvent(Event curEvent, OrderedSet<Event> L, OrderedSet<Event> Q, List<Point> outPoints)
{
switch (curEvent.pType)
{
case PointType.Start:
{
KeyValuePair<Event, Event> upLow = L.DirectUpperAndLower(curEvent);
if (upLow.Key != null)
checkIntersection(upLow.Key, curEvent, Q, outPoints);
if (upLow.Value != null)
checkIntersection(curEvent, upLow.Value, Q, outPoints);
L.Add(curEvent);
break;
}
case PointType.End:
{
KeyValuePair<Event, Event> upLow = L.DirectUpperAndLower(curEvent);
if (upLow.Key != null && upLow.Value != null)
checkIntersection(upLow.Key, upLow.Value, Q, outPoints);
L.Remove(new Event(segments[curEvent.segIdx].Start, PointType.Start, curEvent.segIdx, null, null));
break;
}
case PointType.Intersection:
{
Event upup = L.DirectUpperAndLower(curEvent.upper).Key;
Event lowlow = L.DirectUpperAndLower(curEvent.lower).Value;
if (upup !=null)
checkIntersection(upup, curEvent.lower, Q, outPoints);
if (lowlow != null)
checkIntersection(curEvent.upper,lowlow, Q, outPoints);
L.Remove(curEvent.upper); L.Remove(curEvent.lower);
curEvent.lower.point.X = curEvent.point.X;curEvent.lower.point.Y = curEvent.point.Y;
curEvent.upper.point.X = curEvent.point.X; curEvent.upper.point.Y = curEvent.point.Y;
L.Add(curEvent.upper); L.Add(curEvent.lower);
break;
}
default:
break;
}
}
private int comparerEventY(Event x, Event y)
{
if (x.pType == PointType.Start && y.pType == PointType.Start
&& x.segIdx == y.segIdx)
return 0;
if (x.point.Equals(y.point))
{
if(segments[x.segIdx].End.Equals(segments[y.segIdx].End))
return 0;
double maxEX = Math.Max(segments[x.segIdx].End.X, segments[y.segIdx].End.X);
return lineVal(x, maxEX) < lineVal(y, maxEX) ? -1 : 1;
}
double maxSX = Math.Max(x.point.X, y.point.X);
return lineVal(x, maxSX) < lineVal(y, maxSX) ? -1 : 1;
}
private int comparerEventX(Event x, Event y)
{
if (x.pType == PointType.Start && y.pType == PointType.Start
&& x.segIdx == y.segIdx)
return 0;
if (x.point.Equals(y.point))
return 0;
if (Math.Abs(x.point.X - y.point.X) < Constants.Epsilon)
return x.point.Y < y.point.Y ? -1 : 1;
return x.point.X < y.point.X ? -1 : 1;
}
