public static MLine IntersectLine(MCircle c1, MCircle c2)
{
MPoint[] points = new MPoint[2];
points[0] = new MPoint(Double.NaN, Double.NaN);
points[1] = new MPoint(Double.NaN, Double.NaN);
double d = MPoint.Distance(c1.Center, c2.Center);
if (d > c1.Radius + c2.Radius)
{
return(null);
}
if (d < Math.Abs(c1.Radius - c2.Radius))
{
return(null);
}
if (Math.Abs(d) < Double.Epsilon && Math.Abs(c1.Radius - c2.Radius) < Double.Epsilon)
{
return(null);
}
double a = (c1.Radius * c1.Radius - c2.Radius * c2.Radius + d * d) / 2 * d;
double h = Math.Sqrt(c1.Radius * c1.Radius - a * a);
MPoint p2 = c1.Center + (c1.Center - c2.Center) * a / d;
points[0] = new MPoint(p2.X + h * (c2.Center.Y - c1.Center.Y) / d, p2.Y - h * (c2.Center.X - c1.Center.X) / d);
points[1] = new MPoint(p2.X - h * (c2.Center.Y - c1.Center.Y) / d, p2.Y + h * (c2.Center.X - c1.Center.X) / d);
return(new MLine(points[0], points[1]));
}
public static MPoint IntersectThree(MCircle c1, MCircle c2, MCircle c3)
{
MPoint[] points = IntersectPoints(c1, c2);
if (c3.onCircle(points[0]))
{
return(points[0]);
}
if (c3.onCircle(points[1]))
{
return(points[1]);
}
MLine[] lines = new MLine[2];
lines[0] = IntersectLine(c1, c2);
lines[1] = IntersectLine(c2, c3);
return(MLine.Intersect(lines[0], lines[1]));
}