/// <summary>
/// Returns the corresponding circle's centre.
/// </summary>
public C2DPoint GetCircleCentre()
{
if (!IsValid())
{
return(new C2DPoint(0, 0));
}
C2DPoint MidPoint = new C2DPoint(Line.GetMidPoint());
double dMinToStart = MidPoint.Distance(Line.point);
double dMidToCentre = Math.Sqrt(Radius * Radius - dMinToStart * dMinToStart);
C2DVector MidToCentre = new C2DVector(Line.vector);
if (CentreOnRight)
{
MidToCentre.TurnRight();
}
else
{
MidToCentre.TurnLeft();
}
MidToCentre.SetLength(dMidToCentre);
return(MidPoint.GetPointTo(MidToCentre));
}
/// <summary>
/// True if this crosses the other and returns the intersectin points.
/// </summary>
/// <param name="Other">The other circle.</param>
/// <param name="IntersectionPts">The point set to recieve the result.</param>
public bool Crosses(C2DCircle Other, List <C2DPoint> IntersectionPts)
{
double x1 = _Centre.x;
double y1 = _Centre.y;
double R1 = Radius;
double x2 = Other.Centre.x;
double y2 = Other.Centre.y;
double R2 = Other.Radius;
double D = Other.Centre.Distance(_Centre);
if (D == 0)
{
return(false);
}
if (D == (R1 + R2))
{
C2DVector V = new C2DVector(_Centre, Other.Centre);
V.SetLength(R1);
C2DPoint P = new C2DPoint(_Centre.GetPointTo(V));
IntersectionPts.Add(P);
return(true);
}
if (D > (R1 + R2) || D < Math.Abs(R1 - R2))
{
return(false);
}
double A = (D + R1 + R2) * (D + R1 - R2) * (D - R1 + R2) * (-D + R1 + R2);
A = Math.Sqrt(A) / 4;
double XE1 = (x1 + x2) / 2 - (x1 - x2) * (R1 * R1 - R2 * R2) / (2 * D * D);
double XE2 = 2 * (y1 - y2) * A / (D * D);
double YE1 = (y1 + y2) / 2 - (y1 - y2) * (R1 * R1 - R2 * R2) / (2 * D * D);
double YE2 = 2 * (x1 - x2) * A / (D * D);
C2DPoint pt1 = new C2DPoint(XE1 + XE2, YE1 - YE2);
C2DPoint pt2 = new C2DPoint(XE1 - XE2, YE1 + YE2);
IntersectionPts.Add(pt1);
IntersectionPts.Add(pt2);
return(true);
}
/// <summary>
/// True if this crosses the other and returns the intersectin points.
/// </summary>
/// <param name="Other">The other circle.</param>
/// <param name="IntersectionPts">The point set to recieve the result.</param>
public bool Crosses(C2DCircle Other, List<C2DPoint> IntersectionPts)
{
double x1 = _Centre.x;
double y1 = _Centre.y;
double R1 = Radius;
double x2 = Other.Centre.x;
double y2 = Other.Centre.y;
double R2 = Other.Radius;
double D = Other.Centre.Distance(_Centre);
if (D == 0)
return false;
if (D == (R1 + R2) )
{
C2DVector V = new C2DVector(_Centre, Other.Centre);
V.SetLength(R1);
C2DPoint P = new C2DPoint(_Centre.GetPointTo( V ));
IntersectionPts.Add(P);
return true;
}
if ( D > (R1 + R2) || D < Math.Abs(R1 - R2))
return false;
double A = (D + R1 + R2) * (D + R1 - R2) * (D - R1 + R2) * (-D + R1 + R2);
A = Math.Sqrt(A) / 4;
double XE1 = (x1 + x2) / 2 - (x1 - x2) * (R1 * R1 - R2 * R2) / (2 * D * D);
double XE2 = 2 * (y1 - y2) * A / (D * D);
double YE1 = (y1 + y2) / 2 - (y1 - y2) * (R1 * R1 - R2 * R2) / (2 * D * D);
double YE2 = 2 * (x1 - x2) * A / (D * D);
C2DPoint pt1 = new C2DPoint( XE1 + XE2, YE1 - YE2);
C2DPoint pt2 = new C2DPoint( XE1 - XE2, YE1 + YE2);
IntersectionPts.Add(pt1);
IntersectionPts.Add(pt2);
return true;
}
/// <summary>
/// Returns the corresponding circle's centre.
/// </summary>
public C2DPoint GetCircleCentre()
{
if (!IsValid() )
return new C2DPoint(0, 0);
C2DPoint MidPoint = new C2DPoint(Line.GetMidPoint());
double dMinToStart = MidPoint.Distance( Line.point);
double dMidToCentre = Math.Sqrt( Radius * Radius - dMinToStart * dMinToStart);
C2DVector MidToCentre = new C2DVector(Line.vector);
if ( CentreOnRight)
MidToCentre.TurnRight();
else
MidToCentre.TurnLeft();
MidToCentre.SetLength(dMidToCentre);
return (MidPoint.GetPointTo(MidToCentre));
}