public static Polygon SolvePulleyProblem(Circle circle1, Circle circle2)
{
if (circle1.Radius < circle2.Radius)
Helper.Swap(ref circle1, ref circle2);
Debug.Assert(!circle1.Contains(circle2));
double edgeLength = (circle1.Center - circle2.Center).Length;
double cosAngle = (circle1.Radius - circle2.Radius) / edgeLength;
double angle = Math.Acos(cosAngle);
Debug.Assert(angle >= 0 && angle <= Math.PI / 2);
double lineAngle = Math.Atan2(circle2.Center.Y - circle1.Center.Y, circle2.Center.X - circle1.Center.X);
double cosPlusPlus = Math.Cos(lineAngle + angle);
double sinPlusPlus = Math.Sin(lineAngle + angle);
double cosPlusMinus = Math.Cos(lineAngle - angle);
double sinPlusMinus = Math.Sin(lineAngle - angle);
Vector line1Point1 = new Vector(
circle1.Center.X + circle1.Radius * cosPlusPlus,
circle1.Center.Y + circle1.Radius * sinPlusPlus);
Vector line2Point1 = new Vector(
circle1.Center.X + circle1.Radius * cosPlusMinus,
circle1.Center.Y + circle1.Radius * sinPlusMinus);
Vector line1Point2 = new Vector(
circle2.Center.X + circle2.Radius * cosPlusPlus,
circle2.Center.Y + circle2.Radius * sinPlusPlus);
Vector line2Point2 = new Vector(
circle2.Center.X + circle2.Radius * cosPlusMinus,
circle2.Center.Y + circle2.Radius * sinPlusMinus);
return Polygon.FromPoints(line1Point1, line1Point2, line2Point2, line2Point1);
}
public double DistanceToCircleArea(Circle circle)
{
return Math.Max((this - circle.Center).Length - circle.Radius, 0);
}
public bool Contains(Circle circle)
{
return circle.Radius <= this.Radius &&
(circle.Center - this.Center).LengthSquared <= MathHelper.Sqr(this.Radius - circle.Radius);
}