Circle Class

From Kris Steele:

/// <summary> 
/// Represents a 2D circle. 
/// </summary> 
public struct Circle
{
    private Vector2 v;
    private Vector2 direction;
    private float distanceSquared;
 
    /// <summary> 
    /// Center position of the circle. 
    /// </summary> 
    public Vector2 Center;
 
    /// <summary> 
    /// Radius of the circle. 
    /// </summary> 
    public float Radius;
 
    /// <summary> 
    /// Constructs a new circle. 
    /// </summary> 
    public Circle(Vector2 position, float radius)
    {
        this.distanceSquared = 0f;
        this.direction = Vector2.Zero;
        this.v = Vector2.Zero;
        this.Center = position;
        this.Radius = radius;
    }
 
    /// <summary> 
    /// Determines if a circle intersects a rectangle. 
    /// </summary> 
    /// <returns>True if the circle and rectangle overlap. False otherwise.</returns> 
    public bool Intersects(Rectangle rectangle)
    {
        this.v = new Vector2(MathHelper.Clamp(Center.X, rectangle.Left, rectangle.Right),
                                MathHelper.Clamp(Center.Y, rectangle.Top, rectangle.Bottom));
 
        this.direction = Center - v;
        this.distanceSquared = direction.LengthSquared();
 
        return ((distanceSquared > 0) && (distanceSquared < Radius * Radius));
    }
}