/// <summary>
/// Checks for intersection between two circles.
/// </summary>
/// <param name="a">The first circle.</param>
/// <param name="b">The second circle.</param>
/// <returns>True if the two specified circles intersect or if one is entirely contained in the other. False otherwise.</returns>
public static bool Intersects(ICircle2D a, ICircle2D b)
{
float centerDistanceSquared = (a.Center - b.Center).LengthSquared();
float radiusSum = a.Radius + b.Radius;
return(centerDistanceSquared <= radiusSum * radiusSum);
}
public bool Intersects(ICircle2D other)
{
float centerDistance = (_center - other.Center).Length();
float radiusSum = _radius + other.Radius;
return(centerDistance <= radiusSum);
}
/// <summary>
/// Finds the closest on the on specified circle.
/// </summary>
/// <param name="point">The point to which we want to find the closest point on the circle.</param>
/// <param name="circle">The circle on which to find the closest point.</param>
/// <returns>The point on the circle that is closest to the specified point.</returns>
public static Vector2 FindClosestPointOnCircle(Vector2 point, ICircle2D circle)
{
Vector2 vector = point - circle.Center;
vector.Normalize();
vector *= circle.Radius;
return(circle.Center + vector);
}
/// <summary>
/// Checks for intersection between a polygon and a circle.
/// </summary>
/// <param name="polygon">The circle.</param>
/// <param name="circle">The polygon.</param>
/// <returns>True if the two shapes intersect. False othwerise.</returns>
public static bool Intersects(IPolygon2D polygon, ICircle2D circle)
{
// See if the closest point of each edge to the circle's center is inside the center
Vector2 circleCenter = circle.Center;
for (int i = 0; i < polygon.NumSides; i++)
{
Vector2 closestPointOfEdge =
(i == polygon.NumSides - 1 ?
ShapeUtility.CalculateClosestPointOnEdge(circleCenter, polygon.Vertices[i], polygon.Vertices[0]) :
ShapeUtility.CalculateClosestPointOnEdge(circleCenter, polygon.Vertices[i], polygon.Vertices[i + 1]));
if (circle.Contains(closestPointOfEdge))
{
return(true);
}
}
// See if this polygon contains the other circle
if (polygon.Contains(circle.Center))
{
return(true);
}
return(false);
}
public bool Intersects(ICircle2D other)
{
return(ShapeUtility.Intersects(this, other));
}
/// <summary>
/// Checks to see if the specified point is contained in the specified circle.
/// </summary>
/// <param name="point">The point to check containment for.</param>
/// <param name="circle">The circle to check if the point lies within.</param>
/// <returns>True if the specified point is within the circle. False otherwise.</returns>
public static bool ContainsForCircle(Vector2 point, ICircle2D circle)
{
float centerDistanceSquared = (circle.Center - point).LengthSquared();
return(centerDistanceSquared <= circle.Radius * circle.Radius);
}
public override bool Intersects(ICircle2D other)
{
return(ShapeUtility.Intersects(other, this));
}
public static void DrawCircle(this SpriteBatch spriteBatch, ICircle2D circle, Color color, Matrix transformFromWorldToCamera)
{
DrawCircle(spriteBatch, circle.Center, circle.Radius, color, transformFromWorldToCamera);
}
public static void DrawCircle(this SpriteBatch spriteBatch, ICircle2D circle, Color color)
{
DrawCircle(spriteBatch, circle.Center, circle.Radius, color, Matrix.Identity);
}
public abstract bool Intersects(ICircle2D other);
public bool Intersects(ICircle2D other)
{
return(_polygon.Intersects(other));
}