/// <summary>
/// Shortest distance between two circles (including interior points) (approximate solution)
/// <para> The output points may be not unique in case of intersecting objects.</para>
/// </summary>
/// <param name="s">Target sphere</param>
/// <param name="p1">Closest point on circle</param>
/// <param name="p2">Closest point on sphere</param>
public double DistanceTo(Sphere s, out Point3d p1, out Point3d p2)
{
Plane3d p = this.ToPlane;
if (s.Center.ProjectionTo(p).BelongsTo(this))
{
p1 = s.Center.ProjectionTo(p);
if (s.Center == p1)
{
p2 = s.Center.Translate(s.R * this.Normal.Normalized);
}
else
{
p2 = s.Center.Translate(s.R * new Vector3d(s.Center, p1).Normalized);
}
return(s.DistanceTo(p));
}
if (this.Intersects(s))
{
Object obj = s.IntersectionWith(p);
if (obj.GetType() == typeof(Point3d))
{
p1 = (Point3d)obj;
p2 = p1;
}
else
{
Circle3d c = (Circle3d)obj;
p1 = this.Center.Translate(this.R * new Vector3d(this.Center, c.Center).Normalized);
p2 = c.Center.Translate(c.R * new Vector3d(c.Center, this.Center).Normalized);
}
return(0);
}
double dist = _distance_cicle_to_sphere(this, s, out p1, out p2);
return(dist);
}
/// <summary>
/// Intersection check between circle and sphere
/// </summary>
public bool Intersects(Sphere s)
{
if (this.Center.DistanceTo(s.Center) <= this.R + s.R)
{
Object obj = s.IntersectionWith(this.ToPlane);
if (obj != null && obj.GetType() == typeof(Circle3d))
{
// Check for circle-circle intersection
if (this.IntersectionWith((Circle3d)obj) != null)
{
return(true);
}
}
else if (obj != null && obj.GetType() == typeof(Point3d))
{
return(((Point3d)obj).BelongsTo(this));
}
else
{
return(false);
}
}
return(false);
}
/// <summary>
/// Get intersection of plane with sphere.
/// Returns 'null' (no intersection) or object of type 'Point3d' or 'Circle3d'.
/// </summary>
public object IntersectionWith(Sphere s)
{
return(s.IntersectionWith(this));
}
