Xline is only one direction?

[joantopo]

Why, with xline (not a ray) I have to create two xline if I want to look for the intersecction (  GetIntersectionWith()  ) for both sides.?

For example, If I have a circle and I create a xline with BasePoint in the center, with  GetIntersectionWith() we will get only 1 cross point.

I know that we can do:

   xl.UnitDir = vector;

and

xl.UnitDir=vector.negate;

But it is the same that create 2 rays. So, what is the benefits of using xline?

Thanks in advance.

[joantopo]

Is not the same this?:

              
                Xline LineaAuxiliar = new Xline();
                //LineaAuxiliar.BasePoint = new Point3d(ptBase.X, ptBase.Y, 0);
                //LineaAuxiliar.SecondPoint = new Point3d(segundoPunto.X, segundoPunto.Y, 0);

 

than:

 Xline LineaAuxiliar = new Xline(); 
Vector3d vector = new Vector3d(segundoPunto.X - ptBase.X, segundoPunto.Y - ptBase.Y, 0);
 LineaAuxiliar.UnitDir = vector;

 I don´t get the same results.

[joantopo]

UnitDir is always from origin, isn´t it?

So, I have to use BasePoint and SecondPoint obligatory.

[joantopo · Accepted solution]

Sorry, I was wrong. 

I have fixed the length  to obtain Second point very far from BasePoint.