Camera to follow a target within a circle?

Hello Devs,

I am working on a script where the camera follows the player (only on 'y' axis). If the player moves in X or Z axis I would like the camera to follow only when the player moves beyonds a circle with a radius 'r' and the origin as camera's X & Z co-ordinates.

To brief it in another view, I would like to have camera's co-ordinates (X & Z) as origin and with a radius r, I want to create a imaginary circle. Lets say a gameobject is a target for the camera and the camera is following the target across Y axis. I would like the camera to follow the player, one and only if it moves beyond the CIRCLE.

I did try out but I got stuck at a certain point. The code is as follows,

 Vector2 DrawCircle(float originX, float originY, float r)
 {
 
  Vector2 cir;
     
  for (int i= 0; i < 180; i++)
     
  {

 

 Circle.x = r * Mathf.Cos(i*Mathf.DegToRad) + originX;
         Circle.y = r * Mathf.Sin(i*Mathf.DegToRad) + originY;
         cir = new Vector2(Circle.x, Circle.y);
  return cir;
     } 
 }

Please do help me, if you could. If you think any other solution, kindly let me know.

Thank you and Please,

Karsnen.