Strange behaviour with WorldToScreenPoint

Question

Hello, I am trying to make an off-screen target indicator (COD revive style) with WorldToScreenPoint, it works as expected on the orthographic camera, but in perspective it behaves strangely when z position is negative. Any suggestion is appreciated. Video of the behaviour.

 using UnityEngine;
 
 public class ReviveIndicator : MonoBehaviour
 {
     public RectTransform indicator;
     public Transform target;
 
     Camera mainCamera;
 
     void Start()
     {
         mainCamera = Camera.main;
     }
 
     void Update()
     {
         Vector3 pos = mainCamera.WorldToScreenPoint(target.position);
  
         if(pos.z < 0)
         {
             pos *= -1;
         }
 
         pos.x = Mathf.Clamp(pos.x, 0, Screen.width);
         pos.y = Mathf.Clamp(pos.y, 0, Screen.height);
 
         indicator.position = pos;
     }
 }

Answer 1

I got it.

 using UnityEngine;
 
 public class ReviveIndicator : MonoBehaviour
 {
     [Header("References")]
     public RectTransform indicator;
     public Transform target;
     
     Transform canvas;
 
     Camera mainCamera;
 
     [Header("Variables")]
     public Vector3 offset;
 
     Vector3 screenCentre;
 
     void Start()
     {
         canvas = UIReferences.instance.transform;
         mainCamera = Camera.main;
     }
 
     void Update()
     {
         Vector3 screenPosition = mainCamera.WorldToScreenPoint(target.position);
 
         if (IsTargetVisible(screenPosition))
         {
             Vector3 pos = mainCamera.WorldToScreenPoint(target.position + offset);
 
             indicator.position = Vector3.MoveTowards(indicator.position, pos, 500 * Time.deltaTime);
 
             return;
         }
 
         screenCentre = new Vector3(Screen.width, Screen.height, 0) / 2;
 
         screenPosition -= screenCentre;
 
         if (screenPosition.z < 0)
         {
             screenPosition *= -1;
         }
 
         float angle = Mathf.Atan2(screenPosition.y, screenPosition.x);
         float slope = Mathf.Tan(angle);
 
         if (screenPosition.x > 0)
         {
             screenPosition = new Vector3(screenCentre.x, screenCentre.x * slope, 0);
         }
         else
         {
             screenPosition = new Vector3(-screenCentre.x, -screenCentre.x * slope, 0);
         }
 
         if (screenPosition.y > screenCentre.y)
         {
             screenPosition = new Vector3(screenCentre.y / slope, screenCentre.y, 0);
         }
         else if (screenPosition.y < -screenCentre.y)
         {
             screenPosition = new Vector3(-screenCentre.y / slope, -screenCentre.y, 0);
         }      
 
         screenPosition += screenCentre;
 
         float x = indicator.rect.width * canvas.localScale.x / 2;
         float y = indicator.rect.height * canvas.localScale.y / 2;
 
         screenPosition.x = Mathf.Clamp(screenPosition.x, x, Screen.width - x);
         screenPosition.y = Mathf.Clamp(screenPosition.y, y, Screen.height - y);
 
         indicator.position = Vector3.MoveTowards(indicator.position, screenPosition, 500 * Time.deltaTime);
     }
 
     bool IsTargetVisible(Vector3 screenPosition)
     {
         if(Player.instance != null)
         {
             if (Vector3.Distance(target.position, Player.instance.transform.position) >= 14)
             {
                 return false;
             }
         }
 
         bool isTargetVisible = screenPosition.z > 0 && screenPosition.x > 0 && screenPosition.x < Screen.width && screenPosition.y > 0 && screenPosition.y < Screen.height;
         return isTargetVisible;
     }
 }

Strange behaviour with WorldToScreenPoint

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