make sprite NPC look at player

Assets/_PROJECT/Scripts/NPCController.cs

@@ -1,13 +1,13 @@
-using System.Collections;
-using System.Collections.Generic;
-using UnityEngine;
 using DG.Tweening;
+using Unity.XR.CoreUtils;
+using UnityEngine;
 
 public class NPCController : MonoBehaviour
 {
     private Vector3 mouthClosedScale;
     private Vector3 mouthOpenScale;
     private bool isTalking;
+    private Transform playerTransform;
 
     public Transform mouthTransform;
     public float mouthScalingMultiplier = 2.5f;
@@ -25,7 +25,40 @@ public class NPCController : MonoBehaviour
     // Update is called once per frame
     void Update()
     {
-        
+        if (playerTransform != null)
+        {
+            // As if player is on same Y coordinate as this object, to not rotate around Y axis.
+            Vector3 lookTargetPos = new Vector3(playerTransform.position.x, transform.position.y, playerTransform.position.z);
+            transform.LookAt(lookTargetPos);
+        }
+    }
+
+    private void OnTriggerEnter(Collider other)
+    {
+        Debug.Log("Collided with " + other);
+        KbmController controller = other.GetComponent<KbmController>();
+        XROrigin playerOrigin = other.GetComponent<XROrigin>();
+        if (controller != null)
+        {
+            playerTransform = controller.transform;
+        } else if (playerOrigin != null)
+        {
+            playerTransform = playerOrigin.transform;
+        }
+    }
+
+    private void OnTriggerExit(Collider other)
+    {
+        KbmController controller = other.GetComponent<KbmController>();
+        XROrigin playerOrigin = other.GetComponent<XROrigin>();
+        if (controller != null)
+        {
+            playerTransform = null;
+        }
+        else if (playerOrigin != null)
+        {
+            playerTransform = null;
+        }
     }
 
     public void StartTalking()