DeltaVR3DModelGeneration/Assets/_PROJECT/Scripts/NPCController.cs

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;
    public float mouthMovementDuration = 0.25f;

    // Start is called before the first frame update
    void Awake()
    {
        mouthClosedScale = mouthTransform.localScale;
        mouthOpenScale = new Vector3(mouthClosedScale.x, mouthClosedScale.y * mouthScalingMultiplier, mouthClosedScale.z);

        isTalking = false;
    }

    // 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()
    {
        isTalking = true;
        MoveMouth();
    }

    public void Stoptalking()
    {
        isTalking = false;
    }


    private void MoveMouth()
    {
        if (!isTalking)
        {
            return;
        }

        if (mouthTransform.localScale == mouthClosedScale)
        {
            mouthTransform.DOScale(mouthOpenScale, mouthMovementDuration);
        }
        else
        {
            mouthTransform.DOScale(mouthClosedScale, mouthMovementDuration);
        }

        Invoke("MoveMouth", mouthMovementDuration + 0.01f);
    }
}