Billboard.cs

// Code based on CameraFacingBillboard by Nei Carter: http://wiki.unity3d.com/index.php?title=CameraFacingBillboard

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Billboard : MonoBehaviour
{
    public Transform cameraTransform;
    
    void LateUpdate()
    {
        transform.LookAt(transform.position + cameraTransform.rotation * Vector3.forward, cameraTransform.rotation * Vector3.up);
    }
}