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

public class Billboard : MonoBehaviour
{
    [Header("Position")]
    public float distanceFromCamera = 2.0f; 
    public Vector3 offset = Vector3.zero;

    [Header("Smoothing")]
    [Range(0.01f, 20f)]
    public float moveSmoothSpeed = 5f;
    [Range(0.01f, 20f)]
    public float rotateSmoothSpeed = 5f;

    private Transform mainCamera;

    void Start()
    {
        if (Camera.main != null)
        {
            mainCamera = Camera.main.transform;
        }
        else
        {
            Debug.LogWarning("Main Camera not found.");
        }
    }

    void LateUpdate()
    {
        if (mainCamera == null) return;

        // Calculate target position in field of view
        Vector3 targetPosition = mainCamera.position + mainCamera.forward * distanceFromCamera + mainCamera.TransformVector(offset);

        transform.position = Vector3.Lerp(transform.position, targetPosition, moveSmoothSpeed * Time.deltaTime);

        Vector3 directionToCamera = transform.position - mainCamera.position;
        directionToCamera.y = 0f; // only horizontal orientation

        if (directionToCamera.sqrMagnitude > 0.001f)
        {
            Quaternion targetRotation = Quaternion.LookRotation(directionToCamera);
            transform.rotation = Quaternion.Slerp(transform.rotation, targetRotation, rotateSmoothSpeed * Time.deltaTime);
        }
    }
}