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

public class FocusCamera : MonoBehaviour
{
    public float MaxDis;
    public float maxScale;
    public float factor;

    private Transform cam;
    private SpriteRenderer spriteRenderer;
    private float distance;

    // Start is called before the first frame update
    void Start()
    {
        cam = Camera.main.transform;
        spriteRenderer = this.GetComponent<SpriteRenderer>();
    }

    // Update is called once per frame
    void Update()
    {
        transform.rotation = cam.rotation;

        //distance = Mathf.Abs(Vector3.Distance(transform.position, cam.position));
        //Debug.Log("before =" + distance);

        float dotResult = Vector3.Dot(cam.forward, (transform.position - cam.position).normalized);
        float angle = Mathf.Acos(dotResult) * Mathf.Rad2Deg;
        angle = angle > 90 ? 180 - angle : angle;
        distance = Mathf.Cos(angle * Mathf.Deg2Rad) * Mathf.Abs(Vector3.Distance(transform.position, cam.position));
        //Debug.Log(angle + "   after =" + distance);

        if (distance > MaxDis)
        {
            transform.localScale = Vector3.one * maxScale;
        }
        else
        {
            transform.localScale = Vector3.one * (distance / factor);
        }
    }

}