2D物体一直朝向某个2D物体（LookAt2D）

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

public class Look2D : MonoBehaviour {

    [SerializeField]
    private Transform _targetPos;
    private void Update()
    {
        transform.eulerAngles = LookTargetAngle(transform, _targetPos.position);
    }
    public Vector3 LookTargetAngle(Transform playerTrans, Vector3 targetPos)
    {
       
        float dx = targetPos.x - playerTrans.transform.position.x;
        float dy = targetPos.y - playerTrans.transform.position.y;
        float rotationZ = Mathf.Atan2(dy, dx) * 180 / Mathf.PI;
        //得到最终的角度并且确保在 [0, 360) 这个区间内
        rotationZ -= 90;
        //获取增加的角度
        float originRotationZ = playerTrans.eulerAngles.z;
        float addRotationZ = rotationZ - originRotationZ;
        //超过 180 度需要修改为负方向的角度
        if (addRotationZ > 180)
        {
            addRotationZ -= 360;
        }
        //应用旋转
        return new Vector3(0, 0, playerTrans.eulerAngles.z + addRotationZ);
    }

}