物体朝向摄像机

锁定物体的X轴旋转

========================================

using UnityEngine;
using System.Collections;

public class LookAtMainCamera : MonoBehaviour
{    
    public bool LookMode = false;

    void Update ()
    {
        var cameraPos = Camera.main.transform.position;
        var objPos = this.transform.position;
        var lookV = cameraPos - objPos;
        if (LookMode)
        {
            var crossValue = Vector3.Cross(Vector3.up, lookV);
            var crossThis = Vector3.Cross(this.transform.up, crossValue);
            this.transform.localRotation = Quaternion.LookRotation(-crossThis, Vector3.up);
        } else
        {
            this.transform.LookAt(cameraPos, Vector3.up);
        }
    }
}

直接转向插值 或直接lookAt

====================================================

using UnityEngine;

public class LookAtCamera : MonoBehaviour {

    public float lerpFactor = 10f;
    // Use this for initialization
    void Start () {
        
    }
    
    // Update is called once per frame
    void Update () {
        //transform.LookAt(Camera.main.transform.position);
        transform.rotation = Quaternion.Slerp(transform.rotation,Quaternion.LookRotation(Camera.main.transform.position - transform.position), lerpFactor * Time.deltaTime);
    }
}