Unity3D实现Billboard效果

功能：

写一个脚本，挂载此脚本的物体的Z轴始终朝向摄像机。在编辑状态，挂载这个脚本的物件要朝向Scene视图摄像机，在运行状态要朝向主摄像机。

运行时朝向主摄像机：

using UnityEngine;
using System.Collections;

public class LookAtCamera : MonoBehaviour
{
    // Update is called once per frame
    void Update()
    {
        transform.LookAt(Camera.main.transform.position, -Vector3.up);
    }
}

编辑状态（Scene视图）朝向Scene视图摄像机：

首先在Assets下新建文件夹Editor，在Editor中新建脚本

using UnityEngine;
using UnityEditor;

[CustomEditor(typeof(LookAtCamera))]
public class SceneCameraEditor : Editor {
    
    void OnSceneGUI()
    {
        LookAtCamera lookAtCamera = (LookAtCamera)target;
        lookAtCamera.transform.LookAt(UnityEditor.SceneView.lastActiveSceneView.camera.transform.position, -Vector3.up);
    }
	
}