unity中3dUI始终面向摄像机，跟随摄像机视角旋转而旋转

3dUI始终面向摄像机，广告牌效果

public class SimpleBillboard : MonoBehaviour
{
    public bool IsStopInSceneView = false;
    void OnDrawGizmos()
    {
        if (IsStopInSceneView == false && Application.isPlaying == false && SceneView.currentDrawingSceneView.camera != null)
        {
            Rot(SceneView.currentDrawingSceneView.camera.
                transform);
        }
    }
 
    void Update()
    {
          Rot(Camera.main.camera.transform);
    }
 
    void Rot(Transform target)
    {
        Plane plane = new Plane(target.forward, target.position);
        float dis;
        Vector3 tar = target.position;
        if (plane.Raycast(new Ray(this.transform.position, -target.forward),out dis) == true)
        {
            tar = this.transform.position + (-target.forward * dis);
        }
        this.transform.LookAt(tar, Vector3.up);
    }
}