Unity 如何使对象（文本（Text)模型精灵等）正面始终面向屏幕

using UnityEngine;
using System.Collections;
 
public class CameraFacingBillboard : MonoBehaviour
{
    public Camera m_Camera;
 
    //Orient the camera after all movement is completed this frame to avoid jittering
    void LateUpdate()
    {
        transform.LookAt(transform.position + m_Camera.transform.rotation * Vector3.forward,
            m_Camera.transform.rotation * Vector3.up);
    }
}

请注意，脚本不仅将对象指向相机。取而代之的是，它使对象指向与照相机前向轴相同的方向（即照相机向内看的方向）。从直觉上看，这可能是错误的，但实际上对于实时计算机图形的单点观点是正确的。

//    CameraFacing.cs 
//    original by Neil Carter (NCarter)
//    modified by Hayden Scott-Baron (Dock) - http://starfruitgames.com
//  allows specified orientation axis
 
 
using UnityEngine;
using System.Collections;
 
public class CameraFacing : MonoBehaviour
{
    Camera referenceCamera;
 
    public enum Axis {up, down, left, right, forward, back};
    public bool reverseFace = false; 
    public Axis axis = Axis.up; 
 
    // return a direction based upon chosen axis
    public Vector3 GetAxis (Axis refAxis)
    {
        switch (refAxis)
        {
            case Axis.down:
                return Vector3.down; 
            case Axis.forward:
                return Vector3.forward; 
            case Axis.back:
                return Vector3.back; 
            case Axis.left:
                return Vector3.left; 
            case Axis.right:
                return Vector3.right; 
        }
 
        // default is Vector3.up
        return Vector3.up;         
    }
 
    void  Awake ()
    {
        // if no camera referenced, grab the main camera
        if (!referenceCamera)
            referenceCamera = Camera.main; 
    }
        //Orient the camera after all movement is completed this frame to avoid jittering
    void LateUpdate ()
    {
        // rotates the object relative to the camera
        Vector3 targetPos = transform.position + referenceCamera.transform.rotation * (reverseFace ? Vector3.forward : Vector3.back) ;
        Vector3 targetOrientation = referenceCamera.transform.rotation * GetAxis(axis);
        transform.LookAt (targetPos, targetOrientation);
    }
}