Unity 三维Ui面向摄像头且等比例缩放，保持大小不变

1、挂在到三维UI上，调整期望平面高度

using UnityEngine;  public class KeepModelScreenSize : MonoBehaviour {     public float desiredScreenHeight = 200f; // 期望的屏幕高度      private Transform mtr;     private Camera mainCamera;      private void Awake()     {         mtr = this.transform;         mainCamera = Camera.main;     }      void Update()     {         //欧拉角相等 面向相机         mtr.eulerAngles = mainCamera.transform.eulerAngles;          // 获取3D模型在屏幕上的位置         Vector3 screenPos = Camera.main.WorldToScreenPoint(transform.position);          // 计算模型在屏幕上的高度         float modelScreenHeight = Mathf.Abs((screenPos.y - Camera.main.WorldToScreenPoint(transform.position + transform.up).y));          // 计算缩放比例         float scaleRatio = desiredScreenHeight / modelScreenHeight;          // 设置缩放         transform.localScale = new Vector3(scaleRatio, scaleRatio, scaleRatio);     } }