unity世界坐标转屏幕坐标

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class HPFollow : MonoBehaviour
{
    public Transform heroHead;
    public Camera camera;
    public RectTransform hp;
    public RectTransform canvasTransform;
    void Update()
    {
        Vector2 screenPoint = RectTransformUtility.WorldToScreenPoint(camera, heroHead.position);// 先将3D坐标转换成屏幕坐标
        Vector2 localPoint;// 再将屏幕坐标转换成UGUI坐标
        if (RectTransformUtility.ScreenPointToLocalPointInRectangle(canvasTransform, screenPoint, camera, out localPoint))
        {
            //这里的camera可以是null 如果canvas是Screen Space-Overlay渲染模式的话
            //如果是Screen Space-Camera模式的话 就是对应拖到Canvas上的相机
            // canvasTransform 是(hp的父节点或者是canvas) hp.parent.GetComponent<RectTransform>()
            hp.anchoredPosition = localPoint;
        }
    }
}