示例：利用UGUI的Text显示角色名称

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
/// <summary>
/// 角色头顶名字
/// </summary>
public class UIHeadText : MonoBehaviour
{
    [SerializeField]
    private Text m_Text;
    [SerializeField]
    private Outline outline;
    public Transform target; //文字要跟随的目标
    public Vector3 offset; //文字偏移量
    private RectTransform rectTransform;

    void Awake()
    {
        if (rectTransform == null)
            rectTransform = this.GetComponent<RectTransform>();
    }

    void Update()
    {
        if (target == null || target.gameObject == null)
            return;

        //Screen Space - Overlay 渲染模式下屏幕坐标与世界坐标等价
        //屏幕左下角为(0, 0)，右上角为(Screen.width, Screen.height)
        Vector3 position = target.position + offset;
        Vector3 screenPoint = Camera.main.WorldToScreenPoint(position);
        rectTransform.anchoredPosition = screenPoint;
    }

    public string Text
    {
        get {
            return m_Text.text;
        }
        set {
            m_Text.text = value;
        }
    }

    public Color TextColor
    {
        get {
            return m_Text.color;
        }
        set {
            m_Text.color = value;
        }
    }

    public Color OutlineColor
    {
        get
        {
            if (outline == null)
                return Color.white;
            return outline.effectColor;
        }
        set
        {
            if (outline == null)
                return;
            outline.effectColor = value;
        }
    }
}

效果

第二版

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
/// <summary>
/// 玩家头顶信息 (跟随玩家移动)
/// </summary>
public class UIHeadInfo : GameEventBehaviour
{
    [SerializeField]
    private RectTransform rectTransform;
    [SerializeField]
    private Text nameText;
    [SerializeField]
    private Vector3 offset;
    public Transform target;
    public float scaleFactor = 1;

    protected override void OnIDestroy()
    {
        target = null;
    }

    protected override void OnUpdate()
    {
        if (target == null || target.gameObject == null)
            return;

        //Screen Space - Overlay 渲染模式下屏幕坐标与世界坐标等价
        //屏幕左下角为(0, 0)，右上角为(Screen.width, Screen.height)
        Vector3 position = target.position + offset;
        Vector3 screenPoint = Camera.main.WorldToScreenPoint(position);
        Vector3 pos = screenPoint / scaleFactor;
        pos.x = Mathf.Ceil(pos.x);
        pos.y = Mathf.Ceil(pos.y);
        pos.z = Mathf.Ceil(pos.z);
        rectTransform.anchoredPosition = pos;
    }

    public void SetName(string name)
    {
        nameText.text = name;
    }

    // 创建头顶信息, target: 要跟随的目标
    public static UIHeadInfo Create(Transform target)
    {
        GameObject canvas = GameObject.FindGameObjectWithTag("Canvas");
        if (canvas == null)
        {
            Debug.LogError("Canvas not found, failed to create UIHeadInfo.");
            return null;
        }
        Canvas canvas_com = canvas.GetComponent<Canvas>();
        GameObject go = Resources.Load<GameObject>("UI/Prefab/UIHeadInfo");
        go = GameObject.Instantiate<GameObject>(go);
        go.transform.SetParent(canvas.transform);
        go.transform.localPosition = Vector3.zero;
        go.transform.localRotation = Quaternion.identity;
        go.transform.localScale = Vector3.one;
        UIHeadInfo headInfo = go.GetComponent<UIHeadInfo>();
        headInfo.target = target;
        headInfo.scaleFactor = canvas_com.scaleFactor;
        return headInfo;
    }
}

示例：世界坐标转屏幕坐标

// 世界坐标转屏幕坐标
public Vector3 WorldToScreenPoint(Vector3 worldPos)
{
    //屏幕坐标系原点在左下角
    Vector3 pos = Camera.main.WorldToScreenPoint(worldPos);
    //Canvas坐标原点在屏幕中心
    //与Canvas坐标原点对齐
    pos.x -= canvas.pixelRect.width / 2;
    pos.y -= canvas.pixelRect.height / 2;
    //适配不同分辨率
    pos = pos / canvas.scaleFactor;
    //去掉小数，避免抖动
    pos.x = Mathf.Ceil(pos.x);
    pos.y = Mathf.Ceil(pos.y);
    pos.z = Mathf.Ceil(pos.z);
    return pos;
}