Unity3D人物头顶名称与血条更新与绘制

using UnityEngine;
using System.Collections;
 
public class NPC : MonoBehaviour {
 
    //主摄像机对象
    private Camera camera;
    //NPC名称
    private string name = "我是雨松MOMO";
 
    //主角对象
    GameObject hero;
    //NPC模型高度
    float npcHeight;
    //红色血条贴图
    public Texture2D blood_red;
    //黑色血条贴图
    public Texture2D blood_black;
    //默认NPC血值
    private int HP = 100;
 
    void Start ()
    {
        //根据Tag得到主角对象
        hero = GameObject.FindGameObjectWithTag("Player");
        //得到摄像机对象
        camera = Camera.main;
 
        //注解1
        //得到模型原始高度
        float size_y = collider.bounds.size.y;
        //得到模型缩放比例
        float scal_y = transform.localScale.y;
        //它们的乘积就是高度
        npcHeight = (size_y *scal_y) ;
 
    }
 
    void Update ()
    {
        //保持NPC一直面朝主角
        transform.LookAt(hero.transform);
    }
 
    void OnGUI()
    {
        //得到NPC头顶在3D世界中的坐标
        //默认NPC坐标点在脚底下，所以这里加上npcHeight它模型的高度即可
        Vector3 worldPosition = new Vector3 (transform.position.x , transform.position.y + npcHeight,transform.position.z);
        //根据NPC头顶的3D坐标换算成它在2D屏幕中的坐标
        Vector2 position = camera.WorldToScreenPoint (worldPosition);
        //得到真实NPC头顶的2D坐标
        position = new Vector2 (position.x, Screen.height - position.y);
        //注解2
        //计算出血条的宽高
        Vector2 bloodSize = GUI.skin.label.CalcSize (new GUIContent(blood_red));
 
        //通过血值计算红色血条显示区域
        int blood_width = blood_red.width * HP/100;
        //先绘制黑色血条
        GUI.DrawTexture(new Rect(position.x - (bloodSize.x/2),position.y - bloodSize.y ,bloodSize.x,bloodSize.y),blood_black);
        //在绘制红色血条
        GUI.DrawTexture(new Rect(position.x - (bloodSize.x/2),position.y - bloodSize.y ,blood_width,bloodSize.y),blood_red);
 
        //注解3
        //计算NPC名称的宽高
        Vector2 nameSize = GUI.skin.label.CalcSize (new GUIContent(name));
        //设置显示颜色为黄色
        GUI.color  = Color.yellow;
        //绘制NPC名称
        GUI.Label(new Rect(position.x - (nameSize.x/2),position.y - nameSize.y - bloodSize.y ,nameSize.x,nameSize.y), name);
 
    }
 
    //下面是经典鼠标点击对象的事件，大家看一下就应该知道是什么意思啦。
    void OnMouseDrag ()
    {
        Debug.Log("鼠标拖动该模型区域时");
    }
 
    void OnMouseDown()
    {
        Debug.Log("鼠标按下时");
 
        if(HP >0)
        {
            HP -=5 ;
        }
 
    }
    void OnMouseUp()
    {
        Debug.Log("鼠标抬起时");
    }
 
    void OnMouseEnter()
    {
        Debug.Log("鼠标进入该对象区域时");
    }
    void OnMouseExit()
    {
        Debug.Log("鼠标离开该模型区域时");
    }
    void OnMouseOver()
    {
        Debug.Log("鼠标停留在该对象区域时");
    }
 
}