血条是用GUI做的矩形,给矩形添加的颜色会变成Image, 当血满时Color为（1，1，0）就是黄的，（1，0，0）是红的，当血掉时（1，剩余血/满血，0）血条就会变红。当然想牛逼一点，可以先（0，1，0）绿色，前面一半血时可以（(满血-剩血)/半血，1，0），到后面一半时可以（1，剩血/半血，0）这样血就从绿色渐变成红色，半血时是黄的。
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;
using UnityEngine.UI;public class GameController : MonoBehaviour {public GameObject LifeBar;private Image image;public GameObject Coin;public GameObject Heart;public GameObject Bomb;public int EnemyCount;public Vector3 spawnValues;public Vector3 spawnValues2;public float[] a=new float[7];public int totalTime;private float nextTime=1;public GUIText textScore;public GUIText textHP;public GUIText textGameOver;public Text textClock;public float HP;private float HP_s;private float Width;private float Height;private RectTransform rect_T;private int totalScore = 0;private bool GameOver = false;//private Image image;//private RectTransform rect_T;// Use this for initializationvoid Start () {HP_s = HP;textScore.text = "Score: 0";textHP.text = "HP: " + HP;textGameOver.gameObject.SetActive (false);/*LifeBar=GameObject.FindGameObjectWithTag("LifeBar");image = LifeBar.GetComponent<Image> ();rect_T = LifeBar.GetComponent<RectTransform>();Rect rect = rect_T.rect;Width = rect.width;Height = rect.height;*/image = LifeBar.GetComponent<Image> ();rect_T = LifeBar.GetComponent<RectTransform>();Rect rect = rect_T.rect;Width = rect.width;Height = rect.height;StartCoroutine ("ClockTime");}public void DecreaseHP(int damage){HP -= damage;textHP.text = "HP: " + HP;rect_T.sizeDelta = new Vector2 ((HP / HP_s) * Width, Height);image.color = new Color (1,(HP / HP_s) , 0,1);}}