unity之遗传算法的简单使用-编程知识-夕阳导航

1、示例说明

前几天记了一下遗传算法的基本概念，我们知道，遗传算法就是模拟达尔文生物进化论而提出来的算法。这里提供一个遗传算法使用的简单示例，在这个示例中，有一条吃老鼠的蛇，这条蛇只吃体型较小的老鼠，老鼠种群经过N代繁殖，经历了物竞天择、适者生存的自然法则，最后基本都进化成了体型很大的老鼠，蛇吃不了它们，当然也有少数基因突变的老鼠体型还是很小，依然躲不过被蛇吃的命运。下面在unity中简单实现一下它：

2、定义老鼠个体类

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class RatItem : MonoBehaviour {
 public float size = 1;//大小
 public float survivalTime = 8;//存活时间
 //被蛇吃
 public void Dead()
 {
 survivalTime = Population.timeCount;
 gameObject.SetActive(false);
 }
 
}

3、定义老鼠种群管理类

using System.Collections;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;
using UnityEngine.UI;
public class Population : MonoBehaviour {
 public GameObject ratPrefab;//老鼠prefab
 public int populationSize = 10;//种群大小
 public List<GameObject> population = new List<GameObject>();//老鼠种群
 static List<GameObject> ratSize;
 public static float timeCount = 0;//计时
 private int trailInterval = 10;//每一代训练间隔
 private int count = 1;//第几代老鼠
 public float mutation = 0.1f;//基因突变概率
 public Text countText;//第几代显示
 public Text timeCountText;//时间显示
 void Start () {
 //初始化第一代种群
 for (int i = 0; i < populationSize; i++)
 {
 Vector3 pos = new Vector3(Random.Range(-3, 3), 0, Random.Range(-3, 3));
 GameObject go = Instantiate(ratPrefab, pos, Quaternion.identity);
 float randomSize= Random.Range(1, 4);
 go.GetComponent<RatItem>().size = randomSize;
 go.transform.localScale = new Vector3(randomSize, randomSize, randomSize);
 population.Add(go);
 }
 ratSize = population.OrderByDescending(go => go.GetComponent<RatItem>().size).ToList();
 }
 
 void Update () {
 //定时繁衍新一代
 timeCount += Time.deltaTime;
 if (timeCount > trailInterval)
 {
 BreedNewPopulation();
 timeCount = 0;
 }
 countText.text ="繁衍代数："+ count.ToString();
 timeCountText.text = "计时：" + timeCount.ToString();
 }
 //繁衍一代
 void BreedNewPopulation()
 {
 List<GameObject> newPopulation = new List<GameObject>();
 //给上一代个体列表按存活时间降序排序
 List<GameObject> sortedList = population.OrderByDescending(go => go.GetComponent<RatItem>().survivalTime).ToList();
 //清空上一代列表
 population.Clear();
 ratSize.Clear();
 //选择优良的两个父代（存活时间长）去繁殖新一代
 for (int i =0; i < (int)(sortedList.Count / 2); i++)
 {
 population.Add(Breed(sortedList[i].GetComponent<RatItem>(), sortedList[i + 1].GetComponent<RatItem>()));
 population.Add(Breed(sortedList[i + 1].GetComponent<RatItem>(), sortedList[i].GetComponent<RatItem>()));
 }
 ratSize = population.OrderByDescending(go => go.GetComponent<RatItem>().size).ToList();
 //销毁先前所有的种群
 for (int i = 0; i < sortedList.Count; i++)
 {
 Destroy(sortedList[i]);
 }
 count++;
 }
 //两个父代繁殖出新个体 (交叉)
 GameObject Breed(RatItem item1,RatItem item2)
 {
 Vector3 pos = new Vector3(Random.Range(-3, 3), 0, Random.Range(-3, 3));
 GameObject go = Instantiate(ratPrefab, pos, Quaternion.identity);
 RatItem item = go.GetComponent<RatItem>();
 //新个体随机继承父亲或母亲的基因
 if (Random.Range(0, 100) > mutation * 100)
 {
 float random= Random.Range(0, 1) > 0.5f ? item1.size : item2.size;
 item.size = random;
 go.transform.localScale = new Vector3(random, random, random);
 }
 //基因突变
 else
 {
 float random = Random.Range(0, 2);
 item.size = random;
 go.transform.localScale = new Vector3(random, random, random);
 }
 return go;
 }
 //得到体型最小的个体
 public static GameObject GetSmallRat()
 {
 if (ratSize.Count > 0)
 {
 GameObject go = ratSize[ratSize.Count - 1];
 go.GetComponent<RatItem>().Dead();
 ratSize.Remove(go);
 return go;
 }
 else
 return null;
 }
}

4、定义蛇类

using System.Collections;
using System.Collections.Generic;
using System.Linq;
using UnityEngine;
public class Snake : MonoBehaviour {
 public float interval = 2;//每三秒吃一只老鼠
 private float timeCount = 0;//计时
 
 // Update is called once per frame
 void Update () {
 timeCount += Time.deltaTime;
 if (timeCount > interval)
 {
 EatRat();
 timeCount = 0;
 }
 }
 //吃老鼠
 void EatRat()
 {
 GameObject go = Population.GetSmallRat();
 if (go != null)
 {
 if (go.GetComponent<RatItem>().size < 2.5f)
 {
 Debug.Log("吃只小老鼠！");
 go.GetComponent<RatItem>().Dead();
 }
 else
 Debug.Log("老鼠都太大了，我吃不下了！");
 }
 }
}

5、操作步骤与运行测试

在上述代码中，首先初始化第一代老鼠种群，蛇会吃了淘汰掉体型较小的老鼠，老鼠种群会挑选基因优良（存活时间长）的老鼠父代去繁衍下一代。在unity中，建好一个场景，并制作老鼠prefab，将RatItem类挂到该prefab上，准备好所有后运行场景：