UnityAI——动物迁徙中的跟随实现实例

七七喝椰奶2023-11-14 1:30

大家好，我是七七，今天来给大家介绍的是Unity中用操控行为实现的跟随领队行为。

看本文若是想了解和实现，只看本文即可，若是想彻底弄透，建议从七七的游戏AI专栏开始看。

废话不多说，先上视频：

跟随队长

我们的目标是让后面的人跟着领头的人，并遵循一些规则

对于领头的人：

  1. 随机地移动
  2. 检测前方是否有人

对于跟随的人；

  1. 跟的不要太近
  2. 人与人直接不要拥挤
  3. 如果发现挡道领头人路了，赶紧让开

我们只需要实现这些规则，就可以得到理想的效果，这与神经网络的思想类似，下面我们就来实现这些规则。

规则1

这个脚本是挂载领头人身上的，目的是在前方LEADER_BEHIND_DIST处画一个圆球，若是说前方有人，则让这些人避开。

cs 复制代码 
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class DrawGizmos : MonoBehaviour
{
    public float evadeDistance;
    public Vector3 center;
    private Vehicle vehicleScript;
    private float LEADER_BEHIND_DIST;

    void Start()
    {
        vehicleScript = GetComponent<Vehicle>();
        LEADER_BEHIND_DIST = 2.0f;
    }

    void Update()
    {
        center = transform.position + vehicleScript.velocity.normalized * LEADER_BEHIND_DIST;
    }
    void OnDrawGizoms()
    {
        Gizmos.DrawWireSphere(center, evadeDistance);
    }
}

规则2

这个脚本是挂在一个空物体上的，目的是生成多个跟随者

cs 复制代码 
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class GenerateBotsForFollowLeader : MonoBehaviour
{
    public GameObject botPrefab;
    public GameObject leader;
    public int botCount;
    public float minX = -5f;
    public float maxX = 5.0f;
    public float minZ = -5.0f;
    public float maxZ = 5.0f;
    public float Yvalue = 1.026003f;

    void Start()
    {
        Vector3 spawnPosition;
        GameObject bot;
        for(int i = 0; i < botCount; i++)
        {
            spawnPosition = new Vector3(Random.Range(minX, maxX), Yvalue, Random.Range(minZ, maxZ));//随机产生一个生成位置
            bot = Instantiate(botPrefab, spawnPosition, Quaternion.identity) as GameObject;
            bot.GetComponent<SteeringForLeaderFollowing>().leader = leader;
            bot.GetComponent<SteeringForEvade>().target = leader;
            bot.GetComponent<SteeringForEvade>().enabled = false;
            bot.GetComponent<EvadeController>().leader = leader;
        }
    }
}

规则3

这个脚本是挂在跟随者身上的，是为了确定跟随者的路径目标点，即领导人身后LEADER_BEHIND_DIST处

cs 复制代码 
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
[RequireComponent(typeof(SteeringForArrive))]
public class SteeringForLeaderFollowing : Steering
{
    public Vector3 target;
    private Vector3 desiredVelocity;//预期速度
    private Vehicle m_vehicle;//获得被操控的AI角色
    private float maxSpeed;
    private bool isPlanar;
    public GameObject leader;
    private Vehicle leaderController;
    private Vector3 leaderVelocity;
    private float LEADER_BEHIND_DIST=2.0f;
    private SteeringForArrive arriveScript;
    private Vector3 randomOffset;
    void Start()
    {
        m_vehicle = GetComponent<Vehicle>();
        maxSpeed = m_vehicle.maxSpeed;
        isPlanar = m_vehicle.isPlanar;
        leaderController=leader.GetComponent<Vehicle>();
        arriveScript= GetComponent<SteeringForArrive>();//为抵达行为指定目标点
        arriveScript.target = new GameObject("arriveTarget");
        arriveScript.target.transform.position = leader.transform.position;
    }

   public override Vector3 Force()
    {
        leaderVelocity = leaderController.velocity;
        target=leader.transform.position+LEADER_BEHIND_DIST*(-leaderVelocity).normalized;//计算目标点
        arriveScript.target.transform.position = target;
        return new Vector3(0, 0, 0);
    }
}

规则4

这个脚本是挂在跟随者身上的，目的是为了避免跟随者挡住领导人的路

cs 复制代码 
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class EvadeController : MonoBehaviour
{
    public GameObject leader;
    private Vehicle leaderLocomotion;
    private Vehicle m_vehicle;
    private bool isPlanar;
    private Vector3 leaderAhead;
    private float LEADER_BEHIND_DIST;
    private Vector3 dist;
    public float evadeDistance;
    private float sqrEvadeDistance;
    private SteeringForEvade evadeScript;

    void Start()
    {
        leaderLocomotion = leader.GetComponent<Vehicle>();
        evadeScript= GetComponent<SteeringForEvade>();
        m_vehicle= GetComponent<Vehicle>();
        isPlanar=m_vehicle.isPlanar;
        LEADER_BEHIND_DIST = 2.0f;
        sqrEvadeDistance=sqrEvadeDistance*sqrEvadeDistance;
    }

  
    void Update()
    {
        leaderAhead=leader.transform.position+leaderLocomotion.velocity.normalized*LEADER_BEHIND_DIST;  //计算领队前方的一个点
        dist = transform.position - leaderAhead;
        if (isPlanar)
        {
            dist.y = 0;
        }
        if(dist.sqrMagnitude < sqrEvadeDistance)
        {
            evadeScript.enabled = true;
            Debug.DrawLine(transform.position, leader.transform.position);
        }
        else
        {
            evadeScript.enabled = false;
        }
    }
}

实现

前提

有3个基类

UnityAI------操控行为编程的主要基类-CSDN博客

第一步

创建一个场景，一个Plane

第二步

创建一个Cube作为领队，起名为Leader，为其挂上三个脚本，如下所示：

cs 复制代码 
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class AILocomotion : Vehicle
{
    private CharacterController controller;  //AI�Ľ�ɫ������
    private Rigidbody theRigidbody;
    private Vector3 moveDistance;//AI��ɫÿ�ε��ƶ�����

    void Start()
    {
        controller = GetComponent<CharacterController>();
        theRigidbody = GetComponent<Rigidbody>();
        moveDistance = new Vector3(0, 0, 0);
        base.Start();//���û����start��������������ij�ʼ��
    }

    //������ز�����FixedUpdate�и���
    void FixedUpdate()
    {
        velocity += acceleration * Time.fixedDeltaTime;//�����ٶ�
        if (velocity.sqrMagnitude > sqrMaxSpeed)   //��������ٶ�
        velocity = velocity.normalized * maxSpeed;
        moveDistance = velocity * Time.fixedDeltaTime;
        if (isPlanar)  
        {
            velocity.y = 0;
            moveDistance.y = 0;
        }
        if (controller != null)//����Ѿ�ΪAI��ɫ���ӽ�ɫ����������ô���ý�ɫ������ʹ���ƶ�
            controller.SimpleMove(velocity);
        //�����ɫ��û��ɫ��������ҲûRigidbody
        //����Rigidbody����Ҫ�ɶ���ѧ�ķ�ʽ�������ƶ�
        else if (theRigidbody == null || !theRigidbody.isKinematic)
            transform.position += moveDistance;
        else //��Rigidbody���ƽ�ɫ���˶�
            theRigidbody.MovePosition(theRigidbody.position+moveDistance);
        if(velocity.sqrMagnitude>0.00001)//���³�������ٶȴ���һ����ֵ��Ϊ�˷�ֹ������
        {
            Vector3 newForward = Vector3.Slerp(transform.forward, velocity, damping * Time.deltaTime);
            if(isPlanar)
                newForward.y = 0;
            transform.forward = newForward;
        }
        //�������߶���
        gameObject.GetComponent<Animation>().Play("walk");
    }
}
cs 复制代码 
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class SteeringForWander : Steering
{

    public float wanderRadius; //徘徊半径
    public float wanderDistance; //徘徊距离
    public float wanderJitter; //每秒加到目标的随即位移的最大值
    public bool isPlanar;
    private Vector3 desiredVelocity;//预期速度
    private Vehicle m_vehicle;//获得被操控的AI角色
    private float maxSpeed;
    private Vector3 circleTarget;
    private Vector3 wanderTarget;
    void Start()
    {
        m_vehicle = GetComponent<Vehicle>();
        maxSpeed = m_vehicle.maxSpeed;
        isPlanar = m_vehicle.isPlanar;
        circleTarget = new Vector3(wanderRadius * 0.707f, 0, wanderRadius * 0.707f);  //选取与安全上的一个点作为初始点
    }

    public override Vector3 Force()
    {
        Vector3 randomDisplacement = new Vector3((Random.value - 0.5f) * 2 * wanderJitter, (Random.value - 0.5f) * 2 * wanderJitter, (Random.value - 0.5f) * 2 * wanderJitter);
        if (isPlanar)
            randomDisplacement.y = 0;
        circleTarget+=randomDisplacement;//将随机位移加到初始点上
        circleTarget = wanderRadius * circleTarget.normalized;//由于新位置很可能不在圆周上，因此需要投影到圆周上
        wanderTarget = m_vehicle.velocity.normalized * wanderDistance + circleTarget + transform.position;//之前计算出的值是相对于AI的，需要转换为世界坐标
        desiredVelocity = (wanderTarget - transform.position).normalized * maxSpeed;
        return (desiredVelocity - m_vehicle.velocity);
    }
}
cs 复制代码 
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class DrawGizmos : MonoBehaviour
{
    public float evadeDistance;
    public Vector3 center;
    private Vehicle vehicleScript;
    private float LEADER_BEHIND_DIST;

    void Start()
    {
        vehicleScript = GetComponent<Vehicle>();
        LEADER_BEHIND_DIST = 2.0f;
    }

    void Update()
    {
        center = transform.position + vehicleScript.velocity.normalized * LEADER_BEHIND_DIST;
    }
    void OnDrawGizoms()
    {
        Gizmos.DrawWireSphere(center, evadeDistance);
    }
}

第三步

创建一个空物体，起名为follersGenerator，用于生成跟随者，并添加脚本

cs 复制代码 
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class GenerateBotsForFollowLeader : MonoBehaviour
{
    public GameObject botPrefab;
    public GameObject leader;
    public int botCount;
    public float minX = -5f;
    public float maxX = 5.0f;
    public float minZ = -5.0f;
    public float maxZ = 5.0f;
    public float Yvalue = 1.026003f;

    void Start()
    {
        Vector3 spawnPosition;
        GameObject bot;
        for(int i = 0; i < botCount; i++)
        {
            spawnPosition = new Vector3(Random.Range(minX, maxX), Yvalue, Random.Range(minZ, maxZ));//随机产生一个生成位置
            bot = Instantiate(botPrefab, spawnPosition, Quaternion.identity) as GameObject;
            bot.GetComponent<SteeringForLeaderFollowing>().leader = leader;
            bot.GetComponent<SteeringForEvade>().target = leader;
            bot.GetComponent<SteeringForEvade>().enabled = false;
            bot.GetComponent<EvadeController>().leader = leader;
        }
    }
}

第四步

创建一个方块预设，作为跟随者，挂上下列脚本：

cs 复制代码 
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class AILocomotion : Vehicle
{
    private CharacterController controller;  //AI�Ľ�ɫ������
    private Rigidbody theRigidbody;
    private Vector3 moveDistance;//AI��ɫÿ�ε��ƶ�����

    void Start()
    {
        controller = GetComponent<CharacterController>();
        theRigidbody = GetComponent<Rigidbody>();
        moveDistance = new Vector3(0, 0, 0);
        base.Start();//���û����start��������������ij�ʼ��
    }

    //������ز�����FixedUpdate�и���
    void FixedUpdate()
    {
        velocity += acceleration * Time.fixedDeltaTime;//�����ٶ�
        if (velocity.sqrMagnitude > sqrMaxSpeed)   //��������ٶ�
        velocity = velocity.normalized * maxSpeed;
        moveDistance = velocity * Time.fixedDeltaTime;
        if (isPlanar)  
        {
            velocity.y = 0;
            moveDistance.y = 0;
        }
        if (controller != null)//����Ѿ�ΪAI��ɫ���ӽ�ɫ����������ô���ý�ɫ������ʹ���ƶ�
            controller.SimpleMove(velocity);
        //�����ɫ��û��ɫ��������ҲûRigidbody
        //����Rigidbody����Ҫ�ɶ���ѧ�ķ�ʽ�������ƶ�
        else if (theRigidbody == null || !theRigidbody.isKinematic)
            transform.position += moveDistance;
        else //��Rigidbody���ƽ�ɫ���˶�
            theRigidbody.MovePosition(theRigidbody.position+moveDistance);
        if(velocity.sqrMagnitude>0.00001)//���³�������ٶȴ���һ����ֵ��Ϊ�˷�ֹ������
        {
            Vector3 newForward = Vector3.Slerp(transform.forward, velocity, damping * Time.deltaTime);
            if(isPlanar)
                newForward.y = 0;
            transform.forward = newForward;
        }
        //�������߶���
        gameObject.GetComponent<Animation>().Play("walk");
    }
}
cs 复制代码 
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class SteeringForArrive : Steering
{
    public bool isPlanar = true;
    public float arrivalDistance = 0.3f;
    public float characterRadius = 1.2f;
    public float slowDownDistance;
    public GameObject target;
    private Vector3 desiredVelocity;//预期速度
    private Vehicle m_vehicle;//获得被操控的AI角色
    private float maxSpeed;
    void Start()
    {
        m_vehicle = GetComponent<Vehicle>();
        maxSpeed = m_vehicle.maxSpeed;
        isPlanar = m_vehicle.isPlanar;
    }
    public override Vector3 Force()
    {
        Vector3 toTarget = target.transform.position - transform.position;
        Vector3 desiredVelocity;
        Vector3 returnForce;
        if (isPlanar)
            toTarget.y = 0;
        float distance = toTarget.magnitude;
        if (distance > slowDownDistance)
        {
            desiredVelocity = toTarget.normalized * maxSpeed;
            returnForce = desiredVelocity - m_vehicle.velocity;
        }
        else
        {
            desiredVelocity = toTarget - m_vehicle.velocity;
            returnForce = desiredVelocity - m_vehicle.velocity;
        }
        return returnForce;
    }
    void OnDrawGizmos()
    {
        Gizmos.DrawWireSphere(target.transform.position, slowDownDistance);
    }
}
cs 复制代码 
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
[RequireComponent(typeof(SteeringForArrive))]
public class SteeringForLeaderFollowing : Steering
{
    public Vector3 target;
    private Vector3 desiredVelocity;//预期速度
    private Vehicle m_vehicle;//获得被操控的AI角色
    private float maxSpeed;
    private bool isPlanar;
    public GameObject leader;
    private Vehicle leaderController;
    private Vector3 leaderVelocity;
    private float LEADER_BEHIND_DIST=2.0f;
    private SteeringForArrive arriveScript;
    private Vector3 randomOffset;
    void Start()
    {
        m_vehicle = GetComponent<Vehicle>();
        maxSpeed = m_vehicle.maxSpeed;
        isPlanar = m_vehicle.isPlanar;
        leaderController=leader.GetComponent<Vehicle>();
        arriveScript= GetComponent<SteeringForArrive>();//为抵达行为指定目标点
        arriveScript.target = new GameObject("arriveTarget");
        arriveScript.target.transform.position = leader.transform.position;
    }

   public override Vector3 Force()
    {
        leaderVelocity = leaderController.velocity;
        target=leader.transform.position+LEADER_BEHIND_DIST*(-leaderVelocity).normalized;//计算目标点
        arriveScript.target.transform.position = target;
        return new Vector3(0, 0, 0);
    }
}
cs 复制代码 
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Radar : MonoBehaviour
{
    private Collider[] colliders;//碰撞体的组数
    private float timer = 0;//计时器
    public List<GameObject> neighbors;
    public float checkInterval = 0.3f;//设置检测的时间间隔
    public float detectRadius = 10f;//设置邻域半径
    public LayerMask layersChecked;//设置检测哪一层的游戏对象

    void Start()
    {
        neighbors = new List<GameObject>();
    }

    void Update()
    {
        timer += Time.deltaTime;
        if(timer > checkInterval)
        {
            neighbors.Clear();
            colliders = Physics.OverlapSphere(transform.position, detectRadius, layersChecked);//查找当前AI角色邻域内的所有碰撞体
            for(int i = 0; i < colliders.Length; i++)//对于每个检测到的碰撞体，获取Vehicle组件，并且加入邻居列表钟
            {
                if (colliders[i].GetComponent<Vehicle>())
                    neighbors.Add(colliders[i].gameObject);
            }
            timer = 0;
        }
    }
}
cs 复制代码 
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class SteeringForSeparation : Steering
{
    public float comforDistance = 1;//可接受的距离
    public float multiplierInsideComfortDistance = 2;//当AI角色与邻居距离过近时的惩罚因子
 public override Vector3 Force()
    {
        Vector3 steeringForce = new Vector3(0, 0, 0);
        foreach(GameObject s in GetComponent<Radar>().neighbors)//遍历这个AI角色的邻居列表中的每个邻居
        {
            if ((s != null) && (s != this.gameObject))
            {
                Vector3 toNeighbor = transform.position - s.transform.position;//计算当前AI角色与邻居s之间的距离
                float length=toNeighbor.magnitude;
                steeringForce += toNeighbor.normalized / length;//计算这个邻居引起的操控力
                if (length < comforDistance)
                    steeringForce *= multiplierInsideComfortDistance;
            }
        }
        return steeringForce;
    }
}
cs 复制代码 
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class SteeringForEvade :Steering
{

    public GameObject target;
    private Vector3 desiredVelocity;//预期速度
    private Vehicle m_vehicle;//获得被操控的AI角色
    private float maxSpeed;

    void Start()
    {
        m_vehicle = GetComponent<Vehicle>();
        maxSpeed = m_vehicle.maxSpeed;

    }
    public override Vector3 Force()
    {
        Vector3 toTarget = target.transform.position - transform.position;
        float lookaheadTime = toTarget.magnitude / (maxSpeed + target.GetComponent<Vehicle>().velocity.magnitude);//向前预测的时间
        desiredVelocity = (transform.position - (target.transform.position+target.GetComponent<Vehicle>().velocity*lookaheadTime)).normalized * maxSpeed;
        return (desiredVelocity - m_vehicle.velocity);
    }
}
cs 复制代码 
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class EvadeController : MonoBehaviour
{
    public GameObject leader;
    private Vehicle leaderLocomotion;
    private Vehicle m_vehicle;
    private bool isPlanar;
    private Vector3 leaderAhead;
    private float LEADER_BEHIND_DIST;
    private Vector3 dist;
    public float evadeDistance;
    private float sqrEvadeDistance;
    private SteeringForEvade evadeScript;

    void Start()
    {
        leaderLocomotion = leader.GetComponent<Vehicle>();
        evadeScript= GetComponent<SteeringForEvade>();
        m_vehicle= GetComponent<Vehicle>();
        isPlanar=m_vehicle.isPlanar;
        LEADER_BEHIND_DIST = 2.0f;
        sqrEvadeDistance=sqrEvadeDistance*sqrEvadeDistance;
    }

  
    void Update()
    {
        leaderAhead=leader.transform.position+leaderLocomotion.velocity.normalized*LEADER_BEHIND_DIST;  //计算领队前方的一个点
        dist = transform.position - leaderAhead;
        if (isPlanar)
        {
            dist.y = 0;
        }
        if(dist.sqrMagnitude < sqrEvadeDistance)
        {
            evadeScript.enabled = true;
            Debug.DrawLine(transform.position, leader.transform.position);
        }
        else
        {
            evadeScript.enabled = false;
        }
    }
}

收尾

最后再给各个角色装上刚体，设置好Leader等参数就可以了。

很多行为我们都可以通过设定规则来实现，可能乍一看行为很难摸索，但慢慢分析出其中的规则并逐一实现后，问题往往就会被解决

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