Unity中的群組行為

一：效果演示

不使用群組演算法和使用群組演算法的演示視頻

二：什么是群組行為

群組行為屬于人工智能思想，比如說人群走路、鳥群飛行、魚群游動，群組中成員之間不應該很規律的運動，例如不能擁擠到一起，而是更加真實的去模擬現實中的場景
下面是不使用群組行為和使用群組行為的演示

群組中的三種行為：
——分隔：成員間保持一定距離，不能太近
——佇列：群組以相同的速度向相同方向運動
——聚集：避免與臨近成員距離太遠

三：群組行為中的三種行為

為了更好的模擬現實環境，使用施加力的方式替代直接修改物體速度，因為直接修改物體的速度會無視各種外力，而施加力是一種仿物理的方式

——分隔

當成員之間相距很近時，給其一個相反的力進行分離

——佇列

當與大部隊運動方向不一致時，給其一個力進行調整

——聚集

當與其他成員相距很遠時，就選取就近幾個成員的中心點，施加力實作聚集

四：代碼實作

using UnityEngine;

/// <summary>
/// 群組行為中的個體
/// </summary>
public class UnityFlock : MonoBehaviour
{
    public Transform target;//目標物體

    [Header("運動速度")]
    public float speed;
    [Header("物體質量")]
    private int m = 1;

    [Header("需要分離的距離")]
    [Header("====================")]
    public float separationDist;
    [Header("分離力的比重")]
    public float separationWeight;

    [Header("需要佇列的距離")]
    public float alignmentDist;
    [Header("佇列力的比重")]
    public float alignmentWeight;

    [Header("需要聚集的距離")]
    public float cohesionDist;
    [Header("聚集力的比重")]
    public float cohesionWeight;

    private Vector3 velocity;//速度

    private void Awake()
    {
        velocity = Vector3.forward;
    }

    private void Update()
    {
        Vector3 sumForce = Vector3.zero;
        sumForce += Separation() * separationWeight;
        sumForce += Alignment() * alignmentWeight;
        sumForce += Cohesion() * cohesionWeight;
        sumForce += Seek() * speed;

        Vector3 a = sumForce / m;
        velocity += a * Time.deltaTime;

        transform.rotation = Quaternion.Slerp(transform.rotation, Quaternion.LookRotation(velocity), 0.2f);
        transform.Translate(transform.forward * Time.deltaTime, Space.World);
    }

    /// <summary>
    /// 尋找目標
    /// </summary>
    /// <returns></returns>
    private Vector3 Seek()
    {
        Vector3 force = Vector3.zero;
        Vector3 dir = target.position - transform.position;
        force = dir.normalized - transform.forward;
        return force;
    }

    /// <summary>
    /// 得到分離的力
    /// </summary>
    private Vector3 Separation()
    {
        Vector3 separationForce = Vector3.zero;
        GameObject[] objs = GameObject.FindGameObjectsWithTag("UnityFlock");
        foreach (var unity in objs)
        {
            if (unity == gameObject)
            {
                continue;
            }
            if (Vector3.Distance(transform.position, unity.transform.position) <= separationDist)
            {
                Vector3 dir = transform.position - unity.transform.position;
                separationForce += dir.normalized / dir.magnitude;
            }
        }
        return separationForce;
    }

    /// <summary>
    /// 得到佇列的力
    /// </summary>
    private Vector3 Alignment()
    {
        Vector3 alignmentForce = Vector3.zero;
        GameObject[] objs = GameObject.FindGameObjectsWithTag("UnityFlock");
        Vector3 avgDir = Vector3.zero;
        int counter = 0;
        foreach (var unity in objs)
        {
            if (unity == gameObject)
            {
                continue;
            }
            if (Vector3.Distance(transform.position, unity.transform.position) < alignmentDist)
            {
                counter++;
                avgDir += unity.transform.forward;
            }
        }
        avgDir /= counter;
        alignmentForce += (avgDir - transform.forward).normalized;
        return alignmentForce;
    }

    /// <summary>
    /// 聚集
    /// </summary>
    private Vector3 Cohesion()
    {
        Vector3 cohesionForce = Vector3.zero;
        GameObject[] objs = GameObject.FindGameObjectsWithTag("UnityFlock");
        Vector3 avgDir = Vector3.zero;
        int counter = 0;
        foreach (var unity in objs)
        {
            if (unity == gameObject)
            {
                continue;
            }
            if (Vector3.Distance(transform.position, unity.transform.position) < alignmentDist)
            {
                counter++;
                avgDir += unity.transform.position;
            }
        }
        avgDir /= counter;
        cohesionForce += (avgDir - transform.position).normalized;
        return cohesionForce;
    }
}