Flocks

class Agent : MonoBehaviour
{
    public float alignmentWeight = 1.0f;
    public float cohesionWeight = 1.0f;
    public float seperationWeight = 1.0f;

    public float speed = 3.0f;

    public Vector3 Direction { get; private set; }

    private void Start()
    {
        Direction = UnityEngine.Random.insideUnitSphere;
        FlocksManager.AddAgent(this);
    }

    private void Update()
    {
        List<Agent> _neighbors = FlocksManager.GetNeighbors(this);

        //Calculate my final direction
        Direction = Alignment(ref _neighbors) * alignmentWeight + Separation(ref _neighbors) * seperationWeight + Cohesion(ref _neighbors) * cohesionWeight;

        //Make it a radius of 1
        Direction.Normalize();
        transform.position += Direction * speed * Time.deltaTime;
    }

    Vector3 Alignment(ref List<Agent> _neighbors)
    {
        Vector3 alignment = Vector3.zero;
        for(int i = 0; i < _neighbors.Count; ++i)
        {
            alignment += _neighbors[i].Direction;
        }

        return alignment / (float)_neighbors.Count;
    }

    Vector3 Cohesion(ref List<Agent> _neighbors)
    {
        Vector3 cohesion = Vector3.zero;
        for (int i = 0; i < _neighbors.Count; ++i)
        {
            cohesion += _neighbors[i].transform.position;
        }

        return cohesion / (float)_neighbors.Count;
    }


    Vector3 Separation(ref List<Agent> _neighbors)
    {
        Vector3 cohesion = Vector3.zero;
        for (int i = 0; i < _neighbors.Count; ++i)
        {
            cohesion -= _neighbors[i].transform.position;
        }

        return cohesion / (float)_neighbors.Count;
    }
}

static class FlocksManager
{
    static float neighborRadius = 3.0f;
    static List<Agent> agents = new List<Agent>();

    public static void AddAgent(Agent _agent)
    {
        agents.Add(_agent);
    }

    public static void RemoveAgent(Agent _agent)
    {
        agents.Remove(_agent);
    }

    public static List<Agent> GetNeighbors(Agent _agent)
    {
        List<Agent> neighbors = new List<Agent>();

        for(int i = 0; i < agents.Count; ++i)
        {
            if(Vector3.SqrMagnitude(agents[i].transform.position - _agent.transform.position) < neighborRadius * neighborRadius)
            {
                neighbors.Add(agents[i]);
            }
        }

        return neighbors;
    }
}