public struct Boid : IComponentData
{
    public float MovementSpeed;
    public float TurnSpeed;
    public float Size;

    public float4 Velocity;
    public float4 AngularVelocity;

    public BoidType Type;
}

public partial struct SeparationJob : IJobEntity
{
    [WriteOnly] public NativeArray<float4> Separation;

    [ReadOnly] public NativeParallelMultiHashMap<int2, Entity> BoidCells;
    [ReadOnly] public ComponentLookup<LocalTransform> TransformLookup;

    public float AvoidFactor;

    public void Execute(Entity e, int index, in LocalTransform transform, in Boid boid)
    {
        var delta = float4.zero;

        var key = (int3)(transform.Position * ChunkSize);
        key.y = 0;

        var neighbors = BoidCells.GetValuesForKey(key.xz);

        while (neighbors.MoveNext())
        {
            if (neighbors.Current.Equals(e)) continue;

            var other = TransformLookup[neighbors.Current];

            if (math.distancesq(transform.Position, other.Position) < boid.Size * boid.Size)
            {
                delta += transform.Position.xyzz - other.Position.xyzz;
            }
        }

        Separation[index] = delta * AvoidFactor;
    }
}

public partial struct MoveJob : IJobEntity
{
    [ReadOnly] public NativeArray<float4> Separation;
    [ReadOnly] public NativeArray<float4> Alignment;
    [ReadOnly] public NativeArray<float4> Cohesion;

    public float DeltaTime;

    public void Execute(ref LocalTransform transform, ref Boid boid)
    {
        var velocity =
            boid.Velocity +
            (Separation[index] + Alignment[index] + Cohesion[index]) * DeltaTime;

        boid.Velocity = velocity;

        transform.Position += boid.Velocity.xyz * DeltaTime;
    }
}