Object Roster

using UnityEngine;
using System.Collections.Generic;
using UnityEngine.Events;

public class ObjectRoster : MonoBehaviour {

    public bool isControlling;

    public float spacing = 1;
    public float angleOffset = 180;

    public float snapDelay = .5f;
    public float snapTimer;

    [SerializeField]
    GameObject _previousGameObject;

    public RosterEvent onChangeObject;

    List<GameObject> gameObjects = new List<GameObject>();

    #region Properties
    protected int CurrentTurretIndex {
        get {
            if(gameObjects.Count == 0) return -1;

            return (int)(NearestAngle / SectionAngle);
        }
    }

    public GameObject CurrentGameObject {
        get {
            return CurrentTurretIndex > -1 ? gameObjects[CurrentTurretIndex] : null;
        }
    }

    public float NearestAngle {
        get { return WrapAngle(Mathf.Round(transform.localEulerAngles.y / SectionAngle) * SectionAngle); }
    }

    public float SectionAngle {
        get { return gameObjects.Count > 0 ? 360f / gameObjects.Count : 0; }
    }
    #endregion

    public virtual void AddGameObject(GameObject gameObject) {
        gameObjects.Add(gameObject);
    }

    protected virtual void Update() {
        if(isControlling) {
            float scroll = Input.GetAxis("Mouse ScrollWheel");

            if(Mathf.Abs(scroll) > float.Epsilon)
                Spin(Input.GetAxis("Mouse ScrollWheel") * 5);
        }

        if(gameObjects.Count > 0) {
            if(snapTimer > 0)
                snapTimer = Mathf.Max(snapTimer - Time.deltaTime, 0);

            if(snapTimer == 0) {
                Quaternion toAngle = Quaternion.Euler(transform.localEulerAngles.x, NearestAngle, transform.localEulerAngles.z);

                transform.rotation = Quaternion.RotateTowards(transform.localRotation, toAngle, Time.deltaTime * Quaternion.Angle(transform.localRotation, toAngle) * Mathf.PI);

                SetCurrentGameObject();
            }

            float angle = SectionAngle;

            for(int i = 0; i < gameObjects.Count; i++) {
                float currentAngle = angle * i;
                Vector3 position = new Vector3(Mathf.Sin(currentAngle * Mathf.Deg2Rad), 0, Mathf.Cos(currentAngle * Mathf.Deg2Rad));

                gameObjects[i].transform.position = transform.position + (transform.rotation * Quaternion.Euler(0, angleOffset, 0) * position * spacing);
            }
        }
    }

    public virtual void Spin(float speed) {
        if(snapTimer == 0)
            SetCurrentGameObject(null);

        snapTimer = snapDelay;

        transform.Rotate(0, speed, 0, Space.Self);
    }

    protected virtual void SetCurrentGameObject() {
        SetCurrentGameObject(CurrentGameObject);
    }
    protected virtual void SetCurrentGameObject(GameObject gameObject) {
        if(_previousGameObject == gameObject) return;

        _previousGameObject = gameObject;

        if(onChangeObject != null) onChangeObject.Invoke(gameObject);
    }

    protected static float WrapAngle(float angle) {
        float value = angle %= 360;

        if(value < 0) angle += 360;

        return angle;
    }

    [System.Serializable]
    public class RosterEvent : UnityEvent<GameObject> { }
}