Unity foundation 1 - event execution sequence, custom events

Sequence of events

stay unity in , We control the behavior of objects by adding scripts , It is very important to understand the sequence of events in the script . For details, see Official documents

The most commonly used life cycle functions are ：
Some code snippets come from B Stand on the teacher's 3DRPG Course Of playercontroller.cs and mousemanager.cs
Awake
for example , Get reference of component

	void Awake()
    {
    
        agent = GetComponent<NavMeshAgent>();
        anim = GetComponent<Animator>();
        characterStats = GetComponent<CharacterStats>();
        stopDistance = agent.stoppingDistance;
    }

Or bind the current script to the game object , Do not delete when marked to switch scenes

	protected override void Awake()
    {
    
        base.Awake();
        DontDestroyOnLoad(this);
    }

OnEnable
Bind handlers for some events

	void OnEnable()
    {
    
        MouseManager.Instance.OnMouseClick += MoveToTarget;
        MouseManager.Instance.OnEnemyClick += EventAttack;
        GameManager.Instance.RegisterPlayer(characterStats);
    }

Update
Handle the input of the game 、 State switching, etc

	void Update()
    {
    
        isDead = characterStats.CurrentHealth == 0;
        if (isDead)
        {
    
            GameManager.Instance.NotifyObservers();
        }
        SwitchAnimation();
        lastAttackTime -= Time.deltaTime;
    }

OnDisable
Unregister the handler for some events

	void OnDisable()
    {
    
        MouseManager.Instance.OnMouseClick -= MoveToTarget;
        MouseManager.Instance.OnEnemyClick -= EventAttack;
    }

OnDestroy

	protected virtual void OnDestory()
    {
    
        if (instance == this)
        {
    
            instance = null;
        }
    }

FixUpdate
For physical state update , The fixed frame interval makes the physical effect more realistic
LateUpdate
For camera following , Only the last frame needs to update the position of the camera , The previous few frames can only update the information such as the position of the object .

Custom events

Sometimes we need to be outside the life cycle events , Custom events , for example , When replacing the mouse with an image , Judge the clicked items by emitting rays from the image position , Define your own logic for handling mouse click events , Event name required OnMouseClick And the parameter types required by the event handler Vector3

Law 1 ： Inherit UnityEvent<T> Generic classes , Define your own event class , The advantage is that the editor can be in inspector The window is adding an event handler , like UI Button The click event of the button is the same

	using UnityEngine.Events;

	[Serializable]
	public class EventVector3 : UnityEvent<Vector3> {
     }

Declare custom events

public class MouseManager : Singleton<MouseManager>
{
    
    RaycastHit hitInfo;
    public EventVector3 OnMouseClick;
    //  Or use it directly  UnityEvent
    // public UnityEvent OnGameFinish;
    ...
}

Law two ： Use Csharp Commission of Action Define your own events , The advantage is easy to use

public class MouseManager : Singleton<MouseManager>
{
    
    RaycastHit hitInfo;
    // public EventVector3 OnMouseClick;
    public event Action<Vector3> OnMouseClick;
    public event Action<GameObject> OnEnemyClick;
	...
}

---

Bind and remove event handlers

	void OnEnable()
    {
    
        MouseManager.Instance.OnMouseClick += MoveToTarget;
        MouseManager.Instance.OnEnemyClick += EventAttack;
        GameManager.Instance.RegisterPlayer(characterStats);
    }
    void OnDisable()
    {
    
        MouseManager.Instance.OnMouseClick -= MoveToTarget;
        MouseManager.Instance.OnEnemyClick -= EventAttack;
    }

Call event

	void MouseControl()
    {
    
        if (Input.GetMouseButtonDown(0) && hitInfo.collider != null)
        {
    
            if (hitInfo.collider.gameObject.CompareTag("Ground"))
            {
    
                OnMouseClick?.Invoke(hitInfo.point);
            }
            else if (hitInfo.collider.gameObject.CompareTag("Enemy"))
            {
    
                OnEnemyClick?.Invoke(hitInfo.collider.gameObject);
            }
            else if (hitInfo.collider.gameObject.CompareTag("Attackable"))
            {
    
                OnEnemyClick?.Invoke(hitInfo.collider.gameObject);
            }
            else if (hitInfo.collider.gameObject.CompareTag("Protal"))
            {
    
                OnMouseClick?.Invoke(hitInfo.point);
            }
        }
    }

The rest of the code , Is in the update Medium emission ray

	void Update()
    {
    
        SetCursorTexture();
        MouseControl();
    }

    void SetCursorTexture()
    {
    
        Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
        if (Physics.Raycast(ray, out hitInfo))
        {
    
            //  Toggle mouse mapping 
            switch (hitInfo.collider.gameObject.tag)
            {
    
                case "Ground":
                    Cursor.SetCursor(target, new Vector2(16, 16), CursorMode.Auto);
                    break;
                case "Enemy":
                    Cursor.SetCursor(attack, new Vector2(16, 16), CursorMode.Auto);
                    break;
                case "Protal":
                    Cursor.SetCursor(doorway, new Vector2(16, 16), CursorMode.Auto);
                    break;
                default:
                    Cursor.SetCursor(arrow, new Vector2(16, 16), CursorMode.Auto);
                    break;
            }
        }
    }