A simple EventBus library in C# for Unity
// Create a unique class for each type of event
class PlayerJumpEvent : EventBase {
public Vector3 jumpPosition;
public PlayerJumpEvent(Vector3 pos) {
jumpPosition = pos;
}
}
private void TestMethod() {
IEventBus eventBus = new EventBus();
eventBus.Subscribe<PlayerJumpEvent>(OnPlayerJump);
eventBus.Publish(new PlayerJumpEvent(new Vector3(1,1,0)));// OnPlayerJump will be invoked
eventBus.Unsubscribe(OnPlayerJump);
}
private void OnPlayerJump(PlayerJumpEvent event) {
Console.WriteLine(playerJumpEvent.newPosition);
}Each event subscription must be removed by calling EventBus.Unsubscribe(actionDelegate). This means in order to unsubscribe from an event, you must keep a reference to your action delegate, or use a function reference. Make sure to remove a subscription whenever it's script is going to be destroyed to avoid memory leaks.
First, we can create a global instance of our EventBus in a global GameController or similarly scoped object.
using GameEventBus;
public class GameController : MonoBehaviour {
public static EventBus Bus = new EventBus();
}Lets say we have a Player game object and script that responds when a collider with the tag "bullet" collides with it. When your Player collides with a bullet, you can publish a BulletCollision event, with information about the collision.
public class Player : Monobehaviour {
void OnCollisionEnter(Collision collision) {
if(collision.gameObject.tag == "bullet") {
GameController.Bus.Publish<BulletCollision>(new BulletCollision(collision));
}
}
}
using GameEventBus.Events;
public class BulletCollisionEvent : EventBase {
public Collision collision;
public BulletCollisionEvent(Collision collision) {
this.collision = collision;
}
}All of our scripts that subscribe to the BulletCollision event will be notified whenever our Player is hit with a Bullet
public class Hud : Monobehaviour {
void Start() {
GameController.Bus.Subscribe<BulletCollisionEvent>(OnBulletCollision);
}
void OnBulletCollision(BulletCollisionEvent event) {
Debug.Log("Our HUD was notified of a bullet collision!")
}
void OnDestroy() {
GameController.Bus.Unsubscribe(OnBulletCollision);
}
}