Unity Event System Width Scriptable Objects

Link Demo: Event System With Scriptable Objects (Unity Play)

Blue Voxel Inside Team

1. José Luis Aguilera Luzania
2. Ramón Antonio Sanchez Madrid

Objetives

• Create an easy-to-use and customizable event system in Unity to remove strong reference dependencies between GameObjects.
• Provide a type of generic event that can be specialized for any type of data.

Observer Pattern

Is a behavioral design pattern that lets you define a subscription mechanism to notify multiple objects about any events that happen to the object they’re observing.

Please see: Observer (refactoring.guru) for a full explanation.

Content

By default the package has five predefined events for data types: void, int, float, bool, string.

• VoidEventSO: It is used when it is not necessary to send data to listeners.
• IntEventSO: It is used when it is necessary to send data of type int to listeners.
• FloatEventSO: It is used when it is necessary to send data of type float to listeners.
• BoolEventSO: It is used when it is necessary to send data of type bool to listeners.
• StringEventSO: It is used when it is necessary to send data of type strings to listeners.

How to use it?

Setup listeners

1. First declare the intEvent variable in your script of the type you need.

public IntEventSO intEvent;

2. Create a callback function that will be called every time the event is invoked.

private void OnInt(int value) 
{
	// Do something.
}

3. Register the callback function in the event in the OnEneable function.

private void OnEnable() 
{
	intEvent.AddObserver(OnInt);
}

4. Unregister the callback function in the event in the OnDisable function.

private void OnDisable()
{
	intEvent.RemoveObserver(OnInt);
}

Setup subject

1. First declare the attribute in your script of the type you need.

public IntEventSO intEvent;

2. Use the Invoke(T value) method when you want to notify listeners about something.

// code...
intEvent.Invoke(value);
// more code...

Create the event asset

1. You can create event objects using the "Event SO" submenu in the create menu.
   

2. Assign the asset in the fields of the component that listens or invokes. You can also invoke the event using a button.

Invoke the event using a button.

Assign the assets to a script.

How to create a new type of event?

For this example let's make an event that sends a GameObject as a value when invoked.

1. First we need to create the GameObjectEventSO script.

2. If you want to create your own event with its own data type you must first import the namespace

using Plugins.Event_System_SO.Scripts;

3. Instead of inheriting from MonoBehaviour, we inherit from EventOS and between <> we specify the type of data that will be sent when the event is invoked, in this case GameObject.

public class GameObjectEventSO : EventSO<GameObject>  
{  
}

4. Now we add the attribute CreateAssetMenu where we specify the submenu "Event SO" and the item "GameObject Event".

[CreateAssetMenu(menuName = "Events SO/GameObject Event")]
public class GameObjectEventSO : EventSO<GameObject>  
{  
}

5. Now we can create our asset events that send GameObjects to listeners. We can also use buttons to invoke the events!
   

Images

Dependencies

• TextMeshPro