Implementing Event Based Scene Transitions

In this lesson, you will learn how to trigger scene changes using a centralized event channel, effectively decoupling your level triggers from the actual scene-loading logic.

Why Decouple Scene Loading?

When you hard-code SceneManager.LoadScene() inside a specific trigger (like a portal or a finish line), that trigger becomes "coupled" to the loading system. If you want to change how loading works—perhaps by adding a loading screen, a fade animation, or an asynchronous load—you would have to manually update every single trigger in your project.

Instead, we use a ScriptableObject Event Channel. By creating a simple SceneLoadEventChannel, the trigger simply "shouts" into the void that a scene change is requested, and a dedicated SceneManager listener handles the heavy lifting.

Implementation Concept

First, define an event channel that holds a UnityAction<string> (for the scene name).

[CreateAssetMenu(menuName = "Events/Scene Load Event")]
public class SceneLoadEventChannel : ScriptableObject 
{
    public UnityAction<string> OnRequestLoad;
    public void RaiseEvent(string sceneName) => OnRequestLoad?.Invoke(sceneName);
}

Now, your Portal Trigger script doesn't need to know about the SceneManager. It only needs a reference to this ScriptableObject:

public class Portal : MonoBehaviour 
{
    public SceneLoadEventChannel sceneEvent;
    public string targetScene;

    private void OnTriggerEnter(Collider other) 
    {
        sceneEvent.RaiseEvent(targetScene);
    }
}

Finally, create a SceneManagerController that lives in your persistent game logic. It subscribes to the OnRequestLoad event. When it hears the call, it performs the SceneManager.LoadScene logic.

Because the Portal and the SceneManagerController never talk to each other directly, you can swap out the loading system, add transition animations, or change the scene structure without ever touching the individual portal prefabs in your levels. This keeps your project architecture clean, scalable, and easy to debug.

Key Takeaway: By using a ScriptableObject event channel as a bridge, you isolate scene-loading logic from level assets, allowing you to modify your game's transition system globally without editing individual level triggers.