Architecting Robust Collision Event Managers

In this lesson, you will learn how to shift collision logic away from individual GameObjects and into a centralized manager to keep your codebase clean and scalable.

The Problem with "Spaghetti" Collisions

Up until now, you have likely placed OnCollisionEnter or OnTriggerEnter directly inside your player, enemy, or item scripts. While this works for simple prototypes, it quickly becomes messy. If you have fifty different "pickable" objects, you end up with fifty identical scripts handling physics logic. If you decide to change how an item is collected, you have to hunt down and update every single one of those files.

The Centralized Manager Pattern

Instead of letting every object decide how to react to a collision, we can create a single CollisionManager. This manager acts as a central hub that intercepts collision data and distributes it to the appropriate systems.

Think of it like a traffic controller: your game objects simply "report" that a collision happened, and the manager decides what to do based on the object's identity or properties.

A Simple Implementation

To start, create a script that any object can use to "check-in" with the manager.

public class CollisionEventDispatcher : MonoBehaviour 
{
    public void OnCollisionEnter(Collision collision) 
    {
        // Instead of writing logic here, we notify the manager
        CollisionManager.Instance.HandleCollision(gameObject, collision);
    }
}

The CollisionManager then houses the actual business logic:

public class CollisionManager : MonoBehaviour 
{
    public static CollisionManager Instance;

    public void HandleCollision(GameObject source, Collision collision) 
    {
        if (collision.gameObject.CompareTag("Player")) 
        {
            // Centralized logic: What happens when anything hits the player?
        }
    }
}

Why This Matters

By decoupling the physics trigger from the logic, you gain two major benefits:

1. Maintainability: You only have one place to change the rules of your physics interactions.
2. Readability: Your gameplay scripts stay focused on their specific roles (movement, stats, etc.) rather than being cluttered with boilerplate collision code.

As your game grows, you can even expand this manager to filter collisions by layer or ignore specific interactions, keeping your physics pipeline predictable.

Key Takeaway: Centralizing your collision logic into a single manager separates the "what was hit" from the "how to react," creating a modular and maintainable architecture.