[ta-edu-course-survival-game] Chapter 2—Performance 101 (2)

Instructions.md

1. Comment out the existing logic (except for _nearestInteractable)
   • We’re going to re-write Interactor using under-performant code
2. Implement the Update method
   • Instead of reacting to GameObjects that invoke the “OnTrigger” methods, we’re going to poll the scene for interactables
3. In Update, declare and initialize a variable called “interactables” using FindObjectsOfType()
   • Like the “GetComponent” methods, Unity has a set of “Find” methods that allow you to search the scene for GameObjects
   • These are generally unsafe because you can’t always predict how many objects will actually be in your scene
4. Add a foreach that loop that iterates over interactables
5. Check if _nearestInteractable is null:
   • If it is, set it to the current interactable
   • Otherwise, check the distance between the _nearestInteractable and the current intractable and update _nearestInteractable if it’s closer
6. Switch to Unity
7. Add 100 interactors and 500 interactables to the scene
   • You can lower these numbers if your computer is having trouble running this scene
   • Let’s pretend that we have a large world with 500 interactables
   • We can also assume that we’ll let actors outside of the player interact with the world, so we’ll create 100 interactors, too
8. Run your game, wait a few seconds, and press the pause button
   • Now our scripts are taking much longer to process

Interactor_0.cs

public class Interactor : MonoBehaviour
{
    private Interactable _nearestInteractable;

    private void OnInteract() => Interact();

    private void Interact()
    {
        if (!_nearestInteractable) return;
        _nearestInteractable.Collect(gameObject);
    }

    private void OnTriggerEnter(Collider other)
    {
        var collectable = other.GetComponent<Interactable>();
        if (!collectable) return;
        _nearestInteractable = collectable;
    }

    private void OnTriggerExit(Collider other)
    {
        var collectable = other.GetComponent<Interactable>();
        if (!collectable || _nearestInteractable != collectable) return;
        _nearestInteractable = null;
    }
}

Interactor_1.cs

using UnityEngine;

public class Interactor : MonoBehaviour
{
    private Interactable _nearestInteractable;

    public OnInteract() => Interact();

    public void Interact()
    {
        if (!_nearestInteractable) return;
        _nearestInteractable.Interact();
    }

    public void Update()
    {
        var interactables = FindObjectsOfType<Interactable>();
        foreach (var interactable in interactables)
        {
            if (_nearestInteractable == null)
            {
                _nearestInteractable = interactable;
            }
            else
            {
                var distToNearest = Vector3.Distance(transform.position, _nearestInteractable.transform.position);
                var distToCurrent = Vector3.Distance(transform.position, interactable.transform.position);

                if (distToCurrent < distToNearest)
                {
                    _nearestInteractable = interactable;
                }
            }
        }
    }
 }