[ta-edu-course-survival-game] Chapter 2 — MonoBehaviours & GameObjects

Instructions.md

• Create Interactor.cs
  • We want to let the Player interact with the environment
  • Or in other words, we want the Player to be an interactor of the environment
• Create Interactable.cs
  • Interactors needs something to interact with, so let's define a new component called "Interactable"
• Open Interactable.cs
• Implement a public method called Interact()
  • The idea here is that Interactors will call this method
• Add a Debug.Log() statement to Interact()
  • Debug.Log("I've been interacted with!", gameObject)
  • Let's log something to the console to verify that our behavior works when we get it all set up in the editor
• Open Interactor.cs
• Implement a public method called OnInteract()
  • We need a way for the player initiate an interaction
  • This method will called by Unity's input system, which is outside the scope of this course
• Add a private field called _nearestInteractable
  • For our implementation, we're gonna have the interactor keep track of the nearest interactable at all times
• Add a call to _nearestInteractable.Interact() to OnInteract()
  • So all OnInteract() has to do is call Interact on the nearest interactable
• Implement the Update() method
  • Update is method that's special to MonoBehaviours, just like Start
  • We're going to cover these special methods in future section
  • For now, just know that Update gets called once a frame
• Implement the logic to set _nearestInteractable
  • The implementation isn't important here
  • We've actually written an unoptimized version of this code that we'll revisit later
• Switch back to Unity
• Drag the Interactor component onto the Player GameObject
• Add a cube in the scene called "Interactable"
• Drag the Interactable component onto the Interactable GameObject
• Run the scene and demonstrate the working behavior

Interactable.cs

using UnityEngine;

public class Interactable : MonoBehaviour
{
  public void Interact()
  {
    Debug.Log("I've been interacted with!", this);
  }
}

Interactor.cs

using UnityEngine;

public class Interactor : MonoBehaviour
{
  private float _minimumDistance = 3;
  private Interactable _nearestInteractable;
  
  public void OnInteract()
  {
    _nearestInteractable?.Interact();
  }
  
  private void Update()
  {
    _nearestInteractalbe = null;
    foreach (interactable in FindObjectsOfType<Interactable>())
    {
      if (Distance(interactable.transform) > _minimumDistance) continue;
      if (_nearestInteractable == null || Distance(interactable.transform) < Distance(_nearestInteractable.transform))
      {
        _nearestInteractable = interactable;
      }
    }
  }
  
  public float Distance(Transform other) => Vector3.Distance(transform.position, other.position)
}