if ( Transform == null) ?? Empty Transform reference

Question

using UnityEngine; using System.Collections;

 public class Projectile : MonoBehaviour {
  
  private int rotationSpeed = 100;
 
  private int speed = 3;
 
  public Transform target;
  public Transform checkTarget;
  
  private bool ready = false;
  // Use this for initialization
  void Start () {
  }
  
  // Update is called once per frame
  void Update () {
  
  
  
  if (ready){
  transform.localRotation = Quaternion.Slerp(transform.rotation, Quaternion.LookRotation(target.position - transform.position), rotationSpeed * Time.deltaTime);
  transform.Translate(Vector3.forward * Time.deltaTime * speed);
  }
  else{
  Destroy(gameObject);
  }
  
  
  if (target == checkTarget){
  
  }
  else{
  ready = false;
  Destroy(gameObject);
  }
  
  print(target);
 if (target == null){
    Destroy (gameObject);
 }
 
  }
  
  void OnTriggerEnter(Collider other) {
  if (other.CompareTag(&quot;Enemy&quot;)){
  Destroy(gameObject);
  print(&quot;Destroyed&quot;);
  other.SendMessage(&quot;Damage&quot; , 50);
  }
  }
  
  public void SetTarget(Transform tar){
  ready = true;
  target = tar;
  checkTarget = target;
  }
 }

Hello, I want to delete this projectile when the target variable (witch is declared from another object via "SetTarget") is empty, null or however you want to call it.

I know I can delete using many other techniques, like for example checking if its position is the same that the frame before... but i want to know how to do it this way just for the shake of it and I haven't found any post here about it (yes with gameobjects but not with transforms and i haven't been able to adapt it).

Thanks a lot for your help and sorry if this has already been posted, i wasn't able to find it so i hope this one helps someone.

Answer 1

I didn't understand exactly what you wanna do, but supposing that you want to destroy the projectile when its target is dead, just change a little your Update function:

   void Update () {
     // check target existence before anything in Update:
     if (!target){ // if target doesn't exist anymore...
       Destroy(gameObject); // destroy projectile...
       return; // and return from Update to avoid accessing a null target
     }
     // target still exists - do the other stuff:
     if (ready){
       transform.localRotation = Quaternion.Slerp(transform.rotation, Quaternion.LookRotation(target.position - transform.position), rotationSpeed * Time.deltaTime);
       transform.Translate(Vector3.forward * Time.deltaTime * speed);
     } else {
       Destroy(gameObject);
     }
     if (target == checkTarget){
       // do something here
     } else {
       ready = false;
       Destroy(gameObject);
     }
   }
   checkTarget = target;
 }

Notice that the target existence checking was moved to the top of Update: if the target doesn't exist anymore, the projectile suicides and returns from Update to avoid errors in the subsequent instructions.

if ( Transform == null) ?? Empty Transform reference

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