More Efficient Way to Find Active GameObject

Question

[This is coding using C#]

I've gotten a game to work, but I am using quite horrendous code to do so. I have a spawning script that checks if a simple 2D gameobject exists in the scene, and spawns one if nothing is there. here is that script:

 //Manages the spawning of the NPC gameObjects the player interacts with
 //Determines if anything is already is on the board, if not it spawns
 // a random one out of the available pool (similar to RandomBG.cs)
 
 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class SpawnManager : MonoBehaviour {
 
     private GameObject activeNPC; //The active NPC gameObject
     private GameObject nextNPC; //Next NPC gameObject to be spawned
     public GameObject[] availableNPCPool = new GameObject[9]; //Pool of the usable NPC gameobjects
 
     // Use this for initialization
     void Start ()
     {
         SpawnNPC(); //For initial spawn
     }
     
     // Update is called once per frame
     void Update ()
     {
         SpawnNPC(); //For recurring spawns
     }
 
     void SpawnNPC()
     {
         //Spawn gameObject if nothing is in the scene
         if (!activeNPC)
         {
             int randomValue = (int)(Random.Range(0, 8.9f)); //Picks a random number between 0 (inclusive) and 8; int cast is so arrary can use it
             nextNPC = availableNPCPool[randomValue]; //Sets the next NPC to spawn randomly from pool
             Debug.Log("Shape is " + randomValue);
             Instantiate(nextNPC); //Spawns gameObject with its prefab settings (i.e Transform)
         }
 
         activeNPC = Object.FindObjectOfType<MoveNPC>().gameObject; //Finds the game object with the MoveNPC script attached
     }
 }

As you can see, I am using FindObjectsOfType in Update! I know this is awful and I would use tags, but I have three different sets of tags for all nine possible spawnable objects (I use the tags for another test in another script).

My question is: would it be better to test using an if statement to test if a gameobject with either of the three tags exists, or is this fine due to the game requiring so little resources (it's literally a matching game of shapes, all basic 2D sprites)?

I know this is a weird question, but I thank all for the help regardless.

Answer 1

What exactly does your MoveNPC script do? If I understand correctly, the MoveNPC script will destroy the NPC at some point, at which point you want to spawn another random NPC.

The way I would approach this is using events, and then having the currently active MoveNPC script 'inform' anyone interested that it has destroyed itself.

MoveNPC:

 public event Action OnNPCDestroyed;
 // Called just before the gameObject is destroyed
 private void OnDestroy()
 {
     if(OnNPCDestroyed != null)
          OnNPCDestroyed(); // Will call any functions subscribed to the OnNPCDestroyed delegate when this gameObject is destroyed. 
 }

SpawnManager:

  void SpawnNPC()
  {
          int randomValue = (int)(Random.Range(0, 8.9f)); //Picks a random number between 0 (inclusive) and 8; int cast is so arrary can use it
          nextNPC = availableNPCPool[randomValue]; //Sets the next NPC to spawn randomly from pool
          Debug.Log("Shape is " + randomValue);
          GameObject npcGO =  Instantiate(nextNPC) as GameObject; //Spawns gameObject with its prefab settings (i.e Transform)
          npcGO.GetComponent<MoveNPC>().OnNPCDestroyed += SpawnNPC; // When the last NPC was destroyed, call this functions

 }

Note that I am not checking if the activeNPC gameobject is not null because when OnDestroy is called by unity, the gameobject has not yet been destroyed. You should also note that actions need to be unsubscribed. npcGO.GetComponent<MoveNPC>().OnNPCDestroyed -= SpawnNPC; The only reason I have not included this is because the gameobject holding the MoveNPC script is destroyed, so the garbage collector should clean it all up.

Answer 2

Answer by Commoble · May 29, 2017 at 09:48 PM

You can avoid searching for objects during runtime by keeping references to your objects in variables. You can do this by using something along the lines of:

 if (this.activeNPC == null)
 {
     this.activeNPC = Instantiate(nextNPC);
 }

Instantiate returns a reference to the object instantiated; if you store this reference in a variable, you don't have to use Find-like searching to find your instantiated object.

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LetsBeChillx · Jun 03, 2017 at 06:59 PM 0

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I am already using that code lol check lines 30 to 35. What I am doing the check is to see whether the exists an NPC in the scene already, so using references would not work here.

More Efficient Way to Find Active GameObject

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