How to instantiate a prefab one by one in foreach loop

Question

Hello Guys I'm new to unity and I am stuck on a problem. I have to show my prefabs one by one in a slide Show (like a slider in websites) . I have added all my prefabs in a list and I'm trying to show it in a slide show but the problem is all of the prefabs are being displayed at once. I know I have done something wrong in my code. Here's my Code.

 using UnityEngine.SceneManagement;
 using UnityEngine;
 using UnityEngine.UI;
 using System.Collections;
 using System.Collections.Generic;
 
 public class PizzaScript : MonoBehaviour {
 
     public Text header;
     public static List<GameObject> createObjects = new List<GameObject>();
     private static int slideIndex = 1;
 
     // Use this for initialization
     void Start()
     {
         Vector3 startPosition;
         
         Object[] subListObjects = Resources.LoadAll("Prefabs", typeof(GameObject));
 
         foreach(GameObject list in subListObjects)
         {
             GameObject lo = (GameObject)list;
             createObjects.Add(lo);
         }
 
         startPosition = transform.position;
 
         showPrefabs(slideIndex);
     }
     
     // Update is called once per fram
     
     public void OnClickRightArrow()
     {
         plusPrefabs(1);
     }
 
     public void OnClickLeftArrow()
     {
         plusPrefabs(-1);
     }
 
     public void plusPrefabs(int n)
     {
         showPrefabs(slideIndex += n);
     }
 
     public void showPrefabs(int n)
     {
         Vector3 temp = new Vector3(0.34f, 0.074f, 0);
         
         var x = createObjects.Count;
         
         if (n > createObjects.Count)
         {
             slideIndex = 1;
         }
         if (n < 1)
         {
             slideIndex = createObjects.Count;
         }
         
         foreach(GameObject i in createObjects)
         {
             GameObject instance = Instantiate(i, temp, Quaternion.identity);
             i.transform.localScale = new Vector3(10, 10, 10);
         }
 
     }
 
 }

OnClickRightArrow() and OnClickLeftArrow() are my methods that triger when I click the left or Right button

Here is my scene So, that you can get the idea . alt text

Answer 1

Good day.

First, i just saw this:

     foreach(GameObject i in createObjects)
      {
          GameObject instance = Instantiate(i, temp, Quaternion.identity);
          i.transform.localScale = new Vector3(10, 10, 10);
      }

Do you see you are changing the localscale of i (the "prefab"), not the new object called instance ??

And, if you do a foreach, the code will execute all orders for each "i" with no stops. I dont knw what you want to get, but if you dont do any "if" inside the foreach, it will do the code for each i in the list.

If you just want to pause the time between instantiates, use a corutine.

 public void showPrefabs(int n)

  {
      [...]
     StartCorutine (InstantiateObjects());
  }

 Ienumerator InstantiateObjects()
 {
  foreach(GameObject i in createObjects)
          {
              GameObject instance = Instantiate(i, temp, Quaternion.identity);
              i.transform.localScale = new Vector3(10, 10, 10);
              yield return new WaitForSeconds (5);
          }
 }

So now, it will do the code for each "i" , but will wait 5 seconds between each iteration.

Bye!

Answer 2

Hi

Well, your prefabs are all displayed at once, because you instantiate all of them at once. May I propose to you more elegant solution.

From what I see, you want to make a slider which shows different kind of pizzas (your prefabs). Here is the script that spawns all pizzas, then hide them, then show only the one of them, according to what you press.

  public class PizzaScript : MonoBehaviour {
  
      private GameObject[] pizzaArray = new GameObject[0];
      private int pizzaIndex = 0;
      private Vector3 pizzaDisplayPosition = new Vector3(0.34f, 0.074f, 0);
  
      void Start() {
          GameObject[] pizzaPrefabs = Resources.LoadAll("Prefabs", typeof(GameObject));
          pizzaArray = new GameObject[pizzaPrefabs .length];

          for(int i=0;i<pizzaPrefabs .length;i++){
               pizzaArray [i] = Instantiate(pizzaPrefabs[i], pizzaDisplayPosition , Quaternion.identity);
               pizzaArray [i].transform.localScale = new Vector3(10, 10, 10);
               pizzaArray [i].SetActive(false); 
               //SetActive(false) makes this object inactive - it dissapears, cannot be interacted with in any way, but it is still in the scene
          }
  
          plusPrefabs(0);
      }
      
      // Update is called once per fram
      
      public void OnClickRightArrow()
      {
          plusPrefabs(1);
      }
  
      public void OnClickLeftArrow()
      {
          plusPrefabs(-1);
      }
  
      public void plusPrefabs(int n)
      {
          pizzaIndex += n;
          if(pizzaIndex<0) pizzaIndex = pizzaArray.Length-1;
          if(pizzaIndex>=pizzaArray.Length) pizzaIndex = 0;
          
          for(int i=0;i<pizzaPrefabs .length;i++){
               pizzaArray [i].SetActive(false); 
          }
          pizzaArray [pizzaIndex].SetActive(true); 
      }
  
  }

Answer 3

Answer by imraniqbal · Sep 20, 2018 at 06:55 PM

Thanks everyone for your help but I have done it by fixing my Code. I shouldn't use loop there that was the problem I did it by using "if" conditions. Thanks again.

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How to instantiate a prefab one by one in foreach loop

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