Index out of range when trying to spawn objects using spawn location list

Questions & Answers
1

Hello everyone, I’m new to Unity and C# I require a detailed help.

I’m currently creating my first self project where 3 platforms that the player shouldn’t go and 1 platform that s/he should. These platforms are created around the player on specific positions (up, down, left, right). So I try to spawn these platforms on 4 random locations using a spawner location list. My aim is to create 3 false platforms on random locations without overlapping each other, and creating 1 true platform overlapping no other platform. My code to spawn platforms are in Spawner() function. But if I try to run my game, i get an error saying my randomSpawnerIndex is out of range on falsePlatform2:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;

public class GameManager : MonoBehaviour
{
    public PlayerController movement;

    public Transform player;
    public Transform playerPlatform;
    public Transform cameraPosition;

    public GameObject truePlatform;
    public GameObject falsePlatform;
    public GameObject Spawn1;
    public GameObject Spawn2;
    public GameObject Spawn3;
    public GameObject Spawn4;

    private Vector3 platformYOffset;
    private Vector3 cameraYOffset;

    bool gameHasEnded = false;
    public float restartDelay = 1f;

    void Start()
    {
        Spawner();
    }


    

    public void EndGame()
    {
        if(gameHasEnded == false)
        {
            gameHasEnded = true;
            Invoke("Restart", restartDelay);
        }
    }

    
    //RESTART
    
    void Restart()
    {
        SceneManager.LoadScene(SceneManager.GetActiveScene().name);
    }


    


    public void OnTrueMove()
    {
        platformYOffset = new Vector3(0, (float)0.5, 0);
        GameObject[] falsePlatforms = GameObject.FindGameObjectsWithTag("FalsePlatform");
        foreach (GameObject falseOne in falsePlatforms)
        {
            Destroy(falseOne);
        }

        truePlatform.GetComponent<Transform>().position = new Vector3(0, -3, 0);

        platformYOffset = new Vector3(0, (float)0.5, 0);
        cameraYOffset = new Vector3(0, 8, 0);

        playerPlatform.position = player.position - platformYOffset;
        cameraPosition.position = player.position + cameraYOffset;
        Spawner();
    }

    
    void Spawner()
    {
        List<Vector3> spawnLocs = new List<Vector3>();
        spawnLocs.Add(Spawn1.transform.position);
        spawnLocs.Add(Spawn2.transform.position);
        spawnLocs.Add(Spawn3.transform.position);
        spawnLocs.Add(Spawn4.transform.position);

        Debug.Log(spawnLocs.Count);

        platformYOffset = new Vector3(0, (float)0.5, 0);

        int randomSpawnerIndex = Random.Range(0, spawnLocs.Count);

        GameObject instantiatedFalse1 = Instantiate(falsePlatform, spawnLocs[randomSpawnerIndex] - platformYOffset, Quaternion.identity);
        spawnLocs.RemoveAt(randomSpawnerIndex);
        Debug.Log(spawnLocs.Count);
        GameObject instantiatedFalse2 = Instantiate(falsePlatform, spawnLocs[randomSpawnerIndex] - platformYOffset, Quaternion.identity);
        spawnLocs.RemoveAt(randomSpawnerIndex);
        Debug.Log(spawnLocs.Count);
        GameObject instantiatedFalse3 = Instantiate(falsePlatform, spawnLocs[randomSpawnerIndex] - platformYOffset, Quaternion.identity);
        spawnLocs.RemoveAt(randomSpawnerIndex);
        Debug.Log(spawnLocs.Count);

        GameObject instantiatedTrue = Instantiate(truePlatform, spawnLocs[randomSpawnerIndex] - platformYOffset, Quaternion.identity);
        spawnLocs.RemoveAt(randomSpawnerIndex);
    }
}

I tried to create the true platform using the last element of the spawnLocs list.

I look forward to your help and any suggestions that make my very basic game mechanic become real.

2

You need to update randomSpawnerIndex after removing elements from the spawnLocs list.

I highly advise you to put the spawn logic in a function

void Spawner()
{
    List<Vector3> spawnLocs = new List<Vector3>();
    spawnLocs.Add(Spawn1.transform.position);
    spawnLocs.Add(Spawn2.transform.position);
    spawnLocs.Add(Spawn3.transform.position);
    spawnLocs.Add(Spawn4.transform.position);

    platformYOffset = new Vector3(0, 0.5f, 0);
    SpawnPlatform(spawnLocs, falsePlatform, platformYOffset);
    SpawnPlatform(spawnLocs, falsePlatform, platformYOffset);
    SpawnPlatform(spawnLocs, falsePlatform, platformYOffset);
    SpawnPlatform(spawnLocs, truePlatform, platformYOffset);
}

void SpawnPlatform(List<Vector3> spawnLocs, GameObject prefab, Vector3 offset)
{
    if(spawnLocs.Count == 0)
    {
        Debug.LogError("No spawn location available");
        return;
    }
    int randomSpawnerIndex = Random.Range(0, spawnLocs.Count);

    GameObject instance = Instantiate(prefab, spawnLocs[randomSpawnerIndex] - offset, Quaternion.identity);
    spawnLocs.RemoveAt(randomSpawnerIndex);
}