Can Someone please explain how to fix this error, I've seen people use random but it won't let me

Question

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class SpawnManager : MonoBehaviour
 {
     public float SpawnRangeX = 9.7f;
     public float SpawnPosY = 4f;
     public GameObject[] EnemyPrefabs;
     public float SpawnDelay = Random.Range(0, 1);
     public int RandomNum;
     public Vector3 SpawnLocation;
 
     // Start is called before the first frame update
     void Start()
     {
         SpawnEnemies();
     }
 
     // Update is called once per frame
     void Update()
     {
         RandomNum = Random.Range(0,EnemyPrefabs.Length);
         SpawnLocation = new Vector3(Random.Range(SpawnRangeX, -SpawnRangeX), 0, SpawnPosY);
     }
 
     private void SpawnEnemies()
     {
         
         Instantiate(EnemyPrefabs[RandomNum], SpawnLocation, EnemyPrefabs[RandomNum].transform.rotation);
 
     }
     
 }
 ![alt text][1]

[1]: /storage/temp/197603-error.png

Answer 1

Answer by gliiv_ · Jun 21 at 06:57 PM

@qarallax is correct in moving the random functions from Update() into Start(), as it would yield better performance, but the issue lies in the constructor for your SpawnDelay variable. Unity doesn't like it when you try to give a freshly constructed variable a random range, so you'll have to do it in Start() or Awake(). I've applied the relevant fixes to your code and recommend you compare it to the code you wrote to get better context, but here it is below!

     using System.Collections;
     using System.Collections.Generic;
     using UnityEngine;
     
     public class SpawnManager : MonoBehaviour 
     { 
         public float SpawnRangeX = 9.7f;
         public float SpawnPosY = 4f;
         public GameObject[] EnemyPrefabs;
         public float SpawnDelay;
         public int RandomNum;
         public Vector3 SpawnLocation;
     
          // Start is called before the first frame update
         void Start()
         {
             SpawnEnemies();
             RandomNum = Random.Range(0,EnemyPrefabs.Length);
             SpawnLocation = new Vector3(Random.Range(SpawnRangeX, -SpawnRangeX), 0, SpawnPosY);
             SpawnDelay = Random.Range(0, 1);
         }
         // Update is called once per frame
         void Update()
         {
     
         }
         private void SpawnEnemies()
         {        
             Instantiate(EnemyPrefabs[RandomNum], SpawnLocation, EnemyPrefabs[RandomNum].transform.rotation);
         }
     }

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SgtHobbs · Jun 21 at 07:03 PM 0

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it's still saying the same error as I linked to my question

gliiv_ SgtHobbs · Jun 21 at 08:06 PM 0

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That is incredibly strange. I've tested this code in my own Unity project to make sure I wasn't going crazy, and I'm not getting the error in question. Are you sure you have modified the code to correct the error / saved the file? Not trying to be mean (I forget to save more often than I care to admit myself lol) and the error text specifically gives us the reason for the error, in that you aren't allowed to use Random.Range in a constructor. If you could post the code you have currently here (after applying the requisite fixes, I wouldn't expect you to post literally the same exact code) and we can take a look and see where the breakdown is.

qarallax gliiv_ · Jun 22 at 12:20 PM 1

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Yeah its strange. As @gliiv_ say the line causing the error should be this:`public float SpawnDelay = Random.Range(0, 1);`

Bonfire-Boy SgtHobbs · Jun 23 at 01:54 PM 1

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This is the correct answer (the error message is telling us exactly what you've done wrong), so please don't give up on it.

If you have made the change @gliiv has shown you, removing the call to Random.Range() from the field initialiser, and you're still getting the same error, then IMO you've probably made the same mistake somewhere else.

Bunny83 · Jun 22 at 02:43 PM 1

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You shouldn't call SpawnEnemies before you roll your random numbers... That doesn't make much sense. However the issue indeed is the usage of Random.Range inside the field initializer, well, just as the error tells you ^^.

Though having a single script that only spawns a single enemy probably doesn't make much sense. The rolling of the random numbers probably should be inside the SpawnEnemies method before the Instantiate call. That way you can spawn a new random enemy by simply calling that method again. How, when and how often is of course up to the OP. Though you usually don't want to spawn one new enemy every frame.

Answer 2

Answer by qarallax · Jun 21 at 05:35 PM

Try to put "RandomNum = Random.Range(0,EnemyPrefabs.Length);" in the start method instead of the update method. And make sure to put it before you call the spawnEnemies void. Right now you are changing RandomNum every frame.

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SgtHobbs · Jun 21 at 05:37 PM 0

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The same error still shows up

qarallax SgtHobbs · Jun 21 at 05:39 PM 0

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Actually you should do that with all the lines in the update method.

SgtHobbs qarallax · Jun 21 at 06:16 PM 0

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Still no luck, been hours and I have no clue. I'm a beginner but damn

Bonfire-Boy · Jun 23 at 01:57 PM 1

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This answer is incorrect. Having that call in Update() will not cause the error shown.

As other answers state, it is the call to Random.Range in the field initialiser that is the issue.

Answer 3

Answer by Lennyy96 · Jun 21 at 06:50 PM

Maybe it‘s because you first call spawn enemies and then you set randomNum.

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SgtHobbs · Jun 21 at 07:04 PM 0

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I've changed it as said by other people but it still doesn't work.

Can Someone please explain how to fix this error, I've seen people use random but it won't let me

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