Question Help with lists

I need a hand with picking out a random element from a list. I am attempting to spawn prefabs from a list (assigned in the inspector), using a list of Vector3 positions created by several raycasts, I will attach the full script separately as I believe it is not all the relevant.

I am having an issue where the index chosen was out of range (ArgumentOutOfRangeException). I know the random position is the issue, and not the random prefab choice, as the code works if I instantiate at a chosen position.

If I am using lists wrong, please let me know. Any help is appreciated.

Code (CSharp):

1.  void SpawnComponent()
2.     {
3.         for(matchCount = 0; matchCount < numberOfComponents; ++matchCount) //run the loop until the max components has been reached
4.         {
5.             int randomNum = Random.Range(0, spawnPositions.Count);
6.             Vector3 chosenPosition = spawnPositions[randomNum];
7.  
8.             Debug.Log(chosenPosition); //for testing
9.  
10.             GameObject environmentpiece = Instantiate(environmentPrefabs[Random.Range(0,environmentPrefabs.Count)]/*this works*/,
11.             chosenPosition/*this does not*/, Random.rotation);
12.         }
13.     }
14. }

full script

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class CreateEnvironment : MonoBehaviour
6. {
7.     public List<GameObject> environmentPrefabs; //list of prefabs to randomly choose from
8.     public List<Vector3> spawnPositions; //holds positions generated by rays
9.     public GameObject centrePoint, thePlanet;
10.     private Collider planetCollider;
11.     public int numberOfComponents = 5; //max components in the scene
12.     int matchCount, matchRay, rayCount = 6;
13.     public LayerMask whatCanBeHit;
14.    
15.     void Start()
16.     {
17.         planetCollider = thePlanet.GetComponent<Collider>();
18.  
19.         RaycastHit hit;
20.  
21.         for (matchRay = 0; matchRay < rayCount; ++matchRay)
22.         {
23.             if(matchRay == 0)
24.             {
25.                 if(Physics.Raycast(new Vector3(centrePoint.transform.position.x + 8, 0, 0), centrePoint.transform.position, out hit, 10f, whatCanBeHit))
26.                 {
27.                     spawnPositions.Add(hit.point);
28.                 }
29.             }
30.             else
31.             {
32.                 if(Physics.Raycast(new Vector3(centrePoint.transform.position.x - 8, 0, 0), centrePoint.transform.position, out hit, 10f, whatCanBeHit))
33.                 {
34.                     spawnPositions.Add(hit.point);
35.                 }
36.             }
37.         }
38.     }
39.  
40.     void Update()
41.     {
42.         if(matchRay == rayCount)
43.         {
44.             SpawnComponent();
45.             ++matchRay;
46.         }
47.     }
48.  
49.     void SpawnComponent()
50.     {
51.         for(matchCount = 0; matchCount < numberOfComponents; ++matchCount) //run the loop until the max components has been reached
52.         {
53.             int randomNum = Random.Range(0, spawnPositions.Count);
54.             Vector3 chosenPosition = spawnPositions[randomNum];
55.  
56.             Debug.Log(chosenPosition); //for testing
57.  
58.             GameObject environmentpiece = Instantiate(environmentPrefabs[Random.Range(0,environmentPrefabs.Count)]/*this works*/,
59.             chosenPosition/*this does not*/, Random.rotation);
60.         }
61.     }
62. }
63.  

 

You're right, my raycasts are not producing any spawnPositions, so the issue I have now is fixing that. How can I tell the loop I already have to repeat itself if no raycast is produced? The fix that I tried made my unity crash (I made an infinite loop ).

Thanks for suggesting the debugger, also. I use VS code and it seems like I didn't have it installed.

 

Got it working now! Thanks!

 

Excellent! For future reference:

Here are some notes on IndexOutOfRangeException and ArgumentOutOfRangeException:

http://plbm.com/?p=236

Steps to success:
- find which collection it is (critical first step!)
- find out why it has fewer items than you expect
- fix whatever logic is making the indexing value exceed the collection
- remember you might have more than one instance of this script in your scene/prefab