Instantiating without overlapping prefabs

hello all! I am making an endless runner and have one more question. When I am instantiating my prefabs for my endless runner a lot of them are overlapping. How would I go about fixing this? The prefabs are coming out fine, I just cant figure out how to make them not overlap. Would someone know how to go about doing this? I plan on using an array to use a few more prefabs in the long run if that would change someones answer to this question. Thanks!

for (int i = 0; i < 5; i++)
{
Vector2 position = new Vector2(Random.Range(-2f, 2f), Random.Range(-2f, 4f));
Instantiate(Largeb, position, Quaternion.identity);
}

 

In Physics class, Unity has overlap methods as OverlapSphere or OverlapBox to detect other actors in that position.

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class Test : MonoBehaviour {
5.  
6.     public GameObject prefab;
7.     public int numberOfActors = 15;  
8.  
9.     void Update () {
10.  
11.         while (GameObject.FindGameObjectsWithTag(this.prefab.tag).Length < this.numberOfActors)
12.         {
13.  
14.             Vector3 position;
15.            
16.             do
17.             {
18.                
19.                 position = new Vector3(Random.Range(-10f, 10f), 0.5f, Random.Range(-10f, 10f));
20.  
21.             } while (Physics.OverlapSphere(position, 1f).Length > 0);
22.  
23.             (Instantiate(prefab) as GameObject).transform.position = position;
24.            
25.         }
26.    
27.     }
28. }

Use these overlap methods to prevent overlaping.

 

@IsGreen - the idea I agree with, but not the implementation. It was just an example, sure, but since it's public someone will use it and get burned badly.

This is a high potential infinite loop and could backfire very quickly - what if there isn't a valid place to spawn at this particular frame? There needs to be at least an exit condition in the while close.
Time to find a spawn point can also vary wildly (depending on how dense the scene should be).

A more complete (and safe) example would be to use the Overlap* functions to loop through possible positions, add them them to a collection and choose one randomly.

Example:

Code (CSharp):

1. using UnityEngine;
2. using System.Collections.Generic;
3.  
4. public class RunnerSpawnTest : MonoBehaviour
5. {
6.     public GameObject PrefabToSpawn;
7.     public int MaxNumberOfActors = 15;
8.     public float MinX = -2f;
9.     public float MaxX = 2f;
10.     public float MinY = -2f;
11.     public float MaxY = 4f;
12.  
13.     [Range(min: 0.1f, max: 1f)] // clamp Step to some reasonable values
14.     public float Step = 1f;
15.  
16.     private int activeActorCount;
17.     private List<Vector2> spawnablePositions;
18.  
19.     void Start()
20.     {
21.         activeActorCount = 0;
22.         spawnablePositions = new List<Vector2>();
23.     }
24.  
25.     void Update()
26.     {
27.         // untested
28.         // preferably move all this to a separate method and call only under some condition
29.         // f.e. time based
30.         // missing: actors should -- activeActorCount when they're destroyed
31.  
32.         if (activeActorCount >= MaxNumberOfActors)
33.         {
34.             return;
35.         }
36.  
37.         for (float x = MinX; x < MaxX; x += Step)
38.         {
39.             for (float y = MinY; x < MaxY; y += Step)
40.             {
41.                 if (Physics.OverlapSphere(new Vector2(x, y), Step).Length == 0)
42.                 {
43.                     spawnablePositions.Add(new Vector2(x, y));
44.                 }
45.             }
46.         }
47.  
48.         if (spawnablePositions.Count == 0)
49.         {
50.             return; // nowhere to spawn
51.         }
52.  
53.         for (int i = activeActorCount; i <= MaxNumberOfActors; i++)
54.         {
55.             int randomPosition = Random.Range(0, spawnablePositions.Count);
56.             GameObject.Instantiate(PrefabToSpawn, spawnablePositions[randomPosition], Quaternion.identity);
57. spawnablePositions.RemoveAt(randomPosition);
58.         }
59.  
60.         spawnablePositions.Clear();
61.     }
62. }

 

Thanks a lot for your help bud. It really helped me out a lot! Again, I know I keep saying it but I appreciate your persistent help because you have commented on many of my posts!

 

Thanks for your help kally! IT really helped in understanding what I was trying to do. Sorry for the late thank you, I usually thank people the first 10 minutes of their help but this has been a hectic week. I really am appreciating your and the whole unity community in helping me to understand my problems!

 

Speaking of infinite loops, in the 2nd for loop, you check if x < MaxY, I believe you mean if y < MaxY.