How to spawn at random times?

I'm working on the Challenge 2 - Play Fetch - Unity Learn On the 1st bonus question it says spawn balls at random times between 3 and 5 seconds. I have tried putting the Random.Range in the float and get error messages every time. So I tried in the start method and get no error messages.

Code (CSharp):

1.  
2. public class SpawnManagerX : MonoBehaviour
3. {
4.     public GameObject[] ballPrefabs;
5.  
6.     private float spawnLimitXLeft = -22;
7.     private float spawnLimitXRight = 7;
8.     private float spawnPosY = 30;
9.  
10.     private float startDelay = 1.0f;
11.     private float spawnInterval;
12.  
13.     // Start is called before the first frame update
14.     void Start()
15.     {
16.         spawnInterval = Random.Range(2, 6);
17.         InvokeRepeating("SpawnRandomBall", startDelay, spawnInterval);
18.     }
19.  
20.     // Spawn random ball at random x position at top of play area
21.     void SpawnRandomBall ()
22.     {
23.         int ballIndex = Random.Range(0, ballPrefabs.Length);
24.  
25.         // Generate random ball index and random spawn position
26.         Vector3 spawnPos = new Vector3(Random.Range(spawnLimitXLeft, spawnLimitXRight), spawnPosY, 0);
27.  
28.         // instantiate ball at random spawn location
29.         Instantiate(ballPrefabs[ballIndex], spawnPos, ballPrefabs[ballIndex].transform.rotation);
30.     }
31.  
32. }
33.  

But it spawns balls around every 4 seconds at same rate all time.
I have put the spawnInterval = Random.Range(2, 6); line in the spawnRandomBall method as it says to in the hints, but it doesn't keep spawning balls.

Also how can I do the last bonus task of only allowing the player to spawn more dogs after certain amount of time has passed?

 

copy the < spawnInterval = Random.Range(2, 6);> and paste it in a void update.
so that its value can keep changing
But keep it in start also as start is called before update.

 

Hello, have you solved the problem? I have the same problem

 

Please share your code with Code Tags and paste the error that you are receiving.

 

Thank you for your reply. My code is in the following picture. The task requires a random time between 3 and 5 seconds to generate a ball. This is the method I tried, but it seems incorrect. I'm a beginner. I hope you can teach me how to solve this problem. Thank you!!！

 

Please post with code tags as suggested, just like the first post in this thread, and not screenshots. But at any rate, is this code working? Why does it seem incorrect?

 

After the code is run, the generation time of each ball is not random. It can only randomly select a number in 3-5 seconds, and then generate a ball at that time interval each time. This does not meet the requirements of the task.

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class SpawnManagerX : MonoBehaviour
6. {
7.     public GameObject[] ballPrefabs;
8.  
9.     private float spawnLimitXLeft = -22;
10.     private float spawnLimitXRight = 7;
11.     private float spawnPosY = 30;
12.  
13.     private float startDelay = 1.0f;
14.     private float spawnInterval;
15.  
16.     // Start is called before the first frame update
17.     void Start()
18.     {
19.         float spawnInterval = Random.Range(3, 5);
20.         InvokeRepeating("SpawnRandomBall", startDelay, spawnInterval);
21.     }
22.  
23.     // Spawn random ball at random x position at top of play area
24.     void SpawnRandomBall ()
25.     {
26.         //Randomly generated ball color
27.         int ballIndex = Random.Range(0, ballPrefabs.Length);
28.         spawnInterval = Random.Range(3, 5);
29.  
30.         // Generate random ball index and random spawn position
31.         Vector3 spawnPos = new Vector3(Random.Range(spawnLimitXLeft, spawnLimitXRight), spawnPosY, 0);
32.  
33.         // instantiate ball at random spawn location
34.         Instantiate(ballPrefabs[ballIndex], spawnPos, ballPrefabs[ballIndex].transform.rotation);
35.     }
36. }

 

After the code is run, the generation time of each ball is not random. It can only randomly select a number in 3-5 seconds, and then generate a ball at that time interval each time. This does not meet the requirements of the task.

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class SpawnManagerX : MonoBehaviour
6. {
7.     public GameObject[] ballPrefabs;
8.  
9.     private float spawnLimitXLeft = -22;
10.     private float spawnLimitXRight = 7;
11.     private float spawnPosY = 30;
12.  
13.     private float startDelay = 1.0f;
14.     private float spawnInterval;
15.  
16.     // Start is called before the first frame update
17.     void Start()
18.     {
19.         float spawnInterval = Random.Range(3, 5);
20.         InvokeRepeating("SpawnRandomBall", startDelay, spawnInterval);
21.     }
22.  
23.     // Spawn random ball at random x position at top of play area
24.     void SpawnRandomBall ()
25.     {
26.         //Randomly generated ball color
27.         int ballIndex = Random.Range(0, ballPrefabs.Length);
28.         spawnInterval = Random.Range(3, 5);
29.  
30.         // Generate random ball index and random spawn position
31.         Vector3 spawnPos = new Vector3(Random.Range(spawnLimitXLeft, spawnLimitXRight), spawnPosY, 0);
32.  
33.         // instantiate ball at random spawn location
34.         Instantiate(ballPrefabs[ballIndex], spawnPos, ballPrefabs[ballIndex].transform.rotation);
35.     }
36. }

 

Ask yourself following questions:
1. When do I want a new random number? --> when the SpawnRandomBall function is called.
2. When do I want to execute the SpawnRandomBall again? --> When I have a new random number generated.
3. Does my Start function get updated? --> No, it only triggers the start of the game and calls the functions I type in there.

I fixed it like this:
Get rid of the repeat invoke in the start function and make it just an invoke to trigger the function to spawn a ball.
Invoke("SpawnRandomBall", startDelay).

Then in the SpawnRandomBall you want to set a random number between 3 and 5 every time this function is called.
spawnInterval = Random.Range(fastSpawn, lateSpawn);
Once you know the next interval you just call the same function again, but with the random interval number.
Invoke("SpawnRandomBall", spawnInterval);

Every time the SpawnRandomBall is called it will generate a new number and call the function again after that many seconds. Not sure if this is THE solution, but it works very neat.

 

Great, thank you!

 

ENGLISH (still learning it):
SpiderFlash95 is right, "InvokeRepeating()" method set the interval as "hardcode" (so you can't change it even if you're using "Random()" method/func). As he/she said, you can use "Invoke()" in the "Start()" method and then use "Invoke()" again in "SpawnRandomBall()" method.

ESPAÑOL:
SpiderFlash95 tiene razón, el método "InvokeRepeating()" establece el intervalo como "código duro" (así que no lo puede cambiar incluso si utilizas el método/función "Random()"). Como él/ella dijo, puedes usar "Invoke()" en el método "Start()" y luego usarlo de nuevo en el método "SpawnRandomBall()".

Example/Ejemplo:

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class SpawnManagerX : MonoBehaviour
6. {
7.     public GameObject[] ballPrefabs;
8.  
9.     private float spawnLimitXLeft = -22;
10.     private float spawnLimitXRight = 7;
11.     private float spawnPosY = 30;
12.  
13.     private float startDelay = 1.0f;
14.     private float spawnInterval;
15.  
16.     // Start is called before the first frame update
17.     void Start()
18.     {
19.         //InvokeRepeating("SpawnRandomBall", startDelay, spawnInterval);
20.         Invoke("SpawnRandomBall", startDelay);
21.     }
22.  
23.     // Spawn random ball at random x position at top of play area
24.     void SpawnRandomBall ()
25.     {
26.         // Random spawnInterval
27.         spawnInterval = Random.Range(3.0f, 5.0f);
28.         Invoke("SpawnRandomBall", spawnInterval);
29.         Debug.Log("Intevarlo: " + spawnInterval);
30.  
31.         // Generate random ball index and random spawn position
32.         Vector3 spawnPos = new Vector3(Random.Range(spawnLimitXLeft, spawnLimitXRight), spawnPosY, 0);
33.  
34.         // instantiate ball at random spawn location
35.         int ballIndex = Random.Range(0, ballPrefabs.Length);
36.         Instantiate(ballPrefabs[ballIndex], spawnPos, ballPrefabs[ballIndex].transform.rotation);
37.  
38.     }
39. }
40.