2

I just started using Unity and I want to build the following function: Currently I press a button which spawns an asteroid outside of the screen, then the asteroid moves through the screen from right to left and finally I destroy the asteroid out of screen. All this is working already. But now I want to change the button function so that it spawns more asteroids delayed by a few seconds. And I don't know how to do that. My Code looks like this at the moment:

public class ButtonSkript : MonoBehaviour
{       
    private Vector3 spawnPosition = new Vector3(15, 0, 0);
    public GameObject planet_001Prefab;
    public GameObject planet_011Prefab; // not in use
    public GameObject planet_017Prefab; // not in use
    public GameObject planet_079Prefab; // not in use
    

    public void ShowJourney()
    {
        int[] asteroids_array = {27, 569, 1293, 37};
        int[] material_type_array = {0, 2, 1, 3}; // not in use
        
        for (int i  = 0; i < asteroids_array.Length; i++) {
            GameObject a = Instantiate(planet_001Prefab);
            a.transform.position = spawnPosition;
        
            Destroy(a, 3);

            // wait for 3 seconds
        }
    }
}


public class Translate : MonoBehaviour
{
    public float speed = 10.0f;


    // Update is called once per frame
    void Update()
    {
        moveAsteroid(new Vector2(-1, 0));
    }
    
    void moveAsteroid(Vector2 direction)
    {
        transform.Translate(direction * speed * Time.deltaTime);
    }
}

I already tried System.Threading.Thread.Sleep(3000); and I also tryed to build a timer with IEnumarate and yield return new waitForSeconds(3.0f); but both things are not working or I didn't implement it correctly.

It is probably an easy question, but I can't figure it out on my own.

Thanks for the help :)

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3
  • can you show the complete method? Commented Dec 29, 2022 at 15:30
  • i updated the post and it now includes the full method Commented Dec 29, 2022 at 15:46
  • A coroutine is your friend. Commented Dec 30, 2022 at 1:29

3 Answers 3

Reset to default
2

The StartCoroutine method is a little like a fire-and-forget method. It’ll start a new coroutine, without actually waiting to see what the coroutine is doing. So, your initial attempt at looping through and starting ‘n’ coroutines is doing exactly that - starting 4 new coroutines all at the same time.

A potential fix in this situation might be:

int[] asteroids_array = {27, 569, 1293, 37};
int[] material_type_array = {0, 2, 1, 3}; // not in use

public void ShowJourney()
{
    StartCoroutine(Spawn());
}

IEnumerator Spawn()
{
    for (int i  = 0; i < asteroids_array.Length; i++)
    {
        var a = Instantiate(planet_001Prefab);
        a.transform.position = spawnPosition;
        Destroy(a, 3); // could be here, or after the WaitForSeconds.
        yield return new WaitForSeconds(3);
    }
}

Note that there’s no check to see if the coroutine is running, so if you have a button attached to ShowJourney you might still end up with lots of coroutines running.

If each asteroid followed your logic, you could also just reposition the asteroid instead of creating a new one. For example:

IEnumerator Spawn()
{
    var a = Instantiate(planet_001Prefab);
    a.transform.position = spawnPosition;
    for (int i  = 0; i < asteroids_array.Length; i++)
    {
        yield return new WaitForSeconds(3);
        a.transform.position = spawnPosition;
    }
    Destroy(a);
}

But this just illustrates that there’s often many ways to accomplish the outcome you’re looking for.

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1 Comment

Thank you so much :) I tryed your code and it is working really well!
1

Trigger a Coroutine that yields for 3 seconds and then spawns the assets.

This will allow for execution to continue to compute the current frame while your coroutine runs in parallel.

Reference: https://docs.unity3d.com/Manual/Coroutines.html

key command: yield return new WaitForSeconds(3.0f);

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4 Comments

I tryed your idea like this, but it is not working. it spawns all the asteroids on top of each other because the programm is not waiting. What did i do wrong? I added this method: ' IEnumerator Wait() { yield return new WaitForSeconds(3.0f); } ' and in the method in my question i added 'StartCoroutine(Wait());'
You need to put the code for spawning in the coroutine after your yield return... statement.
I tryed it like this: In the for-loop i only said for (int i = 0; i < asteroids_array.Length; i++) { StartCoroutine(Test()); } and then i call IEnumerator Test() { GameObject a = Instantiate(planet_001Prefab); a.transform.position = spawnPosition; Destroy(a, 3); yield return new WaitForSeconds(3.0f); } but the same problem as before. I spawn all 4 asteroids for all 4 elements in my array at the same time.
@SeanMiller - Please show the OP the correct code in your answer.
0

You can create an async method and wait 3 seconds for each iteration.

Your method will look like this`

public async  Task ShowJourney()
{
    int[] asteroids_array = {27, 569, 1293, 37};
    int[] material_type_array = {0, 2, 1, 3}; // not in use
    
    for (int i  = 0; i < asteroids_array.Length; i++) {
        GameObject a = Instantiate(planet_001Prefab);
        a.transform.position = spawnPosition;
    
        Destroy(a, 3);

        await Task.Delay(3);
    }
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1 Comment

I think this is a good idea, but it stills spawns 4 asteroids at the same time and is not waiting. And to run it, I needed to change the head of the method to public async void ShowJourney() instead of public async Task ShowJourney().

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