How to spawn objects at random times? - random

Question

I am trying to create a script that will spawn objects at random times, and unfortunately mine isn't working very well. Can you please help me in randomizing the time between the spawns of the Game Objects? Thanks!
#pragma strict
var SpawnObject : GameObject;
var SpawnPoint : GameObject;
var SpawnCounter : int = 0;
var SpawnCounterMinMax : int =0;
var SpawnCounterMaxMax : int =0;
function Update ()
{
var float_min_bother_I_hate_you_js : float = this.SpawnCounterMinMax;
var float_max_bother_I_hate_you_js : float = this.SpawnCounterMaxMax;
var SpawnCounterMax = Random.Range(float_min_bother_I_hate_you_js, float_max_bother_I_hate_you_js);
this.SpawnCounter++;
if (this.SpawnCounter >= SpawnCounterMax )
{
Instantiate(this.SpawnObject, this.SpawnPoint.transform.position, this.SpawnPoint.transform.rotation );
this.SpawnCounter = 0;
SpawnCounterMax = Random.Range(float_min_bother_I_hate_you_js, float_max_bother_I_hate_you_js);
}
}

Answer 1

If you want to be able to specify a min/max random timeframe something like this should work:
#pragma strict
var SpawnObject : GameObject;
var SpawnPoint : GameObject;
var NextSpawnTime : float = 0;
var MinSpawnTime : float =0;
var MaxSpawnTime : float =0;
function SetTimer()
{
this.NextSpawnTime = Random.Range(this.MinSpawnTime, this.MaxSpawnTime);
}
function Start ()
{
//initialise the spawn counter at startup
this.SetTimer();
}
function Update ()
{
this.NextSpawnTime -= Time.deltaTime;
if(this.NextSpawnTime <= 0)
{
Instantiate(this.SpawnObject, this.SpawnPoint.transform.position, this.SpawnPoint.transform.rotation );
this.SetTimer();
}
}
Using Time.deltaTime to decrement a timer that stores some value in seconds ensures that your spawns happen in the given range regardless of framerate.
To further clarify why you might be seeing unwanted behaviour in your code. You are re-randomising the max value for SpawnCounter each update, rather than setting it once each time an object is spawned.

Answer 2

You could use a coroutine to achieve this, something like this would do.
int numberOfObjectsToCreate = 5; // number of objects you want to spawn.
float minTimeDiff = 1.0f; // minimum time difference between 2 objects spawned.
float maxTimeDiff = 5.0f; // Maximam time difference between 2 spawns.
public GameObject ObjectToSpawn; // object that is to be spawned;
void Start() {
StartCoroutine(CreateObjectsAtRandom());
}
IEnumerator CreateObjectsAtRandom() {
for(int i = 0; i < numberOfObjectsToCreate; i++) {
GameObject obj = Instantiate(ObjectToSpawn, Vector3.zero, Quarternion.identity) as GameObject;
yield return new WaitForSeconds(Random.Range(minTimeDiff, maxTimeDiff)); // wait for a random time before spawning the next object.
}
}