Create only one Instantiated Object

Questions & Answers
1

Okay guys - I can’t figure this one out. I have a day night cycle going by the rotation of the directional light, and at night I need a fire particle system prefab I have to start up, and during the day I need it to go away. How I have it set up right now, it creates to many instances and possibly would kill the game object rather than the instance? I need this Day- No fire/ Night - Fire cycle to continue for an infinite amount of time. Here is the scripts I have

This one is for the rotation of the light and to tell something that the rotation is correct for Day time or Night time

#pragma strict

public static var TimeOfDay : float = 0.0; 
public static var LightRotation : float = 0.0;

function Update()
	{
    transform.Rotate(Vector3.right / 3.0);
    LightRotation = transform.eulerAngles.x; 

    if (LightRotation <= 150) {
        TimeOfDay = 0.0;
        BroadcastMessage("KillFire");
        Debug.Log(TimeOfDay);
    }
    else if (LightRotation >= 150) {
        TimeOfDay = 1.0;
        BroadcastMessage("StartFire");
        Debug.Log(TimeOfDay);
    }
}

This is what I have on the empty object to create the fire instance

#pragma strict

public var prefab : GameObject;;

function KillFire(){
    Destroy(prefab);
}

function StartFire(){
    Instantiate(prefab,transform.position, Quaternion.identity);
}

Any and all help would be greatly appreciated. Thank you!

2

First, you’re destroying the prefab, not the instance, that KillFire won’t work as expected. You have to keep a referente to the instance of the fire and destroy that reference.

That also works for your actual question. You’re calling StartFire every frame if LightRotation is greater than 150, so you’re creating an instance every frame. Keeping a reference to the instance you can check if it’s null before doing the Instantiate code.

Anyway, a cleaner approach would be to only broadcast the messages if LightRotation passed 150 in that same frame. SendMessage and BroadcastMessage are expensive and shouldn’t be called if will be ignored by the receiver.