Insantiate once only

Questions & Answers
1

Simply, how do you insantiate an object once when using a function OnCollisionEnter? So in this script, how would you only make it instantiate one firework? (By the way, the rest of the script works - I'm not missing the function or the variables, this is just the relevent part).

if (hit.gameObject.name == "Bottom")    {

         var instance : GameObject = Instantiate(fireworks, Vector3(2159.701, -178, 3312) , transform.rotation);
         yield WaitForSeconds (5);
    }
}

Thanks!.

3

It would help to see the rest of your script, but, if you only want it to work ONCE and never again, you could do this:

var activated : boolean = false;

        if (hit.gameObject.name == "Bottom" && activated == false) {
             var instance : GameObject = Instantiate(fireworks, Vector3(2159.701, -178, 3312) , transform.rotation);
                 activated = true;
             }
         }

If you want it to work every few seconds, you could do this:

var activated : boolean = false;
var timer : float = 3.0;

        if (hit.gameObject.name == "Bottom" && activated == false) {
             var instance : GameObject = Instantiate(fireworks, Vector3(2159.701, -178, 3312) , transform.rotation);
                 activated = true;

                 //As Long As This Is Not Update

                 yield.WaitForSeconds(timer);
                 activated = false;
             }
         }

If it is update, use this:

var activated : boolean = false;
var timer : float = 3.0;

        if (hit.gameObject.name == "Bottom" && activated == false) {
             var instance : GameObject = Instantiate(fireworks, Vector3(2159.701, -178, 3312) , transform.rotation);
                 activated = true;

                 //If its not Update

                 TimerRun();
             }
         }

function TimerRun () {
    yield.WaitForSeconds(timer);
    activated = false;
}

Just so you know, I haven't tried any of these codes... If you get any errors, let me know!

-- - Hope I Helped!

2 
function OnCollisionEnter(col : Collision) {
    if (col.collider.CompareTag("Bottom")) {
        var instance = Instantiate(fireworks, Vector3(2159.701, -178, 3312) , transform.rotation);
    }
}

Please note that the above code is untested and may contain errors.