How to instantiate a prefab after a certain action happened?

Questions & Answers
1

So I’m making this horror game and I am trying to make it so that when a certain door opens, something spawns for a very brief moment at the door.

So for the door i am going to use a boolean variable that keeps track of whether or not the door is open, using if statements.

But for the object that spawns i am not really sure what to do. I am thinking about an if statement like this:

if (GetComponent(“DoorScript”).isDoorOpen = true)
{
instantiate the prefab
}

What should be where “instantiate the prefab” is now?

Thanks in advance and i hope i explained it in enough detail.

3

Ok, I am going to give you this one, as it can be confusing how to only make something happen once in a game lifetime, and you have shown effort in thinking about the problem.

You have the right idea with a boolean, so lets start there :

var hasShownDoorPopup : boolean = false;

now GetComponent is quite heavy on the processor, so let’s first check if the door popup has been done :

// note the ! this is the same as saying if ( hasShownDoorPopup == false )
if ( !hasShownDoorPopup ) 
{
    //
}

so now the DoorScript can be checked. Remember to use == in a conditional (you only have one equals in your example if statement). Also try not to use strings when using GetComponent, just typecast to the name of your script :

if ( GetComponent( DoorScript ).isDoorOpen == true ) { // .... }

After that, instantiate your prefab , and then set hasShownDoorPopup to true. Now this part of the code will not be executed again in the current game lifetime.

Here is a full example :

var hasShownDoorPopup : boolean = false;

// in your function
if ( !hasShownDoorPopup )
{
    if ( GetComponent( DoorScript ).isDoorOpen == true ) 
    {
        // instantiate prefab
        
        // set boolean to true so this doesn't happen again
        hasShownDoorPopup = true;
    }
}
2

You almost answered yourself : Use the Instantiate function
Something like:

Instantiate(YourPrefab, new Vector3(X, Y, Z), [Quaternion.identity][1])

A little advice. If you’re using this line “if (GetComponent(“DoorScript”).isDoorOpen = true)” in an Update() function, you should consider storing it before (may be in the Start() function, because GetComponent is slow.