[Solved] Why not use ("Breakable").Lenght

During the pause session in this lesson I came up with the solution (that seem to work)
First declare it as in example but without a value;

public static int breakableCount;

Then in the start I searched for gameobjects with the tag breakable and set that to the int.

void Start () {
breakableCount = GameObject.FindGameObjectsWithTag(“Breakable”).Length;

In the HandleHits() //My code is a bit differently named

if (currentSprite > arrayLength){
deleting = true;
if(breakableCount <= 0){

I’m just curious really to find out if there are any performance issues doing it this way instead?

I’m curious about this as well. During the pause I did that as well, up to calling the LevelManager LoadNextLevel() function when it reaches 0 and it loads the next level just fine when all bricks are destroyed. Performance wise it makes sense to me since just at the start you get a count of them, and every time a brick is actually destroyed it decrements that static value and only calls LoadNextLevel() when it hits 0 bricks left.

Actually now that I think about it… is the performance issue where we are using the breakableCount = GameObject.FindGameObjectsWithTag(“Breakable”).Length; ?

I figure every time a brick is created and it has that script it calls that find function. It must be more performance heavy than just calling a breakableCount++ everytime a brick is created. Can anyone confirm :slight_smile: ?

All Find() methods are going to be an overhead, as such, you want to minimise them where-ever you can.

If @Assistenten’s example is in the Start() method on the Brick object, then it is setting that static variable every single time a Brick is instantiated. So, a level with 200 bricks will call the FindGameObjectsWithTag() method 200 times and 199 of them will not be required as you have already set the variable to equal 200.

Arguably, you could put a check around it to see if it has already been set. You might initially set breakableCount to -1 instead of 0 (zero), and then within the Start() method only perform the find if it no longer equals -1. You would, of course, need to reset this to equal -1 before loading the new levels instead of 0. We would use -1 insetad of 0 (zero) as you require 0 (zero) for checking that all of the bricks have been destroyed if they are breakable.

public static int breakableCount = -1;

void Start () 
    if(breakableCount = -1)
        breakableCount = GameObject.FindGameObjectsWithTag("Breakable").Length;

When I consider all of the things we are now having to do to facilitate the ease of using the .Length property of the collection returned by the FindGmeObjectsWithTag() method, it’s not feeling as straight forward as just checking the tag for the brick that was instantiated and using breakableCount++;.

isBreakable = (this.tag == "Breakable");

// keep track of breakable bricks
if (isBreakable)

…the above seems straightforward, sufficient and doesn’t require additional validation to prevent the performance issues.

I hope this is helpful. :slight_smile:

Updated Sat Jun 24 2017 19:08

You may also get an error if you were to create a scene with no breakable bricks - I know you wouldn’t typically have this because it wouldn’t be a playable/winable level - but according to the Unity documentation null will be returned if nothing is found with corresponding tags, as such you would be trying to then access the .Length property of a null object, which should cause an error immediately.

Potentially therefore, you should protect against that with some more code too!

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Thanks! Great answer, I did not realiase that the Start() would be called on every brick, after your explaination it all makes more sense to do it that way. Thanks a bunch!

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You’re more than welcome. :slight_smile:

There’s a really useful diagram on the page linked below, any behaviour (any class implementing MonoBehaviour) will follow the shown order of execution.

Thus each Brick has a Brick class attached, which implements MonoBehaviour, and will have an Awake(), Start() and Update() methods called etc. Hence, number of Bricks * Find() method. :slight_smile:

See also;

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