How does FindGameObjectsWithTag work?

Question

I was just curious if anyone knew specifically how GameObject.FindGameObjectsWithTag worked.

Is there some sort of dictionary that these tags and gameobjects and whatnot are a part of?

or is it the equivalent to

 foreach(GameObject go in FindObjectsOfType(typeof(GameObject)))
 {
     if(go.tag == "butts")
     {
         return go;
     }
 }

I was just curious about how efficient it is to use if you are trying to grab a group of objects with the same tag

Answer 1

Best Answer

Answer by aldonaletto · Oct 03, 2013 at 04:12 AM

Apparently, the tag is internally stored in the GameObject as an integer, probably the index of the actual tag name in the tag table - that's why you must register a tag before using it. Since GameObject.tag is a property, its getter function returns the corresponding string stored in the tag table. I don't know if there exists some additional mapping to speed up tag search, but comparing integers is way faster than comparing strings, what makes FindWithTag faster than Find("tagName").

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Answer 2

Answer by TrickyHandz · Oct 03, 2013 at 03:20 AM

All of the Find functions for GameObjects [Find(), FindGameObjectsWithTag(), FindWithTag()] are notoriously inefficient. At one of the Unite 13 talks one of the programmers at Unity stated that you shouldn't use these unless absolutely necessary. The recommendation I have heard most often is to register gameobjects to into a custom data structure that is easily and efficiently traversable.

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Answer 3

Answer by r-dotfunky · Oct 03, 2013 at 03:49 AM

To answer your question though, when you select an item in your scene heirarchy, on the right side (assuming std Unity setup), you'll see at the top a "Tag" menu. You can add custom tags to that, then assign your objects to the tag.

The FindGameObjectsWithTag function should return an array of GameObjects.

http://docs.unity3d.com/Documentation/ScriptReference/GameObject.FindGameObjectsWithTag.html

[code] GameObject[] gos; gos = GameObject.FindGameObjectsWithTag("Enemy"); [/code]

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Ziplock9000 · Jul 16, 2019 at 06:50 PM 0

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That wasn't the question.

How does FindGameObjectsWithTag work?

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