How do I call a function in another gameObject's script?

I have a gameObject A with script A, how do I then call a function in gameobject b's script b?

5 Answers

5

Like this:

using UnityEngine;
public class ScriptA : MonoBehaviour
{
  public ScriptB other;

  void Update()
  {
    other.DoSomething();
  }
}

and in a seperate script:

using UnityEngine;
public class ScriptB : MonoBehaviour
{
  public void DoSomething()
  {
     Debug.Log("Hi there");
  }
}

Notice how ScriptA has a public field, with a type of ScriptB. This is a nice trick, where you can now drag a gameobject that has a ScriptB attached onto this "other" field in the editor. Unity automatically realizes that you didn't ask for a gameobject, but you asked for a ScriptB, so it will fill that field with the ScriptB instance, instead of with the gameObject.

Alternatively, if you don't like the "direct reference" made in the Editor by dragging the gameobject with scriptb onto the "other" variable, you can get a reference trough GameObject.Find("somename") instead:

GameObject go = GameObject.Find("somegameobjectname");
ScriptB other = (ScriptB) go.GetComponent(typeof(ScriptB));
other.DoSomething();

GameObject.Find() is a pretty slow operation though, so whenever you can do the direct reference, that's recommended.

For more detailed information see this section of the help: http://unity3d.com/support/documentation/ScriptReference/index.Accessing_Other_Game_Objects.html

Ah, hehe, you submited too while I was preparing the answer... :-)

added your gameobject.find alternative to my answer to make it more complete

As I realized I'm not the only one who got confused by the "using UnityEngine;" and "public class"-declaration ... I'd like to point out that Lucas' answer is C#, while Martin's (and the Script-reference-link) are JS.

Great thread. But how do you call functions between GO's when one of them is instantiated and one is not. For example, between the player (who is not instantiated) and an enemy who is. You cannot direct reference in this case and Find() is too slow.

Actually, the problem with "Find" is only a real problem when you do it frequently. What you'd usually do in that case (an object being instantiated at a later point in time): Do Find() once (e.g. only if you don't have the reference, yet) and then store it in a member variable (as in the above example).

This can either be done by a static reference (if you know the other object already upfront) or a dynamic lookup (finding a gameObject at runtime).

With a static reference, you create a link from ScriptA to gameObject b's ScriptB and call then any function in ScriptB. Example:

ScriptA attached to gameObject a:

var linkToScriptB : ScriptB;

function Update()  {
   ...
}

Now in the inspector, drag gameObject b with ScriptB attached to it to the free linkToScriptB slot in the gameObject A's script. Et voila, you can call now inside ScriptA a function like "Test()" in ScriptB like this:

linkToScriptB.Test();

The dynamic lookup is used when you don't know gameObject b upfront, but sometime later in your game. Then, instead of linking it in the inspector, you call at the appropriate place in your script something like this (in ScriptA):

linkToScriptB = GameObject.Find("gameObjectA").GetComponent(ScriptB);
linkToScriptB.Test();

The function "GameObject.Find(..)" will locate the other gameObject by its name. The return value would be a gameObject. Now that we want the ScriptB from that gameObject, we retrieve a reference to the ScriptB by calling the GetComponent function.

Martin Schultz wrote, "var linkToScriptB : ScriptB;" Don't you mean: "var linkToScriptB : MonoScript;" ? Otherwise, Unity returns an error.

Very helpful tip, though. Thanks.

OK, I see. Thanks.

Also note there is a section called Accessing Other Game Objects in the Unity Script reference documentation that expands upon this in detail.

@Keli_Hlodversson The link is correct BUT the that section of the docs is down error "PageNotFound"

[Updated link to - Accessing Other Game Objects][1] [1]: http://docs.unity3d.com/412/Documentation/ScriptReference/index.Accessing_Other_Game_Objects.html

I click the link and it say: Page not found. Please update the link.

Current link: https://docs.unity3d.com/410/Documentation/ScriptReference/index.Accessing_Other_Game_Objects.html

Link (2019.2) — https://docs.unity3d.com/Manual/ControllingGameObjectsComponents.html

public class ScriptA : MonoBehaviour
{
public GameObject other;

   void Update()
   {
     other.GetComponent<ScriptB>().DoSomething();
   }
 }

Hi! I also had this problem and I got answers from this link.

Here