How to change onValueChanged target GameObject in a Slider during runtime?

Question

I have two canvases, one is used for my Main Menu Scene and one is used to display scores in each level. When I return to the main menu to adjust the volume, my sliders in my MainMenu/Options no longer access the Music GameObject even though the Music gameObject is set to 'DoNotDestroy' and works fine during the transition to the first level. alt text I am therefore trying to repopulate the gameObject accessed by the slider (script below).

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;

 public class MusicRePop : MonoBehaviour
 {
   Slider slider;
   OptionsSwitch musicObj;

   void Start()
   {
     slider = GetComponent<Slider>();
     musicObj = FindObjectOfType<OptionsSwitch>();
   }

   void Update()
   {
     // Debug.Log(slider.onValueChanged.GetPersistentTarget(0));
     if(slider.onValueChanged.GetPersistentTarget(0) == null){
       slider.onValueChanged.GetPersistentTarget(0) = musicObj;
     } else {
       Debug.Log(slider.onValueChanged.GetPersistentTarget(0));
     }
   }
 }

I have searched google and unity documentation (https://docs.unity3d.com/ScriptReference/UI.Slider.SliderEvent.html) and looked at the only reference to the subject that I could find ( https://answers.unity.com/questions/1453558/how-to-change-object-reference-in-slider-under-onv.html ) but this question does not provide a clear answer. Where:-

Brogan69 states this - "You don't need to do that in code."

When I run the above code I get the following error... Assets\Scripts\MusicRePop.cs(21,7): error CS0131: The left-hand side of an assignment must be a variable, property or indexer

Can any body point me in the right direction? Thanks.

Answer 1

Best Answer

Answer by Hellium · Jun 07, 2019 at 07:23 AM

Remove the object in the onValueChanged event in the inspector and add the listener by code

  using System.Collections;
  using System.Collections.Generic;
  using UnityEngine;
  using UnityEngine.UI;
  public class MusicRePop : MonoBehaviour
  {
    Slider slider;
    OptionsSwitch musicObj;
    void Start()
    {
      slider = GetComponent<Slider>();
      musicObj = FindObjectOfType<OptionsSwitch>();
      if( slider != null && musicObj != null )
          slider.onValueChanged.AddListener( value => musicObj.FunctionToCall( arguments ) ) ;
      else
          Debug.LogError("Either the slider is not attached to the GO or no OptionsSwitch in the scene" ) ;
    }
  }

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ToroidGames · Jun 07, 2019 at 01:02 PM 0

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Brilliant! Thanks so much that solved the issue. Here's the script (for anyone who needs it) -

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;

 public class $$anonymous$$usicRePop : $$anonymous$$onoBehaviour
 {
   Slider slider;
   OptionsSwitch musicObj;
   
   void Start()
   {
       slider = GetComponent<Slider>();
       musicObj = FindObjectOfType<OptionsSwitch>();
       if( slider != null && musicObj != null ){
         slider.onValueChanged.AddListener(value => musicObj.AdjustVol(slider.value)) ;
       } else {
         Debug.LogError("Either the slider is not attached to the GO or no OptionsSwitch in the scene" ) ;
       }
     }
 }

and I added this to OptionsSwitch -

   AudioSource aS;

   void Awake(){
     aS = GetComponent<AudioSource>();
   }

   public void AdjustVol(float vol){
     aS.volume = vol;
   }

Thanks again @Hellium

How to change onValueChanged target GameObject in a Slider during runtime?

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