Handling Scene Management, function not visible

Unity Engine
1

Hi, I’ve followed this video

to create a Scene Manager.
I created a Canvas prefab which makes the transitions between scenes and I added it in my main menu scene (which has another canvas that handles the menu) and I’ve attached to it the next script:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;

public class SceneController : MonoBehaviour {

    public static SceneController MyInstance;
    //It's a static instance thnt won't be destroyed over scenes

    public float TransitionTimeDelay=0.1f;
    public string TargetScene;
    CanvasGroup MyCanvasGroup;

    bool IsAddictive;

    // Use this for initialization
    void Awake () {

        //Check if we have duplicated instances of the same class and in case we do, delete one
        if (MyInstance == null) {
            MyInstance = this;
            DontDestroyOnLoad (gameObject);                            //The gameObject is the Canvas
            MyCanvasGroup=GetComponent<CanvasGroup>();
        } else
            Destroy (gameObject);


    }
   
    // Update is called once per frame
    void Update () {
        //That's only for test
        if (Input.GetKey (KeyCode.Q))
            SetTargetScene ("Scena", false);
    }



    public void SetTargetScene(string SceneToLoad, bool Addictive)
    {
        //If we're pointing to the same scene, quit the function
        if (SceneManager.GetActiveScene ().name == SceneToLoad)
            return;
        TargetScene = SceneToLoad;
        IsAddictive = Addictive;

        StopCoroutine ("TransitionWithFade");
        StartCoroutine ("TransitionWithFade", 1);

        //Set the target alpha to 1, so to be completely opaque
    }

    //Coroutine that operates while loading the next scene
    IEnumerator TransitionWithFade(float targetAlpha)
    {
        float AlphaDifference = Mathf.Abs (MyCanvasGroup.alpha - targetAlpha);
        float TransitionRate = 0;

        while (AlphaDifference > 0.045f) {
            //Smoothen the transition between the two scenes.
            //Syntaxis: current alpha ! target alpha | current velocity | transition time
            MyCanvasGroup.alpha = Mathf.SmoothDamp (MyCanvasGroup.alpha, targetAlpha, ref TransitionRate, TransitionRate);
            AlphaDifference = MyCanvasGroup.alpha - targetAlpha;                    //Update Alpha difference between scenes/image

            yield return null;              //Interrups coroutine
        }

        MyCanvasGroup.alpha = targetAlpha;

        //When MyCanvasGroup.alpha is 1 (fully opaque), it means we have to move to the next scene, so we need to call the actual method doing that.
        if (targetAlpha == 1) {
            StartCoroutine ("LoadScene");
        }
    }

    IEnumerator LoadScene()
    {
        if(IsAddictive==false)
            SceneManager.LoadScene (TargetScene);                            //Load the correct scene
        else
            SceneManager.LoadScene (TargetScene, LoadSceneMode.Additive);
       
        string ActiveScene=SceneManager.GetActiveScene().name;            //Refresh the current scene

        //If the scene is not loaded yet, so it means our current scene is not the target scene (because of slow PC performance, troubles etc...)
        //Continue with the coroutine until the desired scene is completely loaded
        while (ActiveScene != TargetScene) {
            ActiveScene = SceneManager.GetActiveScene ().name;
            yield return null;
        }

        StartCoroutine ("TransitionWithFade", 0);            //When the scene is loaded, turn the canvas group alpha to be 0

    }
}

I have some scenes in my assets and I will create new ones.
Unfortunately in the main scene where I have a “Play” button, if I add an OnClick event, I drag the canvas element that handles the scene management, I cannot see my “SetTargetScene method” even if it is public.

So I cannot set what scene to upload when pressing the button.
What can I do?

Thank you for any help

2

I could be wrong, but I think those events only accept 0 or 1 arguments by default.
So, you could setup intermediate methods to handle that (like 2 make ).
Or you could shorten the method parameter list , if you don’t need the second argument.
or something else along those lines…

3

I created another Canvas and edited the code as it follows:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;

public class SceneController : MonoBehaviour {

    public static SceneController MyInstance;
    //It's a static instance thnt won't be destroyed over scenes

    public float TransitionTimeDelay=0.1f;
    public string TargetScene;
    CanvasGroup MyCanvasGroup;

    int IsAddictive=0;

    // Use this for initialization
    void Awake () {

        //Check if we have duplicated instances of the same class and in case we do, delete one
        if (MyInstance == null) {
            MyInstance = this;
            DontDestroyOnLoad (gameObject);                            //The gameObject is the Canvas
            MyCanvasGroup=GetComponent<CanvasGroup>();
        } else
            Destroy (gameObject);


    }
   
    // Update is called once per frame
    void Update () {
        //That's only for test
        if (Input.GetKey (KeyCode.Q))
            SetTargetScene ("Scena", 0);
    }



    public void SetTargetScene(string SceneToLoad, int Addictive)
    {
        //If we're pointing to the same scene, quit the function
        if (SceneManager.GetActiveScene ().name == SceneToLoad)
            return;
        TargetScene = SceneToLoad;
        IsAddictive = Addictive;

        StopCoroutine ("TransitionWithFade");
        StartCoroutine ("TransitionWithFade", 1);

        //Set the target alpha to 1, so to be completely opaque
    }

    //Coroutine that operates while loading the next scene
    IEnumerator TransitionWithFade(float targetAlpha)
    {
        float AlphaDifference = Mathf.Abs (MyCanvasGroup.alpha - targetAlpha);
        float TransitionRate = 0;

        while (AlphaDifference > 0.045f) {
            //Smoothen the transition between the two scenes.
            //Syntaxis: current alpha ! target alpha | current velocity | transition time
            MyCanvasGroup.alpha = Mathf.SmoothDamp (MyCanvasGroup.alpha, targetAlpha, ref TransitionRate, TransitionRate);
            AlphaDifference = MyCanvasGroup.alpha - targetAlpha;                    //Update Alpha difference between scenes/image

            yield return null;              //Interrups coroutine
        }

        MyCanvasGroup.alpha = targetAlpha;

        //When MyCanvasGroup.alpha is 1 (fully opaque), it means we have to move to the next scene, so we need to call the actual method doing that.
        if (targetAlpha == 1) {
            StartCoroutine ("LoadScene");
        }
    }

    IEnumerator LoadScene()
    {
        if(IsAddictive==0)
            SceneManager.LoadScene (TargetScene);                            //Load the correct scene
        else
            SceneManager.LoadScene (TargetScene, LoadSceneMode.Additive);
       
        string ActiveScene=SceneManager.GetActiveScene().name;            //Refresh the current scene

        //If the scene is not loaded yet, so it means our current scene is not the target scene (because of slow PC performance, troubles etc...)
        //Continue with the coroutine until the desired scene is completely loaded
        while (ActiveScene != TargetScene) {
            ActiveScene = SceneManager.GetActiveScene ().name;
            yield return null;
        }

        StartCoroutine ("TransitionWithFade", 0);            //When the scene is loaded, turn the canvas group alpha to be 0
    }

}

If I press the Q button the scene changes, but I cannot still see SetTargetScene in Button—>OnClick event

4

Right, well that makes sense because you didn’t make a new method. You kinda chose a slghtly different path.
What I was meaning was this:

public void SetMyScene(string SceneToLoad) {
   SetTargetScene(SceneToLoad, 0);
}

Something like that , I think then you could see the variable in the inspector

1 Like
5

Hi, I’m having another trouble with this script. I decided not to create a new thread because I think it’s not relevant.

My new SceneController.cs is as follows:

public class SceneController : MonoBehaviour {



    public float TransitionTimeDelay=0.1f;
    string TargetScene;
    CanvasGroup MyCanvasGroup;

    int IsAddictive=0;

    public string WhichButton = "";

    public GameObject Resume;


    public static SceneController MyInstance;
    //It's a static instance thnt won't be destroyed over scenes
    // Use this for initialization
    void Awake () {

        //Check if we have duplicated instances of the same class and in case we do, delete one
        if (MyInstance == null) {
            MyInstance = this;
            DontDestroyOnLoad (gameObject);                            //The gameObject is the Canvas
            MyCanvasGroup=GetComponent<CanvasGroup>();
        } else
            Destroy (gameObject);

        if (MyInstance.WhichButton.CompareTo ("Play") == 0 || MyInstance.WhichButton.CompareTo ("Resume") == 0)
            Resume.SetActive (true);
    }

    public void SetTargetScene(string SceneToLoad, int Addictive)
    {
        //If we're pointing to the same scene, quit the function
        if (SceneManager.GetActiveScene ().name == SceneToLoad)
            return;
        TargetScene = SceneToLoad;
        IsAddictive = Addictive;

        StopCoroutine ("TransitionWithFade");
        StartCoroutine ("TransitionWithFade", 1);

        //Set the target alpha to 1, so to be completely opaque
    }

    //Coroutine that operates while loading the next scene
    IEnumerator TransitionWithFade(float targetAlpha)
    {

        yield return new WaitForSeconds(2);

        float AlphaDifference = Mathf.Abs (MyCanvasGroup.alpha - targetAlpha);
        float TransitionRate = 0f;

        while (AlphaDifference > 0.025f) {
            //Smoothen the transition between the two scenes.
            //Syntaxis: current alpha ! target alpha | current velocity | transition time
            MyCanvasGroup.alpha = Mathf.SmoothDamp (MyCanvasGroup.alpha, targetAlpha, ref TransitionRate, TransitionTimeDelay);
            AlphaDifference = MyCanvasGroup.alpha - targetAlpha;                    //Update Alpha difference between scenes/image

            yield return null;              //Interrups coroutine
        }

        MyCanvasGroup.alpha = targetAlpha;

        //When MyCanvasGroup.alpha is 1 (fully opaque), it means we have to move to the next scene, so we need to call the actual method doing that.
        if (targetAlpha == 1) {
            StartCoroutine ("LoadScene");
        }
    }

    IEnumerator LoadScene()
    {
        if(IsAddictive==0)
            SceneManager.LoadScene (TargetScene);                            //Load the correct scene
        else
            SceneManager.LoadScene (TargetScene, LoadSceneMode.Additive);
       
        string ActiveScene=SceneManager.GetActiveScene().name;            //Refresh the current scene

        //If the scene is not loaded yet, so it means our current scene is not the target scene (because of slow PC performance, troubles etc...)
        //Continue with the coroutine until the desired scene is completely loaded
        while (ActiveScene != TargetScene) {
            ActiveScene = SceneManager.GetActiveScene ().name;
            yield return null;
        }

        StartCoroutine ("TransitionWithFade", 0);            //When the scene is loaded, turn the canvas group alpha to be 0
    }

    public void MyMethod()
    {
        //GameObject.Find ("Play").GetComponent<Animator> ().SetTrigger ("Pressed");
        Vector3 temp=new Vector3(0.0f,0.0f,-2f);
        this.transform.position = temp;

        SetTargetScene ("Scena", 0);
    }

    public void ChangeScenesWithButton(string whatScene)
    {       
        SetTargetScene (whatScene, 0);
    }

    public void SetButtonPressed(string PlayorResume)
    {
        //Sets a variable that stores data wether I pressed Play or Resume button.
        WhichButton=PlayorResume;
    }
}

I have added a SetButtonPressed method that sets me the name of the button pressed. It can be either “Play” or “Resume”.

I don’t know if I’d said that in the original post, but SceneManager is an empty object on which SceneController.cs is attached.
SceneManager is undestroyable and I created it in my Menu scene the first time.

My scene sequence is: Intro<Menu(where I created SceneManager)<Loading<MainGame.

In MainGame scene I have a script attached to the player that saves his last position.
That script contains:

    void Start()
    {
        if (SceneController.MyInstance.WhichButton.CompareTo("Resume")==0)        //If the game was temporary suspended, load last saved position
            RetreiveData ();
        else
            MyTransform.position = new Vector3 (34.88506f, 0.908f, 91.97422f);    //Otherwise position the player in front of the main access
    }

Another script that handles the player’s healthbar contains:

    void Start()
    {
        animator = GetComponent<Animator>(); // Determination the animator
        width = ContentLine.rect.width; // Define the object width "Content"

        if (SceneController.MyInstance.WhichButton.CompareTo("Resume")==0) {
            currentHp = PlayerPrefs.GetFloat ("Health", 100f);
        } else
            currentHp = 0f;
    }

The RecordLastPos script and the latter both give me the following NullException: “Object reference not set to an instance of an object”.

I have taken many ways attempting to solve it but with no result.
Could you have any idea of what it can be?

Thanks

6

Is the null reference on the MyInstance you mean?

7

No, in the if statements of the last two scripts