CODEWITHSUNDEEP
c#unity-game-enginescene
Peter Smith
Peter Smith

Reputation: 21

Check the previous loaded scene

I'm making a game in Unity3D with C# for mobile devices and can't figure out how to check which scene was loaded before the current scene. I need to check this to change the spawn point from the player gameobject. First I added a simple script to my buttons (loadnextscene and loadprevscene)

public class SwitchScene : MonoBehaviour {
    public int sceneNumber;

    public void LoadScene(int sceneNumber) {
        Application.LoadLevel(sceneNumber);
    }
}

A second scripts handles the touch input from the user and changes the movement of the player object.

So, for example: If the player clicks on the "load previous scene" button in the second Level to switch to the first level again, I want to set the spawn point of the player object on the right half on the screen and not on the left side like when the game was started the first time.

I tried it with Singleton and PlayerPrefs, but it did not work out.

Upvotes: 2

Views: 9792

Answers (3)

James Vanderhyde
James Vanderhyde

Reputation: 374

You can solve this problem with a single static member variable in the SwitchScene class. No need for the singleton pattern or DontDestroyOnLoad.

public class SwitchScene : MonoBehaviour
{
    public int sceneNumber;
    private static int previousScene;
    private int oldPreviousScene;

    void Start()
    {
        oldPreviousScene = previousScene;
        previousScene = sceneNumber;
    }

    public void HandleLoadPrevButtonClick()
    {
        SceneManager.LoadScene(oldPreviousScene);
    }
}

Upvotes: 1

nir
nir

Reputation: 11

Why did the PlayerPrefs approach did not work? I think its the easiest way to solve your problem.

public class FirstLevel : MonoBehaviour {
    public void Start() {
        PlayerPrefs.SetString("SceneNumber", SceneManager.GetActiveScene().name);
    }
}

And then in the second scene simply read the saved PlayerPrefs

public class SecondLevel : MonoBehaviour {
    string PrevScene;
    public void Start() {
        PrevScene = PlayerPrefs.GetString("SceneNumber");
        // if there will be a third scene, etc.
        PlayerPrefs.SetString("SceneNumber", SceneManager.GetActiveScene().name);
    }
    public void GoToPrevScene() {
        SceneManager.LoadScene(PrevScene);
    }
}

Upvotes: 1

Yuri Nudelman
Yuri Nudelman

Reputation: 2943

You need to save the scene number to some variable before LoadScene, then check it after the scene loaded. The only problem is that this variable will be destroyed after the new scene is loaded. So, to prevent it, you can use DontDestroyOnLoad. Here is what you do:

First, create a new empty game object, and attach the following script to it:

using UnityEngine;
using System.Collections;

public class Indestructable : MonoBehaviour {

    public static Indestructable instance = null;

    // For sake of example, assume -1 indicates first scene
    public int prevScene = -1;

    void Awake() {
        // If we don't have an instance set - set it now
        if(!instance )
            instance = this;
        // Otherwise, its a double, we dont need it - destroy
        else {
            Destroy(this.gameObject) ;
            return;
        }

        DontDestroyOnLoad(this.gameObject) ;
    }
}

And now, before you load, save the scene number in the Indestructable object:

public class SwitchScene : MonoBehaviour {
    public int sceneNumber;
    public void LoadScene(int sceneNumber) {
        Indestructable.instance.prevScene = Application.loadedLevel;

        Application.LoadLevel(sceneNumber);
    }
}

And last, in your scene Start() check Indestructable.instance.prevScene and do your magic accordingly.

More info here: http://docs.unity3d.com/ScriptReference/Object.DontDestroyOnLoad.html

*I did not compile the code, so there may be some errors, but this is the general idea.

Upvotes: 3

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