Local variable looses its values

Unity Engine
1

Hi all,

I’m having problems displaying a variable in my OnCollsionEnter() function.
I have created a datamanager class to hold all my variables so I can retrieve them from any script:

using UnityEngine;
using System.Collections;

// This script holds any data that is to be passed from script to script

public class dataManager 
{
	private Vector3 d_lightPos, d_cubePos;
	private GameObject d_Grid;
	private short d_Count;
	private int d_Lights;
	private ArrayList obsPos = new ArrayList();
	private ArrayList lgtPos = new ArrayList();
	
	public void setCubePosition(Vector3 cubePos)
	{
		d_cubePos = cubePos;
	}
	
	public Vector3 getCubePosition()
	{
		return d_cubePos;
	}
	
	public void setLightPosition(Vector3 lightPos)
	{
		d_lightPos = lightPos;
	}
	
	public Vector3 getLightPosition()
	{
		return d_lightPos;
	}
	
	public void setGridPiece(GameObject p_Grid)
	{
		if (p_Grid == null)
		{
			p_Grid = new GameObject();	
		}
		else
		{
			d_Grid = p_Grid;
		}
	}
	
	public GameObject getGridPiece()
	{
		return d_Grid;
	}
	
	public void setObstacleCount(short p_Count)
	{
		d_Count = p_Count;
	}
	
	public short getObstacleCount()
	{
		return d_Count;
	}
	
	public void setLightsOnCount(int p_Count)
	{
		d_Lights = p_Count;	
	}
	
	public int getLightsOnCount()
	{
		return d_Lights;
	}
	
	public void setObstaclePosition(Vector3 d_Pos)
	{
		if (d_Pos == Vector3.zero)
		{
			d_Pos = new Vector3(0,0,0);
			obsPos.Add(d_Pos);
		}
		else
		{
			obsPos.Add(d_Pos);
		}
	}
	
	public Vector3 getObstaclePosition(short index)
	{
		return (Vector3)obsPos[index];
	}
	
	public void setLightPositionList(Vector3 d_Pos)
	{
		if (d_Pos == Vector3.zero)
		{
			d_Pos = new Vector3(0,0,0);
			lgtPos.Add(d_Pos);
		}
		else
		{
			lgtPos.Add(d_Pos);
		}
	}
	
	public Vector3 getLightPositionList(short index)
	{
		return (Vector3)lgtPos[index];	
	}
}

And in my cubecollider class I call the functions I need:

using UnityEngine;
using System.Collections;

public class cubeCollider : MonoBehaviour
{
	private enum sides{down, up, back, front, left, right};
	Vector3 cubePos, lightPos;
	Transform temp;
	sides checkSides;
	dataManager m_DataManager;
	
	void Start()
	{
		m_DataManager = new dataManager();
		cubePos = m_DataManager.getCubePosition();
		lightPos = m_DataManager.getLightPosition();
	}
	
	void OnCollisionEnter(Collision collision)
	{
		Debug.Log("Cube:" + cubePos);
		Debug.Log("Light: " + lightPos);
	}
}

They are being correctly set in other scripts. Im completely confused as to how these variables only show (0,0,0), yet if I Debug them in the datamanager class before they are returned I get the correct values. What am I doing wrong?

2

Each of your cubeCollider scripts have their own instances of dataManager classes. Is that intentional? Where is the data written to these variables?

private Vector3 d_lightPos, d_cubePos;
3

In the start function
void Start()

{

m_DataManager = new dataManager();

cubePos = m_DataManager.getCubePosition();

lightPos = m_DataManager.getLightPosition();

}

Also it is intentional to have an instance of the datamanager class as I cant see another way of getting that information from that class.

4

Well you could be setting the classes fields before the dataManager’s are being set in another script?

5

OK…could you give an example for that please?

6

What i mean is, your probably setting cubePos and lightPos before another script is setting d_cubePos and d_lightPos.
This can happen, because each script is executed before another, so theres a chance your cubecollider is being run before the on thats seting the values. :slight_smile:
Better?

7

I understand. Thanks :P, I was just wondering if having a datamanager class was the right way to go if i should just store my variables within each class that uses them…

8

Tbh, if alot of classes want to access your dataManager you could just make it a singleton.
Singleton : Singleton pattern - Wikipedia

Heres some code for using a singleton

public class Singleton<T> : MonoBehaviour where T : MonoBehaviour
{
   protected static T instance;
 
   /**
      Returns the instance of this singleton.
   */
   public static T Instance
   {
      get
      {
         if(instance == null)
         {
            instance = (T) FindObjectOfType(typeof(T));
 
            if (instance == null)
            {
               Debug.LogError("An instance of " + typeof(T) + 
                  " could not be found!");
            }
         }
 
         return instance;
      }
   }
}

Now to use this, all you need to do is :

DataManager d = Singleton<DataManager>.Instance;

Hope this helps! :slight_smile:

9

So rather than passing an instance of the class around in parameters, I can use:

DataManager d = Singleton.Instance;

on any script that needs it?

10

Indeed you can :slight_smile:

11

Excellent, ill give it a go! :smile:

12

OK Ive implemented the Singleton class and I get this error:

UnityException: You are not allowed to call this function when declaring a variable.
Move it to the line after without a variable declaration.
If you are using C# don’t use this function in the constructor or field initializers, Instead move initialization to the Awake or Start function.

Should there be a Start or Awake function there?

It refers to this line:

instance = (T) FindObjectOfType(typeof(T));