Unity-Sharing values between functions invoked by buttons and the rest of the script [closed]

Question

Ok so, here is the problem.

I am doing a multiplayer 2D game using UNET.

I have a script that kind of helps a player select an avatar to play with. The avatars are listed as a scrollview of buttons. These buttons invoke the function setAvatar(int id) that sets a player's avatar passing in an ID as argument. The function just sets the player's avatar using ID as index in a list of avatars.

Now the problem is this player is a prefab which is instantiated at the start of the playscene for Player A and Player B. So the setAvatar(int sprid) function assumes I am referring to the prefab whenever I use "gameObject"

So, I decided to store the local gameObject in a temporary variable.

Here's the full code,

public class Player2DController : NetworkBehaviour // Attached to player prefab
{
    public float moveForce = 2;
    Rigidbody2D myBody;
    Transform mainCamera;
    Shooting shscript;
    int i;
    public Transform joystick;
    GameObject temp;

    public Sprite[] spr;

    void Start ()
    {
        if (!isLocalPlayer) 
        {
            Destroy (this);
            return;
        }

        temp = gameObject; // storing local gameobject in temp

        joystick = GameObject.Find ("MobileJoystick").transform;
        shscript = GetComponent<Shooting> ();
        mainCamera = Camera.main.transform;
        RotateCamera ();
        myBody = GetComponent<Rigidbody2D> ();

        if (isClient) 
        {
            i = -1;
        }
        if (isServer) 
        {
            i = 1;
        }

    }



    public void RotateCamera()
    {
        if (isClient)
        {
            mainCamera.rotation = Quaternion.Euler (new Vector3 (0f, 0f, 180f));
        }
        if (isServer) 
        {
            mainCamera.rotation = Quaternion.Euler (new Vector3 (0f, 0f, 0f));
        }
    }

    void FixedUpdate ()
    {
        if (PauseMenu.isOn) 
        {
            return;
        }
        Vector2 moveVec = new Vector2(CrossPlatformInputManager.GetAxis("Horizontal"),CrossPlatformInputManager.GetAxis("Vertical"))* moveForce;

        myBody.AddForce (moveVec * i);

        if (CrossPlatformInputManager.GetButton("Shoot"))
        {
            shscript.CmdFire ();
        }

    }


    public void setAvatar(int id) // called through the buttons in the avatar list
    {
        temp.GetComponent<SpriteRenderer> ().sprite = spr [id];//null pointer exception
    }
}

This code doesn't work. I get a null pointer exception on temp variable saying it is not assigned. But how can this be? I clearly assign it to active gameObject in Start() method. The only reason I can think of why this is happening is that since the button acts on the player prefab, it creates a separate instance of the script for the player prefab that doesn't get executed. So, when it invokes setAvatar(), it has a temp which is not initialized.

So that's the whole problem. Since this didn't work, I tried renaming the players as clientPlayer and serverPlayer and then accessing them using GameObject.Find(name).GetComponent<SpriteRenderer>().sprite. But this had no effect and no errors. I have no idea why.

So any ideas on how to go about this?

Answer 1

It might be the case that the following part get executed and temp is never assigned to gameObject:

if (!isLocalPlayer) 
{
    Destroy (this);
    return;
}

So make sure that you check for null before utilising this reference:

if(temp != null)
    temp.GetComponent<SpriteRenderer> ().sprite = spr [id];