"NullReferenceException" while trying to draw a texture (C#)

Question

I'm having a bit of a problem with trying to draw a GUI Texture, I'm trying to draw a lifebar, and the end gets cut off as your health goes down until eventually it, and your health, is nothing.

That's the theory, but like I said, I've come across a problem, I'm getting the "NullReferenceException" error, even though nothing I'm referencing is null, at least not that I know of.

After trial and error, I've concluded that in the draw call, it's the texture part that's causing the problem. I have it set to a public value, so that in the inspector, I can drag and drop the image into the slot. It also means I could reuse the script for other GUI/HUD Bars, which would really save me time in the long run, so I really hope this isn't the problem.

Here's my code:

     public enum BarType
     {
         Health = 0,
         Armour = 1,
         Power = 2
     }
     public BarType barType;
     public Texture texture;
     public GameManager masterScript;
     private float health;
     
     void Update () 
     {
         if (barType == BarType.Health)
         {
             health = (masterScript.health / masterScript.maxHealth);
         }
         else
         {
         }
         GUI.DrawTextureWithTexCoords(new Rect(0, 0, 1, 1)
             , texture, new Rect(0,0, 1, health), false);
     }

How do I fix this?

Answer 1

Best Answer

Answer by paulaceccon · Feb 03, 2013 at 12:07 PM

Have you tried to put this

 GUI.DrawTextureWithTexCoords(new Rect(0, 0, 1, 1), texture, new Rect(0,0, 1, health), false);

inside the OnGUI function, instead of in the Update??

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Cobradabest · Feb 03, 2013 at 12:14 PM 0

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Oh yeah, that's right, there's an "OnGUI" function.

It's not any errors anymore but nothing's showing up now, what could cause that?

paulaceccon · Feb 03, 2013 at 12:22 PM 0

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Reading you question, I didn't find something that could cause this. Can you test this code below?

    public enum BarType
    {
        Health = 0,
        Armour = 1,
        Power = 2
     }
     public BarType barType;
     public Texture texture;
     public GameManager masterScript;
     private float health;
  
    void Awake ()
    {
         texture =  Resources.Load("yourtexturename") as Texture;
    }
 
     void Update () 
     {
        if (barType == BarType.Health)
        {
          health = (masterScript.health / masterScript.maxHealth);
        }
        else
        {
        }
     }
 
 void OnGUI ()
 {
    if (texture)
         GUI.DrawTextureWithTexCoords(new Rect(0, 0, 1, 1)
          , texture, new Rect(0,0, 1, health), false);
 
    else
      Debug.Log("texture not found");
 }

You just have to create a Resources folder and put your texture there. Another thing, if this condition

  if (barType == BarType.Health)
  {
       health = (masterScript.health / masterScript.maxHealth);
  }

didn't apply, what is the health value?

Cobradabest · Feb 03, 2013 at 12:28 PM 0

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I'm not too into the idea of using "Resources.Load", because that would mean the script would be exclusive to that texture, and I don't want that, I have other bars in the game, and using the same script for all of them would really save me trouble.

paulaceccon · Feb 03, 2013 at 12:35 PM 0

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I see, I'm just trying to figure out if Unity is finding your texture. Have you put some Debug.Log s to see if the texture was found?

Cobradabest · Feb 03, 2013 at 12:43 PM 0

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Alright, I've tried the code anyway, and I'm afraid it didn't make a difference.

After taking the "Resources.Load" line out, I decided to test it again, I would expect it to log that the texture is missing, and that's what it did, so it's definetly accessing the function, it's not drawing anything when there IS a texture.

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"NullReferenceException" while trying to draw a texture (C#)

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