Dynamically changing sprites at runtime

Unity Engine
,
1

Im sure this is a novice question, so please bear with me. I am looking to change a “Healthbar” at runtime depending on the condition of the player. As a simple test case, I just want to show a bar with no “life” when the character is dead.

Ive tried a few different methods and am not able to change the existing full health bar to another sprite upon character death. This is what I got so have so far.

public class Player : MonoBehaviour
{
  

    public int maxHealth = 3;
    public int currentHealth = 3;
    public int currentSpeed = 5;
   

    public int currentScore = 0;

    public Sprite Dead; // Assets/Sprites/Powerups/Health/No Health/Dead.png

  
    public void OnDamage()
    {
        currentHealth--;
        Debug.LogFormat("The player's current health is: {0}", currentHealth);

        if (currentHealth == 0)
        {
            Dead = Resources.Load<Sprite>("Dead");
            GameObject.Find("HealthBar").GetComponent<SpriteRenderer>().sprite = Dead;
            OnDeath();
        }
    }

    public void OnDeath()
    {
        Debug.Log("You're dead!");
        Time.timeScale = 0;
    }

}

I know this is probably a simple fix, but I can’t wrap my head around it just yet. Thanks for any help in advance.

2

You must find a way to get the information you need in order to reason about what the problem is.

What is often happening in these cases is one of the following:

  • the code you think is executing is not actually executing at all
  • the code is executing far EARLIER or LATER than you think
  • the code is executing far LESS OFTEN than you think
  • the code is executing far MORE OFTEN than you think
  • the code is executing on another GameObject than you think it is

To help gain more insight into your problem, I recommend liberally sprinkling Debug.Log() statements through your code to display information in realtime.

Doing this should help you answer these types of questions:

  • is this code even running? which parts are running? how often does it run? what order does it run in?
  • what are the values of the variables involved? Are they initialized? Are the values reasonable?
  • are you meeting ALL the requirements to receive callbacks such as triggers / colliders (review the documentation)

Knowing this information will help you reason about the behavior you are seeing.

You can also put in Debug.Break() to pause the Editor when certain interesting pieces of code run, and then study the scene

You could also just display various important quantities in UI Text elements to watch them change as you play the game.

If you are running a mobile device you can also view the console output. Google for how on your particular mobile target.

Here’s an example of putting in a laser-focused Debug.Log() and how that can save you a TON of time wallowing around speculating what might be going wrong:

https://discussions.unity.com/t/839300/3

Also, don’t write hairy gnarly code like this: (Technically it may be 100% correct. Maintainability-wise, it is 0% correct).

How to break down hairy lines of code:

http://plbm.com/?p=248

Break it up, practice social distancing in your code, one thing per line please.

ALSO!! Even more importantly,

Remember the first rule of GameObject.Find():
Do not use GameObject.Find();
More information: https://starmanta.gitbooks.io/unitytipsredux/content/first-question.html

3

put more debug logs, check if dead becomes the correct sprite in the inspector, then check if game object find is finding the correct component

4

I figured it out, implemented some of the advice, thank you for the feedback and the assistance

1 Like