How to make heart health system?

Questions & Answers
1

Hi everyone! I am trying to make 3 lives for the player, each time a ball hit him, hearts decrease and disappear till the end of the game.
I have two problems:

  1. When the ball hit the player, hearts still remaining no one disappear

  2. I am using LoadLevel, so when some heart disappear it appear again when reloading the level, how to not restore hearts total amount. I tried DontDestroy function, but didn’t work for me.
    Here is few lines of the code

    void CheckHealth() {
    switch (Health) {
    case 3:
    h1.gameObject.SetActive (true);
    h2.gameObject.SetActive (true);
    h3.gameObject.SetActive (true);
    break;
    case 2:
    h1.gameObject.SetActive (true);
    h2.gameObject.SetActive (true);
    h3.gameObject.SetActive (false);
    //Health= PlayerPrefs.SetInt(“Health”, 2);
    break;
    case 1:
    h1.gameObject.SetActive (true);
    h2.gameObject.SetActive (false);
    h3.gameObject.SetActive (false);
    //Health= PlayerPrefs.SetInt(“Health”, 1);
    break;

    		case 0:
			h1.gameObject.SetActive (false);
			h2.gameObject.SetActive (false);
			h3.gameObject.SetActive (false);
			gameover.gameObject.SetActive (true);
			//Health= PlayerPrefs.SetInt("Health", 0);
			Time.timeScale = 0;
			break;
		}

	}


void OnTriggerEnter2D(Collider2D col) {
		
		string[] name = col.name.Split ();
		if (name.Length > 1) {
			if (name [1] == "Ball") {
				Health--;
				CheckHealth ();
					StartCoroutine (KillThePlayer ());

				}
			
			}
		}
2

Hello @m0mohy92,

For your 1st issue ; How are defined h1, h2, h3 ? If those are UI images (attached to an UI canvas) then it should work with “hN.enabled (false);” (remove the “.gameObject”)

For the 2nd issue (passing a variable from scene to scene) you can use DontDestroyOnLoad() as you said, tho you need your script to be either a monobehavior derived class or attached to a gameObject ;

public void Awake()
{
   DontDestroyOnLoad(this.gameObject);
}

Of course if your script is on the player itself and you destroy him when you exit your scene it’s not gonna work (simply put the UI update in another script / on an other empty gameobject)

All in all your script should look like ;

using UnityEngine;
using System.Collections;
using UnityEngine.UI;

// Attach to an empty GameObject
// To initialize script on a new scene, add updateHealthUI() in the Awake or Start Method of your player
// Then just use this script in your OnCollision method using thisScript.Health --
public class UpdateHealthUI : MonoBehaviour // MonoBehaviour
{

// Insert your 3 hearts images in the Unity Editor
[SerializeField] private Image h1, h2, h3;

// Create an array because we're lazy
private Image[] images;

// Gameover
[SerializeField] private Image gameOver;

// A private variable to keep between scenes
[SerializeField] private int health = 3;

// Now we define Get / Set methods for health
// In case we Set health to a different value we want to update UI
public int Health { get { return health; } set { if (health != Health) health = Health;  updateHealthUI(); } }

public void Awake()
{
    DontDestroyOnLoad(this.gameObject);
    images = new Image[] { h1, h2, h3 };
}

private void updateHealthUI()
{
    for(int i = 0; i < images.Length;i++)
    {
        // Hide all images superior to the newHealth
        if (i >= health)
            images*.enabled = false;*

else
images*.enabled = true;*
}
// Game Over
if (health == 0)
{
gameOver.enabled = true; ;
Time.timeScale = 0;
}
}
}

3

You can use void OnSceneLoaded(Scene scene, LoadSceneMode mode) to check when a level is loaded and then call your method CheckHealth(); inside. Note that Health would have to be declared as static so that it’s value persist during change of scenes.

As for why the hearts are not disapearing when a ball hits the player i don’t know, is hard to say by just looking at the piece of code you provided, the best i can say to you is to Debug, see if the object name is actually what you expect and things like that.

For More info on the SceneLoaded callback check:

4

This is a really easy way to do it. If you like, check it out.