Can You Convert a Transform into an Image?

[George-B]

Hello! I am making a video game, where the player moves around the screen and presses the space bar to fire harpoons at fish. Each fish has a health bar, and I want to access the fill amount of the health bar when the harpoon touches the fish.

I have tried to access the health bar child of the fish, but I keep getting errors. What is the correct way to access a child (specifically an Image) of a parent GameObject. How do I change its fillAmount? Thanks in advance- George

Here is my code-

harpoonScript

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

public class harpoonScript : MonoBehaviour {

// Public variable 
public int speed = 6;
private Rigidbody2D r2d;
public Text FishLabel;
public int fishKillCount = 0;

public Transform fishBar;
public Image fishBarFill;

// Function called once when the bullet is created
void Start () {
    // Get the rigidbody component
    r2d = GetComponent<Rigidbody2D>();

    // Make the bullet move upward
    float ySpeed = 0;
    float xSpeed = -8;

    Vector2 newVelocity = new Vector2(xSpeed, ySpeed);
r2d.velocity = newVelocity;

}

void OnTriggerEnter2D(Collider2D other) //hero hits side of enemy
    {

      fishBar = this.gameObject.transform.GetChild(3);
      fishBarFill = fishBar;

      if (fishBar.fillAmount > 0) {

        fishBar.fillAmount = fishBar.fillAmount - 0.5;
  }

  else {
    string fishStringfromText = FishLabel.text;
             int fishIntfromText;
             fishIntfromText = int.Parse(fishStringfromText);

  ++fishIntfromText;

  FishLabel.text = fishIntfromText.ToString();

       Debug.Log("GameObject found, reference is not null");
       Destroy(other.gameObject.GetComponent<Collider2D>()); //Remove collider to avoid audio replaying
            other.gameObject.GetComponent<Renderer>().enabled = false; //Make object invisible
            Destroy(other.gameObject, 0.626f); //Destroy object when audio is done playing, destroying it before will cause the audio to stop
    Destroy(GameObject.Find("harpoon_00001(Clone)"));
  }
}

}

PS- Sorry if my question is too vague, or you don’t have enough information. Just tell me, and I can add more to my question

[josehzz112]

Hello I think I spot some errors, lets go step by step.

1. Make sure that the Image component you want to access has Image Type = Filled on the Inspector.
2. You are getting a Transform component and saving that on an Image variable. (First error).
3. Because fishBar is a Transform variable it doesn’t have a fillAmount parameter. (Second error).

Here’s the fixed code, make sure you have everything assigned on the inspector before running it.

using UnityEngine;
using System.Collections;
using UnityEngine.UI;
 
public class harpoonScript : MonoBehaviour {
 
// Public variable 
public int speed = 6;
private Rigidbody2D r2d;
public Text FishLabel;
public int fishKillCount = 0;
 
public Transform fishBar;
public Image fishBarFill;
 
// Function called once when the bullet is created
void Start () {
     // Get the rigidbody component
     r2d = GetComponent<Rigidbody2D>();
 
     // Make the bullet move upward
     float ySpeed = 0;
     float xSpeed = -8;
 
     Vector2 newVelocity = new Vector2(xSpeed, ySpeed);
     r2d.velocity = newVelocity;
 }
 
void OnTriggerEnter2D(Collider2D other) //hero hits side of enemy
{
       fishBarFill = this.gameObject.transform.GetChild(3).GetComponent<Image>();
 
       if (fishBarFill.fillAmount > 0) {
         fishBarFill.fillAmount = fishBarFill.fillAmount - 0.5;
       }
       else {
         string fishStringfromText = FishLabel.text;
         int fishIntfromText;

         fishIntfromText = int.Parse(fishStringfromText);
         ++fishIntfromText;
 
         FishLabel.text = fishIntfromText.ToString();
 
        Debug.Log("GameObject found, reference is not null");
        Destroy(other.gameObject.GetComponent<Collider2D>()); //Remove collider to avoid audio replaying
        other.gameObject.GetComponent<Renderer>().enabled = false; //Make object invisible
        Destroy(other.gameObject, 0.626f); //Destroy object when audio is done playing, destroying it before will cause the audio to stop
        Destroy(GameObject.Find("harpoon_00001(Clone)"));
        }
 }
 }

[smnerat]

You didn’t post the error so I’m not sure what your problem is, but I would guess its due to several misunderstanding at line 33.

At line 33, you are trying to get the health bar, which is an image, by searching for a transform as if it were the child of the harpoon, not the fish.

With that said, to get the transform itself, try this:

void OnTriggerEnter2D(Collider2D other) { 
       fishBar = other.transform.GetChild(3);

       etc.....
}

Now you should have a reference to the transform that has an Image component on it, but you still need to access the actual Image component before you can do anything.

void OnTriggerEnter2D(Collider2D other) { 
       fishBar = other.transform.GetChild(3);
       fishBarFill = fishBar.gameObject.getComponent<Image>();

       fishBarFill.fillAmount = 0.5f;
}

This general concept applies to pretty much everything in Unity. First, get a reference to the transform or gameObject that the component is on. Then get whatever component you need (transform, collider, material, renderer, script, text, etc).