How to SetActive or enable a Canvas attached to prefabs that get instantiated (tower defense style)?

Question

I am back again after making much progress in quest for unity and c# knowledge. I have become stumped yet again by how to enable a canvas that is attached to my prefab. Here is the situation:

I am using C# on unity 5.5.0f3.

I have UI buttons that instantiate a defense based on a prefab. That prefab has a Canvas attached to it which has a health bar attached to it. Currently, the canvas is disabled so that the health bar does not show at all times. I am trying to make it appear only when I hold down a button, in this case "Z", and disappear when I release Z. My code is letting this work if I place a prefab before hand and set the GameObject reference in the editor. I want to get it to work for any object that has this canvas attached to it. This code does not work for all of the prefabs even if I take the canvas from the prefab and make it the reference.

I have tried to use an array like I have with other things that are currently working, but it does not work the same.

Here is my code:

public class DefenseHealthToggle : MonoBehaviour
{
public GameObject defenseHealthBars;
private bool isShowing;



void Update()
{
    if (Input.GetKeyDown(KeyCode.Z))
    {
        isShowing = !isShowing;
        defenseHealthBars.SetActive(isShowing);
    }

    if (Input.GetKeyUp(KeyCode.Z))
    {
        isShowing = false;
        defenseHealthBars.SetActive(isShowing);
    }
}
}

While this is a minor detail in the game, I am trying to not let any of the ideas go if it is because I could just not figure out how to do it. I think I will learn the most if I don't give up every time I hit a wall and so far it has improved my knowledge tremendously! Anyone point me in the right direction or help me with some code? Thank you for your time!

Answer 1

You can leave the Canvas or object active initially and grab it using transform.find("nameofobject") in the start.

Then you can set active or inactive whenever you want. using defenseHealthBars.SetActive(true);

public class DefenseHealthToggle : MonoBehaviour
{
 private GameObject defenseHealthBars;
 private bool isShowing;

void Start(){
 defenseHealthBars = transform.Find("NameofObject").gameObject as GameObject;
 defenseHealthBars.SetActive(false);
}

 void Update()
{
    if (Input.GetKeyUp(KeyCode.Z))
    {     
        ToggleHealthBars();
    }    
}
void ToggleHealthBars()
{
    defenseHealthBars.SetActive(!defenseHealthBars.activeSelf);
}

Answer 2

I suggest you to automate the procedure like doing the following:

• Instead of having defenseHealtBars as public, make it private, you can use [SerializeField] if you want to have it visible in the editor anyways.
• Find the relevant canvas component (with GetComponent() or GetComponentInChildren(), depends where you placed the canvas object) in the DefenseHealthToggle script's void Start() method.
• Log an error if the script cannot find the object you want to control (enable/disable).

Also do not forget to type using UnityEngine.UI;