I’m trying to add a score counter to my game and I’m using the one from the unity roll a ball tutorial since it seemed pretty simple. I’m also using the same compare tag code that the tutorial used to increase the count but not to destroy the other objects since I’m using code from a different tutorial for that already. I ended up putting the score code in a separate script since I’m following two tutorials at the same time so it seemed easier than putting it in the player controller script. I’ve also already added the TextMeshProUGUI to the script in the inspector but when an enemy dies it does not increase the count and just gives me the error mentioned above and I’m not sure why since I did add the TextMeshProUGUI to the code in the inspector. Here is the code I am using:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using TMPro;
public class Count : MonoBehaviour
{
private int count;
public TextMeshProUGUI countText;
// Start is called before the first frame update
void Start()
{
count = 0;
SetCountText();
}
// Update is called once per frame
void Update()
{
}
private void OnTriggerEnter(Collider other)
{
if (other.gameObject.CompareTag("Animal"))
{
count = count + 1;
SetCountText();
}
}
void SetCountText()
{
countText.text = "Count: " + count.ToString();
}
}
And a screenshot of the inspector window is attatched.
Would help to know where the error is occuring (as in post the full error, otherwise we’re shooting in the dark).
I would also use the second overload of Debug.Log that pings the object that fired the error. Of these “I assigned it but there’s still a null-ref” error is because there’s an instance of a component somewhere in a scene that you forgot about, where you haven’t assigned anything to.
Oh gosh don’t use string.Format. The solution to fixing bugs is not to guess until it goes away but to “reason” the cause, test that theory and then to fix the actual problem.
A simply log line would indicate that reference is null. count isn’t a reference it can’t be null.
I assume you mean the countText object. I dragged the script onto one of my objects and I added the Text Mesh Pro UGUI object to the script in the inspector. I added a screenshot of the inspector window where I did this in my original post.
Using a string.Format generate less garbage using zString with format is even better. Just writing as a “normal string” value and declaring ToString will increase it significantly it’s a good purpose at least to learn that. If you trigger every time that enemy is died from OnTriggerEnter make it even worse since it keep regenerate it each time.
Update: I just saw that the error is coming from the fact that the script IS attached to the game object in the scene but NOT to the prefab I’m using to spawn new items whenever the player presses space. This means that the object doesn’t have the Text Mesh Pro UGUI attached to it when new ones spawn. BUT unfortunately things aren’t completely solved. For some reason even though I can attach the text object to the game object in the script, I can’t attach it to the prefab for some reason and I’m not sure why since the game object is a copy of the prefab and the script is the exact same.
In my previous post I just said what was null. To use your formula, here is where I’m at now:
-Identify what is null ← The count text object in the prefab of the game object.
-Identify why it is null ← Because I can’t add the Text Mesh Pro UGUI object to the prefab like with the individual game object
-Fix that ← I don’t know how.
The first attached picture shows that I can and have added the text object to the game object in the scene and the second shows that I can’t add it to the prefab even though it is the same object and the same script.
You have dragged in one food pizza copy into your scene.
The CountText looks like it is simply in your scene as a Canvas UI hierarchy.
And this is the important part:
A prefab on disk could NEVER reference ANYTHING live in a scene.
You CAN drag that text object into the in-scene instance of the prefab, but it could NEVER be saved into the prefab and would ALWAYS be a single overload on this one single pizza lying in your scene.
REMOVE the pizza from your scene to REMOVE this temptation.
Make your pizza spawner either inject the necessary data into the pizza objects when it spawns or else…
The typical construct in Unity is to make a GameManager or perhaps a ScoreManager that is in charge of tallying score.
Your food pizza would locate that object (there are many ways, read below) and add to the score.
ULTRA-simple static solution to a GameManager:
OR for a more-complex “lives as a MonoBehaviour or ScriptableObject” solution…
Simple Singleton (UnitySingleton):
Some super-simple Singleton examples to take and modify:
Simple Unity3D Singleton (no predefined data):
Unity3D Singleton with a Prefab (or a ScriptableObject) used for predefined data:
These are pure-code solutions, DO NOT put anything into any scene, just access it via .Instance
Alternately you could start one up with a RuntimeInitializeOnLoad attribute.
The above solutions can be modified to additively load a scene instead, BUT scenes do not load until end of frame, which means your static factory cannot return the instance that will be in the to-be-loaded scene. This is a minor limitation that is simple to work around.
If it is a GameManager, when the game is over, make a function in that singleton that Destroys itself so the next time you access it you get a fresh one, something like:
public void DestroyThyself()
{
Destroy(gameObject);
Instance = null; // because destroy doesn't happen until end of frame
}
There are also lots of Youtube tutorials on the concepts involved in making a suitable GameManager, which obviously depends a lot on what your game might need.
OR just make a custom ScriptableObject that has the shared fields you want for the duration of many scenes, and drag references to that one ScriptableObject instance into everything that needs it. It scales up to a certain point.
And finally there’s always just a simple “static locator” pattern you can use on MonoBehaviour-derived classes, just to give global access to them during their lifecycle.
WARNING: this does NOT control their uniqueness.
WARNING: this does NOT control their lifecycle.
public static MyClass Instance { get; private set; }
void OnEnable()
{
Instance = this;
}
void OnDisable()
{
Instance = null; // keep everybody honest when we're not around
}
Anyone can get at it via MyClass.Instance., but only while it exists.
You see the line number right? There is only one object on line 36 so surely that is null.
