Question Unity Learn | Trouble setting up my score tracking system

Hi ! I started the Unity Learn Junior Programmer Pathway a few days ago, and I'm at the Basic Gameplay prototype bonus features where we have to setup a lives and score system.
I made a MechanicsManager script attached to a game object of the same name, and inside put this code:

public class MechanicsManager : MonoBehaviour
{
private GameObject[] animals;
//[HideInInspector]
public int score = 0;
private int lives = 3;

// Start is called before the first frame update
void Start()
{
Debug.Log("Lives left: " + 3);
}

// Update is called once per frame
void Update()
{
animals = GameObject.FindGameObjectsWithTag("Animal");
foreach(GameObject animal in animals)
{
if (animal.transform.position.x < -21 || animal.transform.position.x > 21 || animal.transform.position.z < -3)
{
Destroy(animal);
score -= 1;
Debug.Log("Score: " + score);
}
/*if(animal.GetComponent<DetectCollisions>().hit == true)
{
score += 1;
Debug.Log("Score: " + score);
}*/

}
}
}

For the score incrementation, I wanted to use the DetectCollisions script to add to the score directly in it when I hit an animal with my projectile:

public class DetectCollisions : MonoBehaviour
{
//public bool hit = false;
public GameObject manager;

// Start is called before the first frame update
void Start()
{
Time.timeScale = 1;
}

// Update is called once per frame
void Update()
{

}

public void OnTriggerEnter(Collider other)
{
switch(other.tag)
{
case "Sandwich":
manager.GetComponent<MechanicsManager>().score += 1;
//hit = true;
Debug.Log("hit an enemy");
Destroy(other.gameObject);
Destroy(gameObject);
break;
case "Player":
Time.timeScale = 0;
Debug.Log("Game Over !");
break;
}

}
}

I tried to reference the other script, but I can't drag it from the MechanicsManager game object from the hierarchy to the Inspector on the animals prefabs.
You can also see that I tried the other way around where I use a boolean to tell if the player hits an animal, but I think the animal gets destroyed too quick for the other script to read the boolean value.

Any help resolving this ? Either by letting the other script read the hit boolean value, or by being able to increment the score variable directly from the DetectCollisions script (that would be the best).

 

You can never drag an in-scene object into an asset. This is because scenes are just transient.

It sounds like you've got something slightly mixed up in the tutorial. This is fairly common because it can be confusing if you're mixing and matching assets and scenes.

This approach can help you untangle it:

Tutorials and example code are great, but keep this in mind to maximize your success and minimize your frustration:

How to do tutorials properly, two (2) simple steps to success:

Step 1. Follow the tutorial and do every single step of the tutorial 100% precisely the way it is shown. Even the slightest deviation (even a single character!) generally ends in disaster. That's how software engineering works. Every step must be taken, every single letter must be spelled, capitalized, punctuated and spaced (or not spaced) properly, literally NOTHING can be omitted or skipped.

Fortunately this is the easiest part to get right: Be a robot. Don't make any mistakes.
BE PERFECT IN EVERYTHING YOU DO HERE!!

If you get any errors, learn how to read the error code and fix your error. Google is your friend here. Do NOT continue until you fix your error. Your error will probably be somewhere near the parenthesis numbers (line and character position) in the file. It is almost CERTAINLY your typo causing the error, so look again and fix it.

Step 2. Go back and work through every part of the tutorial again, and this time explain it to your doggie. See how I am doing that in my avatar picture? If you have no dog, explain it to your house plant. If you are unable to explain any part of it, STOP. DO NOT PROCEED. Now go learn how that part works. Read the documentation on the functions involved. Go back to the tutorial and try to figure out WHY they did that. This is the part that takes a LOT of time when you are new. It might take days or weeks to work through a single 5-minute tutorial. Stick with it. You will learn.

Step 2 is the part everybody seems to miss. Without Step 2 you are simply a code-typing monkey and outside of the specific tutorial you did, you will be completely lost. If you want to learn, you MUST do Step 2.

Of course, all this presupposes no errors in the tutorial. For certain tutorial makers (like Unity, Brackeys, Imphenzia, Sebastian Lague) this is usually the case. For some other less-well-known content creators, this is less true. Read the comments on the video: did anyone have issues like you did? If there's an error, you will NEVER be the first guy to find it.

Beyond that, Step 3, 4, 5 and 6 become easy because you already understand!

Finally, when you have errors, don't post here... just go fix your errors! Here's how:

Remember: NOBODY here memorizes error codes. That's not a thing. The error code is absolutely the least useful part of the error. It serves no purpose at all. Forget the error code. Put it out of your mind.

The complete error message contains everything you need to know to fix the error yourself.

The important parts of the error message are:

- the description of the error itself (google this; you are NEVER the first one!)
- the file it occurred in (critical!)
- the line number and character position (the two numbers in parentheses)
- also possibly useful is the stack trace (all the lines of text in the lower console window)

Always start with the FIRST error in the console window, as sometimes that error causes or compounds some or all of the subsequent errors. Often the error will be immediately prior to the indicated line, so make sure to check there as well.

Look in the documentation. Every API you attempt to use is probably documented somewhere. Are you using it correctly? Are you spelling it correctly?

All of that information is in the actual error message and you must pay attention to it. Learn how to identify it instantly so you don't have to stop your progress and fiddle around with the forum.

If you want to debug it yourself, here's how:

Time to start debugging! Here is how you can begin your exciting new debugging adventures:

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

Once you understand what the problem is, you may begin to reason about a solution to the problem.

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
- you're getting an error or warning and you haven't noticed it in the console window

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 names of the GameObjects or Components involved?
- 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 supply a second argument to Debug.Log() and when you click the message, it will highlight the object in scene, such as

Debug.Log("Problem!",this);

If your problem would benefit from in-scene or in-game visualization, Debug.DrawRay() or Debug.DrawLine() can help you visualize things like rays (used in raycasting) or distances.

You can also call Debug.Break() to pause the Editor when certain interesting pieces of code run, and then study the scene manually, looking for all the parts, where they are, what scripts are on them, etc.

You can also call GameObject.CreatePrimitive() to emplace debug-marker-ish objects in the scene at runtime.

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

Visit Google for how to see console output from builds. If you are running a mobile device you can also view the console output. Google for how on your particular mobile target, such as this answer for iOS: https://forum.unity.com/threads/how-to-capturing-device-logs-on-ios.529920/ or this answer for Android: https://forum.unity.com/threads/how-to-capturing-device-logs-on-android.528680/

If you are working in VR, it might be useful to make your on onscreen log output, or integrate one from the asset store, so you can see what is happening as you operate your software.

Another useful approach is to temporarily strip out everything besides what is necessary to prove your issue. This can simplify and isolate compounding effects of other items in your scene or prefab.

If your problem is with OnCollision-type functions, print the name of what is passed in!

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://forum.unity.com/threads/coroutine-missing-hint-and-error.1103197/#post-7100494

"When in doubt, print it out!(tm)" - Kurt Dekker (and many others)

Note: the

print()

function is an alias for Debug.Log() provided by the MonoBehaviour class.

 

That makes sense. I have done many dragging before tho, so Im not sure why Im struggling so much here.

I don't have any errors btw, just the one saying that the manager variable isn't set (because I couldn't drag the game object).
The tutorial, because it's bonus features, doesn't have any clues or code, just a goal, so it couldn't have any error.

I do try to think about solutions myself; I just break down what I want to achieve into simple instructions, then search how I could do it; I read the documentation and Google if I don't find my answer. I've just been at it for 2 days and thought I'd ask here to see if someone could help with the way I wanted to code it.

I haven't looked at the tutorial comments since I don't think they're using the same method, but I'll do it eventually to see the different ways they've achieved it.

The differents Debug methods are nice, thx!

 

You can drag-and-drop a reference from one instance to another just fine. You cannot, however, reference an instance in a prefab.

• Prefabs: Exist in your project folder, and can be dragged-and-dropped into (or instantiated in) scenes, at which point they appear in the Hierarchy as...
• Instances: Copies of a prefab that exist inside a scene.

It's important to be able to make this distinction, otherwise you'll continue to be very confused.

Unlike scenes, which are never guaranteed to be loaded at any given time, prefabs are always there just like images or even audio files you've imported. This is why it makes sense that you can't reference an instance inside a prefab.

The problem you're stuck with right now is basically: if I can't drag-and-drop a scene/instance reference onto my prefab, then how the heck do I even acquire that reference?

The answer is... well, there are loads of different ways!