Question Flappy question

I'm trying to make a flappy bird type game. It's going well so far, except that I need my bird to die when it touches the borders of the camera.

So I put this:

Code (CSharp):

1.  public Vector2 cameraBounds = Camera.main.ScreenToWorldPoint(new Vector3(Screen.width, Screen.height, Camera.main.transform.position.z));

And then this on update:

Code (CSharp):

1. {
2.             if (transform.position.y > cameraBounds.y || transform.position.y < -cameraBounds.y)
3.  
4.                 logic.gameOver();        
5. }

It shows no compiler errors in visual studio but on Unity, it says "get_main is not allowed to be called from a MonoBehaviour constructor (or instance field initializer), call it in Awake or Start instead." I am really lost lol

 

EDIT: re-reading your error, as @halley points out below, you need to move the Unity API calls out of the field initializer. See Halley's post.

The reason: field initializers for Unity objects (such as MonoBehaviour) do not happen on the main thread, meaning that Unity API calls are off-limits in field initializers.

Sounds like it is ....

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 or 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.

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.

 

you should post the whole script and the whole error but there is already a fail in your logic

the points to die should be

Code (CSharp):

1. float upperBoundY = Camera.ScreenToWorldPoint(new Vector3(0, Screen.height, 0)).y;
2.  
3. float lowerBoundY = Camera.ScreenToWorldPoint(new Vector3(0, 0, 0)).y;

 

The code in your first snippet is called an instance field initializer. You're creating a field (a variable belonging to an instance of an object) called

cameraBounds

, and you're initializing it with a value (the expression

Camera.main.blahblah

).

The error message is saying you can't do something in an instance field initializer. It's not at all obvious to newcomers, but when you reference

Camera.main

, that is really doing something nontrivial behind the scenes, and it's not allowed in an instance field initializer.

Replace the first snippet with

Code (CSharp):

1. public Vector2 cameraBounds;
2.  
3. public void Start()
4. {
5.     cameraBounds = Camera.main.ScreenToWorldPoint(
6.         new Vector3(Screen.width, Screen.height,
7.                     Camera.main.transform.position.z));
8. }

That should satisfy the error message, since it's the approach which the message is recommending.

 

You absolutely got me there. I was scanning it too fast. I did not see the ctor() error OP wrote.