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Bug Simple Operators Yields Different Results in Editor and in Build

Discussion in 'Editor & General Support' started by yoavtc2004, Nov 11, 2023.

  1. yoavtc2004

    yoavtc2004

    Joined:
    Jan 17, 2023
    Posts:
    10
    I have these simple lines of code:

    Code (CSharp):
    1.     [SerializeField] [ReadOnly] private int healthPoints = 3;
    2.  
    3.     public int health => healthPoints;
    4.  
    5.     public void RestartGame()
    6.     {
    7.         healthPoints = 3;
    8.     }
    9.     private void Start()
    10.     {
    11.         healthPoints = 3;
    12.     }
    13.  
    14.     public void OnDamage()
    15.     {
    16.         healthPoints--;
    17.         if (health <= 0)
    18.         {
    19.             KillPlayer();
    20.         }
    21.     }
    Nothing else in the project is changing the healthPoints variable. When I run it in the editor, when the player is on 1hp (before the subtraction in line 16) and then takes damage, they die and trigger the KillPlayer() function.

    But when I build my game, it's like it changes the <= operator to <. It only triggers the kill function when the player has 0hp (before the subtraction in line 16).

    Anyone experienced this before? Again, nothing else in the code is messing with these variables.
     
  2. Kurt-Dekker

    Kurt-Dekker

    Joined:
    Mar 16, 2013
    Posts:
    38,338
    Any reason you're doing all that crazy CIS-100 complexity??

    This enormously incomprehensible blob:

    can simply be done:

    Code (csharp):
    1. public int health;   /// DO NOT set the value here in the field initializer. Read below for why
    and be done with.

    Set it when you restart and move on.

    Once you have 100% of everything working perfectly, break out your CIS-100 textbooks and go back and do what you like with getters and setters and decorators and whatnot, but don't handicap yourself with unnecessary visual noise and complexity!



    Execution order can vary.

    Here is some timing diagram help:

    https://docs.unity3d.com/Manual/ExecutionOrder.html


    To see the order things are running...

    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

    If you are looking for how to attach an actual debugger to Unity: https://docs.unity3d.com/2021.1/Documentation/Manual/ManagedCodeDebugging.html

    "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.



    ---------------

    Serialized / public fields in Unity are initialized as a cascade of possible values, each subsequent value (if present) overwriting the previous value:

    - what the class constructor makes (either default(T) or else field initializers, eg "what's in your code")

    - what may be saved with the prefab

    - what may be saved with the prefab override(s)/variant(s)

    - what may be saved in the scene and not applied to the prefab

    - what may be changed in the scene and not yet saved to disk

    - what may be changed in OnEnable(), Awake(), Start(), or even later

    Make sure you only initialize things at ONE of the above levels, or if necessary, at levels that you specifically understand in your use case. Otherwise errors will seem very mysterious.

    Here's the official discussion: https://blog.unity.com/technology/serialization-in-unity

    If you must initialize fields, then do so in the void
    Reset()
    method, which ONLY runs in the UnityEditor.

    Field initializers versus using Reset() function and Unity serialization:

    https://forum.unity.com/threads/sensitivity-in-my-mouselook-script.1061612/#post-6858908

    https://forum.unity.com/threads/crouch-speed-is-faster-than-movement-speed.1132054/#post-7274596

    To avoid complexity in your prefabs / scenes, I recommend NEVER using the
    FormerlySerializedAsAttribute
     
    Last edited: Nov 11, 2023
  3. APSchmidt

    APSchmidt

    Joined:
    Oct 31, 2023
    Posts:
    252
    Shouldn't it be:

    Code (CSharp):
    1. health--;
    ?
     
  4. CodeSmile

    CodeSmile

    Joined:
    Apr 10, 2014
    Posts:
    5,129
    Naming conventions!

    A property should have the same name as its backing field. A backing field should have a prefix. Variables should be camel case.

    For example, this is what Unity seems to be using internally for the past couple years (with exceptions):

    private int m_HealthPoints;
    public int HealthPoints => m_HealthPoints;


    Then it becomes obvious that this code is a little 'off':
    Code (CSharp):
    1.     public void OnDamage()
    2.     {
    3.         m_HealthPoints--;
    4.         if (HealthPoints <= 0)
    5.         {
    6.             KillPlayer();
    7.         }
    8.     }
    There is no reason for the internal code to use the property rather than the field.

    You are contradicting your own observation.

    This statement: "It only triggers the kill function when the player has 0hp"
    Expressed in code: if (HealthPoints == 0) // when player has 0 hp
    But operator changes from <= to < ('less'): if (HealthPoints < 0)

    So what is it?

    In any case:
    There's a debugger in your IDE. Attach it, set a breakpoint, step through lines of code as they execute, and inspect any variable in scope. Imagine how useful that is! ;)
     
  5. yoavtc2004

    yoavtc2004

    Joined:
    Jan 17, 2023
    Posts:
    10
    I'll try to rename my public and private health variables, but I thought it shouldn't matter should it?