Develop Reference

Variable not being set in class using inheritance

Edit: It turns out it was how I was getting the ProjectileWeapon component. I was getting the one that was on the non-instantiated prefab instead of getting the one on weapon gameobject. I changed it so that the code instantiates the game object first (or gets the existing one if we've already picked it up), and then get the component from that. So the rest of the code works fine. Now I can move on and improve it!
I have an issue with the class below called ProjectileWeapon. It is based on an abstract class called Weapon, and that class inherits MonoBehaviour.
Weapon has two abstract functions called BeginCycle and EndCycle which are implemented in the ProjectileWeapon class. Those functions set a variable called "firing".
The problem is, "firing" doesn't ever seem to be set despite the functions being called correctly. I know the functions are called because I can see the prints in the console.
Also, when I use that variable in the update function, it doesn't do anything because the variable never changes.
The OnGUI function is working and is displaying text on screen, however the "firing" variable is never updated.
Am I misunderstanding how to use inheritance?
This class is on the weapon prefab which is then instantiated during the equipping function in the game
public class ProjectileWeapon : Weapon
{
private bool firing;
private float firingTimer;
void Start()
{
print("ProjectileWeapon start");
}
void OnGUI()
{
GUI.Label(new Rect(0,100,100,100), "ProjectileWeapon firing: " + firing);
}
void Update()
{
// this function is called but "firing" is not updated
}
public override void BeginCycle()
{
print("projectile begin cycle");
firing = true;
}
public override void EndCycle()
{
print("projectile end cycle");
firing = false;
}
}
Here's the base class:
public abstract class Weapon : MonoBehaviour
{
public abstract void BeginCycle();
public abstract void EndCycle();
}
EDIT: Here is the code that calls the above
This component is added to the player game object
public class WeaponHandler : MonoBehaviour
{
public bool FireInput { get; set; } // set to true when user holds the mouse button down, and false when let go
public Weapon WeaponBehaviour; // this is the script that does the weapon functionalility. Any subclass of Weapon can be put here e.g. ProjectileWeapon, MeleeWeapon
private bool isFiring = false;
void OnGUI()
{
GUI.Label(new Rect(0,0,100,100), "fire input:" + FireInput + ", isFiring:" + isFiring);
}
void Update()
{
// fire weapon
if (WeaponBehaviour && FireInput && !isFiring)
{
ActivateWeapon();
}
else if (!FireInput && isFiring)
{
DeActivateWeapon();
}
}
private void ActivateWeapon()
{
print("activate weapon");
isFiring = true;
WeaponBehaviour.BeginCycle();
}
private void DeActivateWeapon()
{
print("deactivate weapon");
isFiring = false;
WeaponBehaviour.EndCycle();
}
}

Based on the code you've provided, there are three possible scenarios:
You're not calling the functions. However, if the print functions are called, then you must be calling them.
You're calling both functions, which sets the variable to true, and then to false.
You're overriding the variable with a local variable with the same name. Visual Studio will warn you if that's the case.
It's hard to tell without knowing where the variables are supposed to be called. If you upload the rest of the code, I'm sure the answer will be clear.

It turns out it was how I was getting the ProjectileWeapon component. I was getting the one that was on the non-instantiated prefab instead of getting the one on weapon gameobject. I changed it so that the code instantiates the game object first (or gets the existing one if we've already picked it up), and then get the component from that. So the rest of the code works fine. Now I can move on and improve it!

Unity Error [error CS0120: An object reference is required for the non-static field, method, or property 'Zoney.setMonney(int)'] [duplicate]

This question already has answers here:
CS0120: An object reference is required for the nonstatic field, method, or property 'foo'
(9 answers)
Closed 2 years ago.
I keep getting this error, but I don't even know what is or isn't static in this context? I have tried solutions like setting instances and checking capitalization but I just get the same error. I want the shop script to change the monney value, which is written into debug until I set up the right U.I.
The Zoney script:
using UnityEngine;
using UnityEngine.UI;
public class Zoney : MonoBehaviour
{
public Text Money;
public int Monney;
private string Mony;
// Start is called before the first frame update
void Start()
{
Money = GetComponent<Text>();
}
public void setMonney(int Change)
{
Monney = Change;
}
// Update is called once per frame
void Update()
{
Mony = Monney.ToString();
Money.text = Mony;
}
}
The Shop script:
using UnityEngine;
public class Shop : MonoBehaviour
{
public int Change;
// Start is called before the first frame update
void Start()
{
}
// Update is called once per frame
void Update()
{
Change += 1;
Zoney.setMonney(Change);
Debug.Log(Change);
}
}

Because you're working with Unity, you need to follow the requirements of the engine.
In a case like this, where you need an instance of a component (MonoBehaviour), you really want to be referencing a Unity created instance, instead of creating a new one with the new keyword. Creating an instance of a component using the new keyword is going to leave you with an instance of the class that's not associated with any Unity GameObject.
The far more reliant way to get the component you want to reference, is to use the Inspector window, and drag into the object field, the right component on the desired object. In this case, I am going to assume you'll want to drag a Scene object (in your hierarchy) into the object field slot.
You would do that by first defining a variable. This can generally be done in one of two ways:
public Zoney zoney;
[SerializeField] private Zoney zoney;
In this example, once you've assigned your reference, use the variable zoney, instead of the class name Zoney. Note that your variable name could be anything else you feel is appropriate, e.g. _zoney, or myZoney.
Your new Shop script could then look like this:
public class Shop : MonoBehaviour
{
public int Change;
public Zoney zoney;
void Update()
{
Change += 1;
zoney.setMonney(Change);
Debug.Log(Change);
}
}

Zoney is a class, you need to create an instance of it first before using it.
Instantiate a class that derives from MonoBehaviour
Also very important, you need to update your shop object so it has the Zoney instance as a member object otherwise your updates to money wont be kept:
i.e.
public class Shop : MonoBehaviour
{
private Zoney;
public int Change;
// Start is called before the first frame update
void Start()
{
_HiddenZoney = gameObject.Addcomponent<Zoney>();
}
// Update is called once per frame
void Update()
{
Change += 1;
_HiddenZoney.setMoney(Change);
Debug.Log(Change);
}
}
Thanks #derHugo for the alert!

You need to create a object from Zoney class to access it's non static memebers. Try below:
public class Shop : MonoBehaviour
{
public int Change;
public Zoney myZoney; // Need to create the object
// Start is called before the first frame update
void Start()
{
}
// Update is called once per frame
void Update()
{
Change += 1;
myZoney.setMonney(Change); // Access members using created object
Debug.Log(Change);
}
}

How to set a GameObject active on one scene form a button click function on second scene that is loaded additive C#, Unity

I'm new to coding and Unity, I'm working on a simple click style game to learn the basics of both. I've created several scenes: MainMenu, UI, 1st level and 2nd level. After pressing 'Start' in main menu i'm loading UI and 1st level additively.
In UI layer I have a shop UI and other bits that I never want to unload. On the 1st and 2nd level i have the bits that i want to have only on those scenes.
So, what I'm trying to do is when i purchase an item or upgrade for the 1st level i want a GameObject (sprite) to be set as active.
What I've tried to do is to call a function in one script that is attached to GameObject in 1st level from script that is attached to a purchase button in UI scene, but from what I was able to understand from messing with it will set that game object active if it's assigned in the UI scene - so the whole thing is basicly pointless and i can do it much easier.
Code in script attached to GameObject in 1st level scene
public class Work_Button : MonoBehaviour
{
public GameObject hubert12;
public void Huberd()
{
hubert12.SetActive(true);
}
}
Code in script attached to GameObject in UI scene
public class Shop : MonoBehaviour
{
public GameObject buyHubertOnebutton;
public GameObject test;
public void UnlockHubert1()
{
if (Global_Cash.CashCount >= 20)
{
Global_Cash.CashCount -= 20;
buyHubertOnebutton.GetComponent<UnityEngine.UI.Button>().interactable = false;
Work_Button sn = test.GetComponent<Work_Button>();
sn.Huberd();
}
}
}
If you have any remarks anout how i've spit scenes or anything else they will be more than welcome!
Thanks!

There's something you need to be aware of, and that is that you can't reference an object from one scene, in another. You CAN reference the same Prefab though, but that's a slightly different issue.
One way I find effective is to do something like this:
public class Work_Button : MonoBehaviour
{
public GameObject hubert12;
public void Awake ( )
{
Shop.Register ( this );
}
public void Huberd ( )
{
hubert12.SetActive ( true );
}
}
Then you can have a Shop manager that has instance and static components.
public class Shop : MonoBehaviour
{
// Static variables
private static Work_Button _workButton;
// Instance variables
public GameObject buyHubertOnebutton;
public static void Register ( Work_Button workButton )
{
_workButton = workButton;
}
public void UnlockHubert1 ( )
{
if ( Global_Cash.CashCount >= 20 )
{
Global_Cash.CashCount -= 20;
buyHubertOnebutton.GetComponent<UnityEngine.UI.Button> ( ).interactable = false;
if ( _workButton != null )
_workButton.Huberd ( );
}
}
}
This works by having your button register with the shop. And because we're using the static variable here, we don't need to "find" the Shop object. The instance method UnlockHubert1 will check to make sure there is a button registered.
This represents just one of many ways to accomplish this. It's also the most basic of basic implementations. But as of right now I'm fond of this method. Extending this, you could store the registered items in a Dictionary collection, and you could do some cleanup/deregister when a button is destroyed (i.e. OnDestroy ).
The assumption here is that there is only one Work_Button in the scene, otherwise you'll need a way to differentiate them (i.e. a Dictionary with am identifier as the key).

Gameobject.find only returning null even when gameobject is active in heirarchy

I am trying to tranfer from one scene to another and trigger a function once this happens.
So when i press my play game button on my main menu page it loads a function to begin building the world. I have got the function to build a world but once ive attatched it to a button it has stopped working.
So far I believe this is down to me not fully understanding the method of calling a function from another class for it to run normally.
I begin to define my GameObject as:
private static GameOjbect Play;
This doesnt allow me to assign a GameObject to it within the unity editor. Therefore, i went down the method of using:
GameObject Play = GameObject.Find("PlayScreen");
My GameObeject is active in the heirarchy when this function begins but the program still does not function correctly. To test where the program is encountering an issue I used:
Debug.Log(Play);
Which i believed would just output "PlayScreen" to the debug log as this is the gameobject I am searching for, but this only returns "Null" and my program does not progress any further which is creating a wall.
Below is my main menu code:
public class MainMenu : MonoBehaviour
{
public GameObject PlayScene;
public GameObject SettingsScreen;
public void PlayGame()
{
SceneManager.LoadScene("InGame");
Debug.Log("Loading startup...");
WorldBuilder.Awake();
}
}
Below is my WorldBuilding function:
public class WorldBuilder:MonoBehaviour
{
public static GameObject Play;
public static void Awake()
{
Debug.Log("Finding Scene...");
GameObject Play = GameObject.Find("PlayScreen");
Debug.Log(Play);
}
}
How come my program is not finding the GameObject?
I am still new to C# so any sort of help is appreciated. Thankyou.

Don't make the Awake function static. If you do Unity won't call it.
Also, you are creating a local variable when you do GameObject Play = GameObject.Find("PlayScreen");. If you want to keep it in a static variable, you shouldn't do that. See below:
public class WorldBuilder : MonoBehaviour {
public static GameObject Play;
public static void Awake()
{
Debug.Log("Finding Scene...");
WorldBuilder.Play = GameObject.Find("PlayScreen");
Debug.Log(Play);
}
}
Also, remove the call in PlayGame:
public void PlayGame()
{
SceneManager.LoadScene("InGame");
Debug.Log("Loading startup...");
}

How to pass data (and references) between scenes in Unity

How can I pass score value from one scene to another?
I've tried the following:
Scene one:
void Start () {
score = 0;
updateScoreView ();
StartCoroutine (DelayLoadlevel(20));
}
public void updateScoreView(){
score_text.text = "The Score: "+ score;
}
public void AddNewScore(int NewscoreValue){
score = score + NewscoreValue;
updateScoreView ();
}
IEnumerator DelayLoadlevel(float seconds){
yield return new WaitForSeconds(10);
secondsLeft = seconds;
loadingStart = true;
do {
yield return new WaitForSeconds(1);
} while(--secondsLeft >0);
// here I should store my last score before move to level two
PlayerPrefs.SetInt ("player_score", score);
Application.LoadLevel (2);
}
Scene two:
public Text score_text;
private int old_score;
// Use this for initialization
void Start () {
old_score = PlayerPrefs.GetInt ("player_score");
score_text.text = "new score" + old_score.ToString ();
}
but nothing displayed on screen, and there's no error.
Is this the correct way to pass data ?
I am using Unity 5 free edition, develop game for Gear VR (meaning the game will run in android devices).
Any suggestion?

There are many ways to do this but the solution to this depends on the type of data you want to pass between scenes. Components/Scripts and GameObjects are destroyed when new scene is loaded and even when marked as static.
In this answer you can find
Use the static keyword
Use DontDestroyOnLoad
Store the data local
3a PlayerPrefs
3b serialize to XML/JSON/Binary and use FileIO
1. Use the static keyword.
Use this method if the variable to pass to the next scene is not a component, does not inherit from MonoBehaviour and is not a GameObject then make the variable to be static.
Built-in primitive data types such as int, bool, string, float, double. All those variables can be made a static variable.
Example of built-in primitive data types that can be marked as static:
static int counter = 0;
static bool enableAudio = 0;
static float timer = 100;
These should work without problems.
Example of Objects that can be marked as static:
public class MyTestScriptNoMonoBehaviour
{
}
then
static MyTestScriptNoMonoBehaviour testScriptNoMono;
void Start()
{
testScriptNoMono = new MyTestScriptNoMonoBehaviour();
}
Notice that the class does not inherit from MonoBehaviour. This should work.
Example of Objects that cannot be marked as static:
Anything that inherits from Object, Component or GameObject will not work.
1A.Anything that inherits from MonoBehaviour
public class MyTestScript : MonoBehaviour
{
}
then
static MyTestScript testScript;
void Start()
{
testScript = gameObject.AddComponent<MyTestScript>();
}
This will not work because it inherits from MonoBehaviour.
1B.All GameObject:
static GameObject obj;
void Start()
{
obj = new GameObject("My Object");
}
This will not work either because it is a GameObject and GameObject inherit from an Object.
Unity will always destroy its Object even if they are declared with the static keyword.
See #2 for a workaround.
2.Use the DontDestroyOnLoad function.
You only need to use this if the data to keep or pass to the next scene inherits from Object, Component or is a GameObject. This solves the problem described in 1A and 1B.
You can use it to make this GameObject not to destroy when scene unloads:
void Awake()
{
DontDestroyOnLoad(transform.gameObject);
}
You can even use it with the static keyword solve problem from 1A and 1B:
public class MyTestScript : MonoBehaviour
{
}
then
static MyTestScript testScript;
void Awake()
{
DontDestroyOnLoad(transform.gameObject);
}
void Start()
{
testScript = gameObject.AddComponent<MyTestScript>();
}
The testScript variable will now be preserved when new scene loads.
3.Save to local storage then load during next scene.
This method should be used when this is a game data that must be preserved when the game is closed and reopened. Example of this is the player high-score, the game settings such as music volume, objects locations, joystick profile data and so on.
Thare are two ways to save this:
3A.Use the PlayerPrefs API.
Use if you have just few variables to save. Let's say player score:
int playerScore = 80;
And we want to save playerScore:
Save the score in the OnDisable function
void OnDisable()
{
PlayerPrefs.SetInt("score", playerScore);
}
Load it in the OnEnable function
void OnEnable()
{
playerScore = PlayerPrefs.GetInt("score");
}
3B.Serialize the data to json, xml or binaray form then save using one of the C# file API such as File.WriteAllBytes and File.ReadAllBytes to save and load files.
Use this method if there are many variables to save.
General, you need to create a class that does not inherit from MonoBehaviour. This class you should use to hold your game data so that in can be easily serialized or de-serialized.
Example of data to save:
[Serializable]
public class PlayerInfo
{
public List<int> ID = new List<int>();
public List<int> Amounts = new List<int>();
public int life = 0;
public float highScore = 0;
}
Grab the DataSaver class which is a wrapper over File.WriteAllBytes and File.ReadAllBytes that makes saving data easier from this post.
Create new instance:
PlayerInfo saveData = new PlayerInfo();
saveData.life = 99;
saveData.highScore = 40;
Save data from PlayerInfo to a file named "players":
DataSaver.saveData(saveData, "players");
Load data from a file named "players":
PlayerInfo loadedData = DataSaver.loadData<PlayerInfo>("players");

There is another way:
ScriptableObject
ScriptableObjects are basically data containers but may also implement own logic. They "live" only in the Assets like prefabs. They can not be used to store data permanently, but they store the data during one session so they can be used to share data and references between Scenes ... and - something I also often needed - between Scenes and an AnimatorController!
Script
First you need a script similar to MonoBehaviours. A simple example of a ScriptableObject might look like
// fileName is the default name when creating a new Instance
// menuName is where to find it in the context menu of Create
[CreateAssetMenu(fileName = "Data", menuName = "Examples/ExamoleScriptableObject")]
public class ExampleScriptableObject : ScriptableObject
{
public string someStringValue = "";
public CustomDataClass someCustomData = null;
public Transform someTransformReference = null;
// Could also implement some methods to set/read data,
// do stuff with the data like parsing between types, fileIO etc
// Especially ScriptableObjects also implement OnEnable and Awake
// so you could still fill them with permanent data via FileIO at the beginning of your app and store the data via FileIO in OnDestroy !!
}
// If you want the data to be stored permanently in the editor
// and e.g. set it via the Inspector
// your types need to be Serializable!
//
// I intentionally used a non-serializable class here to show that also
// non Serializable types can be passed between scenes
public class CustomDataClass
{
public int example;
public Vector3 custom;
public Dictionary<int, byte[]> data;
}
Create Instances
You can create instances of ScriptableObject either via script
var scriptableObject = ScriptableObject.CreateInstance<ExampleScriptableObject>();
or to make things easier use the [CreateAssetMenu] as shown in the example above.
As this created ScriptabeObject instance lives in the Assets it is not bound to a scene and can therefore be referenced everywhere!
This when you want to share the data between two Scenes or also e.g. the Scene and an AnimatorController all you need to do is reference this ScriptableObject instance in both.
Fill Data
I often use e.g. one component to fill the data like
public class ExampleWriter : MonoBehaviour
{
// Here you drag in the ScriptableObject instance via the Inspector in Unity
[SerializeField] private ExampleScriptableObject example;
public void StoreData(string someString, int someInt, Vector3 someVector, List<byte[]> someDatas)
{
example.someStringValue = someString;
example.someCustomData = new CustomDataClass
{
example = someInt;
custom = someVector;
data = new Dictionary<int, byte[]>();
};
for(var i = 0; i < someDatas.Count; i++)
{
example.someCustomData.data.Add(i, someDatas[i]);
}
example.someTransformReference = transform;
}
}
Consume Data
So after you have written and stored your required data into this ExampleScriptableObject instance every other class in any Scene or AnimatorController or also other ScriptableObjects can read this data on just the same way:
public class ExmpleConsumer : MonoBehaviour
{
// Here you drag in the same ScriptableObject instance via the Inspector in Unity
[SerializeField] private ExampleScriptableObject example;
public void ExampleLog()
{
Debug.Log($"string: {example.someString}", this);
Debug.Log($"int: {example.someCustomData.example}", this);
Debug.Log($"vector: {example.someCustomData.custom}", this);
Debug.Log($"data: There are {example.someCustomData.data.Count} entries in data.", this);
Debug.Log($"The data writer {example.someTransformReference.name} is at position {example.someTransformReference.position}", this);
}
}
Persistence
As said the changes in a ScriptableObject itself are only in the Unity Editor really persistent.
In a build they are only persistent during the same session.
Therefore if needed I often combine the session persistence with some FileIO (as described in this answer's section 3b) for loading and deserializing the values once at session begin (or whenever needed) from the hard drive and serialize and store them to a file once on session end (OnApplicationQuit) or whenever needed.
(This won't work with references of course.)

Besides playerPrefs another dirty way is to preserve an object during level loading by calling DontDestroyOnLoad on it.
DontDestroyOnLoad (transform.gameObject);
Any script attached to the game object will survive and so will the variables in the script.
The DontDestroyOnLoad function is generally used to preserve an entire GameObject, including the components attached to it, and any child objects it has in the hierarchy.
You could create an empty GameObject, and place only the script containing the variables you want preserved on it.

I use a functional approach I call Stateless Scenes.
using UnityEngine;
public class MySceneBehaviour: MonoBehaviour {
private static MySceneParams loadSceneRegister = null;
public MySceneParams sceneParams;
public static void loadMyScene(MySceneParams sceneParams, System.Action<MySceneOutcome> callback) {
MySceneBehaviour.loadSceneRegister = sceneParams;
sceneParams.callback = callback;
UnityEngine.SceneManagement.SceneManager.LoadScene("MyScene");
}
public void Awake() {
if (loadSceneRegister != null) sceneParams = loadSceneRegister;
loadSceneRegister = null; // the register has served its purpose, clear the state
}
public void endScene (MySceneOutcome outcome) {
if (sceneParams.callback != null) sceneParams.callback(outcome);
sceneParams.callback = null; // Protect against double calling;
}
}
[System.Serializable]
public class MySceneParams {
public System.Action<MySceneOutcome> callback;
// + inputs of the scene
}
public class MySceneOutcome {
// + outputs of the scene
}
You can keep global state in the caller's scope, so scene inputs and outputs states can be minimized (makes testing easy). To use it you can use anonymous functions:-
MyBigGameServices services ...
MyBigGameState bigState ...
Splash.loadScene(bigState.player.name, () => {
FirstLevel.loadScene(bigState.player, (firstLevelResult) => {
// do something else
services.savePlayer(firstLevelResult);
})
)}
More info at https://corepox.net/devlog/unity-pattern:-stateless-scenes

There are various way, but assuming that you have to pass just some basic data, you can create a singelton instance of a GameController and use that class to store the data.
and, of course DontDestroyOnLoad is mandatory!
public class GameControl : MonoBehaviour
{
//Static reference
public static GameControl control;
//Data to persist
public float health;
public float experience;
void Awake()
{
//Let the gameobject persist over the scenes
DontDestroyOnLoad(gameObject);
//Check if the control instance is null
if (control == null)
{
//This instance becomes the single instance available
control = this;
}
//Otherwise check if the control instance is not this one
else if (control != this)
{
//In case there is a different instance destroy this one.
Destroy(gameObject);
}
}
Here is the full tutorial with some other example.

you have several options.
The first one I see is to use static variables, which you will not lose their information or value passing from scenes to scenes (since they are not bound to the object). [you lose the information when closing the game, but not when passing between scenes]
the second option is that the player or the object of which you do not want to lose the information, you pass it through the DontDestroyOnLoad function
Here I give you the documentation and the sample code. [You lose the information when you close the game, but not when you go between scenes]
https://docs.unity3d.com/ScriptReference/Object.DontDestroyOnLoad.html
Third is to use the playerPrefab [https://docs.unity3d.com/ScriptReference/PlayerPrefs.html]
that allow you to save information and retrieve it at any time without hanging it even after closing the game [you must be very careful with the latter if you plan to use it to save data even after closing the game since you can lose the data if you close the game suddenly , since player prefab creates a file and retrieves the information from there, but it saves the file at the end or closes the app correctly]