I am making a script for a unity project to destroy an instantiated clone if it collides with another clone, but since the Game Object (the clone) is declared in the start method and I cannot put it at the top I need to figure out how to destroy the clone if it collides with something else.
This is the error I get if I put it on top:
A field initializer cannot reference the non-static field, method, or property
Code:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class topbigspike : MonoBehaviour
{
public GameObject Flame;
// Start is called before the first frame update
void Start()
{
int a = 30;
int i = 0;
while (0 < a)
{
a--;
i++;
GameObject FlameClone = Instantiate(Flame);
FlameClone.transform.position = new Vector3(Random.Range(10, 2000), -3, 0);
}
}
void OnCollisionEnter2D(Collision2D col)
{
Destroy(FlameClone);
}
}
As the error message says, you cannot use Flame as field initializer. But you can still declare FlameClone as field (at the top, as you say) ) and initialize it in the Start method:
public class topbigspike : MonoBehaviour
{
public GameObject Flame;
public GameObject FlameClone; // <=== Declare here, as class field.
// Start is called before the first frame update
void Start()
{
int a = 30;
int i = 0;
while (0 < a)
{
a--;
i++;
FlameClone = Instantiate(Flame); // <=== Initialize here.
FlameClone.transform.position = new Vector3(Random.Range(10, 2000), -3, 0);
}
}
void OnCollisionEnter2D(Collision2D col)
{
Destroy(FlameClone);
}
}
As already mentioned you need to store it a field in order to access it from other methods.
However, seeing a while loop there instantiating multiple (30) instances a single field isn't enough anyway except you really want to only destroy the last created instance.
It should probably rather be e.g.
public class topbigspike : MonoBehaviour
{
public int amount = 30;
public GameObject Flame;
private GameObject[] flameInstances;
void Start()
{
flameInstances = new GameObject[amount];
for(var i = 0; i < amount; i++)
{
var flameInstance = Instantiate(Flame);
flameInsance.transform.position = new Vector3(Random.Range(10, 2000), -3, 0);
flameInstances[i] = flameInstance;
}
}
void OnCollisionEnter2D(Collision2D col)
{
foreach(var flameInstance in flameInstances)
{
Destroy(flameInstance);
}
}
}
Related
I am practicing with C # Lists in Unity and I have encountered a problem.
My test script, instantiates 5 prefabs which are added in a gameobject list. I then wrote a code that generates a random int and from that number moves the prefab instantiated with that index (indexof). Everything works correctly, but the method that moves and deletes the prefab is repeated for all the gameobjects in the scene with an index higher than the one chosen. I enclose the two scripts to better explain the problem. (I would need the unlist method to be done only once.
how can i solve this problem and remove one item from the list at a time? (one each time the button is pressed, not all as it is now. Thanks)
script:
NpcController: Added in each instantiated prefab
ListCOntroller: added in the scene.
public class ListCOntroller : MonoBehaviour
{
public GameObject cubePrefab;
private GameObject cubeInstance;
public static List<GameObject> cubeList = new List<GameObject> ();
public TextMeshProUGUI checkText;
public static event Action chooseNpc;
public static int randNpcValue;
int rand;
private void Start()
{
for(int i =0; i < 5; i++)
{
cubeInstance = Instantiate(cubePrefab, new Vector3(i, -2, 0), Quaternion.identity);
cubeList.Add(cubeInstance);
}
}
public void CheckListText()
{
checkText.text = "Npc in list: " + cubeList.Count.ToString();
}
public static void SelectRandomCube()
{
randNpcValue = Random.Range(0, cubeList.Count);
chooseNpc?.Invoke();
}
}
public class NpcController : MonoBehaviour
{
void Start()
{
ListCOntroller.chooseNpc += NpcEvent;
}
private void NpcEvent()
{
if (ListCOntroller.cubeList.IndexOf(gameObject) == ListCOntroller.randNpcValue)
{
transform.localPosition = new Vector3(transform.position.x, 2, 0);
DeleteFromList();
}
}
private void DeleteFromList()
{
ListCOntroller.cubeList.RemoveAt(ListCOntroller.randNpcValue);
Debug.Log($"Delete from list: {ListCOntroller.randNpcValue}");
}
}
the int random number generated in the attached images is: 2
Because events are executed one after another.
Let's say you have 3 NPCs: NPC0, NPC1, NPC2
Now the random number you choosen is 1, when NPC1's NpcEvent runs, ListCOntroller.cubeList.IndexOf(gameObject) is 1 which equals to the randNpcValue, and then NPC1 will be removed from the list.
Note that now the list has 2 items left: NPC0, NPC2. Next NPC2's NpcEvent runs in turn, at this time, ListCOntroller.cubeList.IndexOf(gameObject) is still 1 because the list has only 2 items, so NPC2 is also removed from the list.
A solution is you can change the randNpcValue to an invalid value when a NPC is removed.
if (ListCOntroller.cubeList.IndexOf(gameObject) == ListCOntroller.randNpcValue)
{
transform.localPosition = new Vector3(transform.position.x, 2, 0);
DeleteFromList();
ListCOntroller.randNpcValue = -2;
}
In addition to this answer in general I don't really see the purpose mixing the the logic into two different scripts.
You have one for storing a list and raising an event and the other one listens to the event and manipulates the stored list -> This doesn't sounds right.
You could as well simply do `why don't you pass a long the the according object into the event in the first place and rather do something like
public class ListCOntroller : MonoBehaviour
{
// Singleton instance
private static ListCOntroller _instance;
// Read-only getter
public static ListCOntroller Instance => _instance;
// pass in the target object reference instead of doing things index based
public event Action<GameObject> chooseNpc;
public GameObject cubePrefab;
// THIS is the list controller -> nobody else should be able to manipulate this list
private readonly List<GameObject> cubeList = new ();
public TextMeshProUGUI checkText;
private void Awake()
{
if(_instance && _instance != this)
{
Destroy(this);
return;
}
_instance = this;
}
private void Start()
{
for(int i =0; i < 5; i++)
{
cubeInstance = Instantiate(cubePrefab, new Vector3(i, -2, 0), Quaternion.identity);
cubeList.Add(cubeInstance);
}
}
public static void SelectRandomCube()
{
if(cubeList.Count == 0)
{
Debug.LogWarning("Trying to pick item from empty list");
return;
}
var randomIndex = Random.Range(0, cubeList.Count);
var randomItem = cubeList[randomIndex];
// remove from the list yourself instead of relying on others to work correctly
cubeList.RemoveAt(randomIndex);
// pass along the target object
chooseNpc?.Invoke(randomItem);
}
}
and then
public class NpcController : MonoBehaviour
{
void Start()
{
ListCOntroller.Instance.chooseNpc += NpcEvent;
}
private void NpcEvent(GameObject target)
{
// check if you are the target object
if (target == gameObject))
{
// adjust your position - you don't care about other NPCs or the existence of a list
transform.localPosition = new Vector3(transform.position.x, 2, 0);
}
}
}
I am at begginner level with unity.
I have Load() function that goes off in OnApplicationPause(false). It works fine if I block the screen or minimalise app, and come back to it. However, when I kill it, I get error and the data doesnt get loaded.
Below is the script attached to the GameObject "SaveManager"
using System.Collections.Generic;
using UnityEngine;
using System;
public class SaveManager : MonoBehaviour
{
public GameObject ZwierzetaGroup;
public GameObject JedzeniaGroup;
public GameObject PrzedmiotyGroup;
public List<GameObject> zwierzeta_sprites;
public List<GameObject> jedzenia_sprites;
public List<GameObject> przedmioty_sprites;
public static DateTime oldDate;
Camera mainCamera;
public SaveState saveState;
void Start()
{
mainCamera = Camera.main;
FillArrays();
}
public void Save()
{
Debug.Log("Saving.");
SaveSpriteArray("zwierze", zwierzeta_sprites);
SaveSpriteArray("przedmiot", przedmioty_sprites);
SaveSpriteArray("jedzenie", jedzenia_sprites);
PlayerPrefs.SetInt("pieniazki", saveState.GetPieniazki());
PlayerPrefs.SetInt("HayAmount", saveState.GetHayAmount());
PlayerPrefs.SetInt("HayMax", saveState.GetHayMax());
PlayerPrefs.SetInt("FruitAmount", saveState.GetFruitAmount());
PlayerPrefs.SetInt("FruitMax", saveState.GetFruitMax());
//time:
PlayerPrefs.SetString("sysString", System.DateTime.Now.ToBinary().ToString());
PlayerPrefs.SetInt("First", 1);
}
public void SaveSpriteArray(string saveName, List<GameObject> sprites)
{
for (int i = 0; i < sprites.Count; i++)
{
if (sprites[i].activeSelf)
{
PlayerPrefs.SetInt(saveName + i, 1);
}
else
{
PlayerPrefs.SetInt(saveName + i, 0);
}
}
}
public void Load()
{
Debug.Log("Loading.");
//wczytanie czasu:
long temp = Convert.ToInt64(PlayerPrefs.GetString("sysString"));
oldDate = DateTime.FromBinary(temp);
Debug.Log("oldDate: " + oldDate);
//wczytywanie aktywnych sprite'ow
LoadSpriteArray("zwierze", zwierzeta_sprites);
LoadSpriteArray("przedmiot", przedmioty_sprites);
LoadSpriteArray("jedzenie", jedzenia_sprites);
saveState.SetPieniazki(PlayerPrefs.GetInt("pieniazki"));
saveState.SetHayAmount(PlayerPrefs.GetInt("HayAmount"));
saveState.SetHayMax(PlayerPrefs.GetInt("HayMax"));
saveState.SetFruitAmount(PlayerPrefs.GetInt("FruitAmount"));
saveState.SetFruitMax(PlayerPrefs.GetInt("FruitMax"));
mainCamera.GetComponent<UpdateMoney>().MoneyUpdate();
}
public void LoadSpriteArray(string saveName, List<GameObject> sprites)
{
for (int i = 0; i < sprites.Count; i++)
{
if (PlayerPrefs.GetInt(saveName + i) == 1)
{
sprites[i].SetActive(true);
}
else
{
sprites[i].SetActive(false);
}
}
}
private void FillArrays()
{
//find children
foreach (Transform child in ZwierzetaGroup.transform)
{
zwierzeta_sprites.Add(child.gameObject);
}
foreach (Transform child in PrzedmiotyGroup.transform)
{
przedmioty_sprites.Add(child.gameObject);
}
foreach (Transform child in JedzeniaGroup.transform)
{
jedzenia_sprites.Add(child.gameObject);
}
}
}
Below is a chunk of script attached to the main camera (probably a mistake). SaveManager GameObject with Script is attached to this one in inspector. This script is pretty big, so I'll skip the parts that I don't find relevant.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System;
public class ManageEncouters: MonoBehaviour
{
DateTime currentDate;
public int First;
public SaveState saveState;
public SaveManager saveManager;
public HayBar hayBar;
public FruitBar fruitBar;
public GameObject[] jedzenia_sprites;
void Start()
{
}
void OnApplicationPause(bool pauseStatus)
{
if (!pauseStatus)
{
currentDate = System.DateTime.Now;
//Sprawdzanie czy jest to piersze uruchomienie gry (brak zapisu)
First = PlayerPrefs.GetInt("First");
if (First == 0)
{
Debug.Log("First time in app.");
RandomiseAnimals();
SaveManager.oldDate = currentDate;
hayBar.SetHayMax(1);
hayBar.SetHay(0);
fruitBar.SetFruitMax(1);
fruitBar.SetFruit(0);
saveState.SetPieniazki(100);
this.GetComponent<UpdateMoney>().MoneyUpdate();
}
else
{
Debug.Log("Not the first time in app.");
saveManager.Load();
}
if (TimeInSeconds(currentDate, SaveManager.oldDate) > 12)
{
Debug.Log("It's been more than 12 seconds sience last time.");
EatFood(currentDate, SaveManager.oldDate);
RandomiseAnimals();
}
else
{
Debug.Log("It's been less than 12 seconds sience last time.");
}
}
if (pauseStatus)
{
saveManager.Save();
}
}
private int TimeInSeconds(DateTime newD, DateTime oldD)
{
TimeSpan difference = newD.Subtract(oldD);
int seconds = (int)difference.TotalSeconds;
return seconds;
}
}
Below is the error I get, I don't know how to copy the text, so it's an Image.
I'm pretty sure that what you have here is a timing issue.
OnApplicationPause
Note: MonoBehaviour.OnApplicationPause is called as a GameObject starts. The call is made after Awake. Each GameObject will cause this call to be made.
So to me this sounds like it might be called when your SaveManager is not yet initialized, in particular the mainCamera.
I think you could already solve the issue by moving the initialization into Awake instead
private void Awake()
{
mainCamera = Camera.main;
FillArrays();
}
In general my little thumb rule is
use Awake wherever possible. In particular initialize everything where you don't depend on other scripts (initialize fields, use GetComponent, etc)
use Start when you need other scripts to be initialized already (call methods on other components, collect and pass on instances of some prefabs spawned in Awake, etc)
This covers most of cases. Where this isn't enough you would need to bother with the execution order or use events.
I have two scripts each one attached to another empty GameObject:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class ObjectPooler : MonoBehaviour
{
[System.Serializable]
public class Pool
{
public string tag;
public GameObject prefab;
public int size;
}
#region Singleton
public static ObjectPooler Instance;
private void Awake()
{
Instance = this;
}
#endregion
public List<Pool> pools;
public Dictionary<string, Queue<GameObject>> poolDictionary;
// Start is called before the first frame update
void Start()
{
poolDictionary = new Dictionary<string, Queue<GameObject>>();
foreach(Pool pool in pools)
{
Queue<GameObject> objectPool = new Queue<GameObject>();
for(int i = 0; i < pool.size; i++)
{
GameObject obj = Instantiate(pool.prefab);
obj.SetActive(false);
objectPool.Enqueue(obj);
}
poolDictionary.Add(pool.tag, objectPool);
}
}
public GameObject SpawnFromPool(string tag, Vector3 position, Quaternion rotation)
{
if(!poolDictionary.ContainsKey(tag))
{
Debug.LogWarning("Pool with tag " + tag + " doesn't exist.");
return null;
}
GameObject objectToSpawn = poolDictionary[tag].Dequeue();
objectToSpawn.SetActive(true);
objectToSpawn.transform.position = position;
objectToSpawn.transform.rotation = rotation;
IPooledObject pooledObj = objectToSpawn.GetComponent<IPooledObject>();
if(pooledObj != null)
{
pooledObj.OnObjectSpawn();
}
poolDictionary[tag].Enqueue(objectToSpawn);
return objectToSpawn;
}
}
And the second one and here I added inside the FixedUpdate the random part:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class CubeSpawner : MonoBehaviour
{
ObjectPooler objectPooler;
// Start is called before the first frame update
void Start()
{
objectPooler = ObjectPooler.Instance;
}
private void FixedUpdate()
{
var randp = new Vector3(Random.Range(0, 300), Random.Range(0, 300), Random.Range(0, 300));
objectPooler.SpawnFromPool("Cube", randp, Quaternion.identity);
}
}
It does what I want so far, But did I add the random part in the right script and place?
And how can I make that instead of generating nonstop random objects it will generate them only when I will change a Range slider of the size variable?
For example [Range(1,150])
And when I change the value it will add/remove the objects in the FixedUpdate? (It should be Update it's FixedUpdate since before that I used a Rigidbody but not now).
The idea is to either to change the size or if I set the size for example to 1000 and then to use a Range slider to change the number of using objects for example 445 or 500 or 1000.
And each time I change the size it will random the objects in other random positions. But once and not all the time like now in the FixedUpdate.
Each time changing the size change the objects positions randomly.
So if the size I changed it to 10 change the position of 10 objects randomly and use only these 10 objects. If I change the size to 700 then reposition randomly 700 objects and use the 700. (Not sure if it's right to say use or destroy).
UPDATE:
This is what I tried in the the first script I added the oldSize variable and the Range:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class ObjectPooler : MonoBehaviour
{
[System.Serializable]
public class Pool
{
public string tag;
public GameObject prefab;
[Range(1, 150)]
public int size;
public int sizeOld;
}
#region Singleton
public static ObjectPooler Instance;
private void Awake()
{
Instance = this;
}
#endregion
public List<Pool> pools;
public Dictionary<string, Queue<GameObject>> poolDictionary;
// Start is called before the first frame update
void Start()
{
poolDictionary = new Dictionary<string, Queue<GameObject>>();
foreach(Pool pool in pools)
{
Queue<GameObject> objectPool = new Queue<GameObject>();
for(int i = 0; i < pool.size; i++)
{
GameObject obj = Instantiate(pool.prefab);
obj.SetActive(false);
objectPool.Enqueue(obj);
}
poolDictionary.Add(pool.tag, objectPool);
}
}
private void Update()
{
}
public GameObject SpawnFromPool(string tag, Vector3 position, Quaternion rotation)
{
if(!poolDictionary.ContainsKey(tag))
{
Debug.LogWarning("Pool with tag " + tag + " doesn't exist.");
return null;
}
GameObject objectToSpawn = poolDictionary[tag].Dequeue();
objectToSpawn.SetActive(true);
objectToSpawn.transform.position = position;
objectToSpawn.transform.rotation = rotation;
IPooledObject pooledObj = objectToSpawn.GetComponent<IPooledObject>();
if(pooledObj != null)
{
pooledObj.OnObjectSpawn();
}
poolDictionary[tag].Enqueue(objectToSpawn);
return objectToSpawn;
}
}
And in the second script in the Start I'm using once the whole objects for example I start the game when the Range value is at 27 and then when changing the value I'm updating the oldSize:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class CubeSpawner : MonoBehaviour
{
ObjectPooler objectPooler;
// Start is called before the first frame update
void Start()
{
objectPooler = ObjectPooler.Instance;
foreach (ObjectPooler.Pool pool in objectPooler.pools)
{
var randp = new Vector3(Random.Range(0, 300), Random.Range(0, 300), Random.Range(0, 300));
objectPooler.SpawnFromPool("Cube", /*transform.position*/ randp, Quaternion.identity);
}
}
private void Update()
{
foreach (ObjectPooler.Pool pool in objectPooler.pools)
{
if (pool.size != pool.sizeOld)
{
int diff = pool.size - pool.sizeOld;
pool.sizeOld = pool.size;
// Spawn new diff number of objects if diff is positive
var randp = new Vector3(Random.Range(0, 300), Random.Range(0, 300), Random.Range(0, 300));
objectPooler.SpawnFromPool("Cube", /*transform.position*/ randp, Quaternion.identity);
}
}
//var randp = new Vector3(Random.Range(0, 300), Random.Range(0, 300), Random.Range(0, 300));
//objectPooler.SpawnFromPool("Cube", transform.position /*randp*/, Quaternion.identity);
}
}
But in fact the spawners in the Hierarhcy never changed there is all the time 27. If the Range is lower then 27 it will use less objects but if it's higher then 27 still in the hierarchy there will be only 27 spawners.
The size of spawners never change. And then when moving the Range left right it will fill the spawners use them until the end and that's it it will never change it will use them all but only 27.
Even if Range value is 150 for example still there are 27 spawners in the hierarhcy and in the game it self and not 150.
It does what I want so far, But did I add the random part in the right script and place ?
I don't know, if you ask me is 1 + 1 = 2, I can give you an answer.
And how can I make that instead generating nonstop random objects it will generate them only when I will change a Range slider of the size variable ?
You need another size field:
public class Pool
{
public string tag;
public GameObject prefab;
[Range(1, 150)]
public int size;
private int sizeOld;
}
Then in the Update of FixedUpdate do a simple compare:
void Update()
{
foreach(Pool pool in pools)
{
if(pool.size != pool.sizeOld)
{
int diff = pool.size - pool.sizeOld;
pool.sizeOld = pool.size;
// Spawn new diff number of objects if diff is positive
}
}
}
And when I change the value it will add/remove the objects in the FixedUpdate ?
Depends on where you call spawning method.
I have been doing a RPG game in Unity with C # and when doing a system of quests, specifically those of killing a certain number of enemies, I found the problem of having 3 enemies in the scene and being the target of the quest: Kill 3 enemies. If I kill them before activating the quest and later active the quest does not give me the reward (in this case experience). How can I tell the enemies and make that if the quest detects that I have already killed the necessary enemies to get the quest give me the reward equally?
Here the two needed scripts i think:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class QuestObject : MonoBehaviour {
public int questNumber;
public QuestManager qManager;
public string startText;
public string endText;
public bool isItemQuest;
public string targetItem;
public bool isEnemyQuest;
public string targetEnemy;
public int enemiesToKill;
private int enemyKillCount;
private PlayerStats playerStats;
public int EXPToGive;
void Start () {
playerStats = FindObjectOfType <PlayerStats> ();
}
void Update () {
if (isItemQuest) {
if (qManager.itemCollected == targetItem) {
qManager.itemCollected = null;
EndQuest ();
}
}
if (isEnemyQuest) {
if (qManager.enemyKilled == targetEnemy) {
qManager.enemyKilled = null;
enemyKillCount++;
}
if (enemyKillCount >= enemiesToKill) {
EndQuest ();
}
}
}
public void StartQuest (){
qManager.ShowQuestText (startText);
}
public void EndQuest (){
qManager.ShowQuestText (endText);
playerStats.AddEXP (EXPToGive);
qManager.questCompleted [questNumber] = true;
gameObject.SetActive (false);
}
}
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class EnemyHealth : MonoBehaviour {
public int startingHealth;
public int currentHealth;
public GameObject damageBurst;
private PlayerStats playerStats;
public int EXPToGive;
public string enemyQuestName;
private QuestManager qManager;
void Start ()
{
// Setting up the references.
//anim = GetComponent <Animator> ();
//enemyAudio = GetComponent <AudioSource> ();
//enemyMovement = GetComponent <EnemyMovement> ();
//enemyAttacking = GetComponentInChildren <EnemyAttack> ();
// Set the initial health of the player.
currentHealth = startingHealth;
playerStats = FindObjectOfType <PlayerStats> ();
qManager = FindObjectOfType <QuestManager> ();
}
void Update ()
{
if (currentHealth <= 0) {
qManager.enemyKilled = enemyQuestName;
Destroy (gameObject);
playerStats.AddEXP (EXPToGive);
}
}
public void TakeDamage (int amountDamage)
{
// Reduce the current health by the damage amount.
currentHealth -= amountDamage;
Instantiate (damageBurst, transform.position, transform.rotation);
}
public void SetMaxHelth () {
currentHealth = startingHealth;
}
}
One Aproach would be to create some type of "WorldManager" which counts every Enemy which has been slain. And when Starting a quest this quest could check the WorldManagers kill count and add it to it's own count.
public void StartQuest (){
qManager.ShowQuestText (startText);
this.enemyKillCount += worldManager.GetKillCount();
}
In your enemy class you have to add a kill to your worldManager.
void Update ()
{
if (currentHealth <= 0) {
qManager.enemyKilled = enemyQuestName;
this.worldManager.AddKill(this)
Destroy (gameObject);
playerStats.AddEXP (EXPToGive);
}
}
Alternative:
Make your QManager be aware of every kill in a Scene.
You can achieve this through many ways.
One of them is passing your EnemyObject an reference of your Qmanager and do the same as with the "WorldManager" provided above, or you use Messaging and fire a Message targeting the QManager when an enemy is slain.
Alternative 2:
Throw an Event when an enemy has been slain and subscribe to it on your QManager/WorldManager. This way u can reuse your enemy class in every game. From my point of view static dependencies are evil, but there are many discussions and SO and everywhere on the internet about that.
You can several approach. The most straight-forward is to use static.
The purpose of static is for the variable/method to belong to the class instead of an instance of the class.
In your case, you want each enemy to have its own health, this cannot be static.
And you want to count how many instances there are in the scene from the class. So static is fine.
public class Enemy:MonoBehaviour
{
private static int enemyCount = 0;
public static int EnemyCount {get{ return enemyCount;} }
public event Action<int> RaiseEnemyDeath;
public static void ResetEnemyCount(){
enemyCount = 0;
}
private int health;
public void Damage(int damage)
{
CheckForDamage(); // here you check that damage is not neg or too big...
this.health -= damage;
if(this.health <= 0)
{
OnDeath();
}
}
void OnActivate()
{
enemyCount++;
this.health = 20;
}
void OnDeath()
{
enemyCount--;
RaiseEnemyDeath(enemyCount); // Should check for nullity...
}
}
This one is fairly simple. The first part is all static and is relevant to the class. The second part is relevant to the instance. If you use a pool of enemy and then reuse the same instance multiple times, the OnActivate method is called when you make the enemy alive in the scene (it may have been there for a while as inactive). Then when the health is down, kill the enemy (there are not all the required actions there...) and trigger the event.
Using the public static property, you can know what is the enemy count from a GameManager (Enemy should not affect the gameplay, only takes care of the enemy).
public class GameManager:MonoBehaviour
{
void Start()
{
Enemy.RaiseEnemyDeath += Enemy_RaiseEnemyDeath;
}
void Enemy_RaiseEnemyDeath(int count)
{
if(count < 0){ // End of level }
// You can also access enemyCount
int count = Enemy.EnemyCount;
}
}
The good point of using this principle is that Enemy has no clue about GameManager and can be reused in another game without any modification. The GameManager is a higher level entity and knows about it.
Okay so before I begin, Yes I have looked online to find this answer. I've followed advice on multiple other questions, gone through the unity documentation, and done more than a few web searches and nothing I've found so far has solved the error. I'm sure someone will take one look at this and know immediately what's wrong, but as for me, I just can't find it.
Now that that's out of the way Here's the problem. I'm making a Breakout clone and I had everything done, everything working properly. I've got one static class that takes care of the scoring and score related variables, so that other scripts can access them easily. I wanted to practice some basic saving and loading with PlayerPrefs, so I added something for highscores. It's pretty much independent of the other classes, but once I finished that, I started getting a Null Reference Exception in a script that has been done for hours, and was working fine.
I appreciate any help you might have, and any tips for preventing this kind of error the next time around. Sorry It's such a long question.
Here's the full error:
NullReferenceException: Object reference not set to an instance of an object
MenuManager.ActivateLose () (at Assets/Scripts/MenuScripts/MenuManager.cs:31)
Scoring.CheckGameOver () (at Assets/Scripts/Scoring.cs:64)
Scoring.LifeLost () (at Assets/Scripts/Scoring.cs:51)
DeadZone.OnTriggerEnter2D (UnityEngine.Collider2D other) (at Assets/Scripts/DeadZone.cs:22)
And here are the three scripts listed in said error:
using UnityEngine;
using System.Collections;
public class DeadZone : MonoBehaviour
{
public GameObject ballPrefab;
public Transform paddleObj;
GameObject ball;
void Update ()
{
ball = GameObject.FindGameObjectWithTag("Ball");
}
void OnTriggerEnter2D(Collider2D other)
{
//if the object that entered the trigger is the ball
if(other.tag == "Ball")
{
Scoring.LifeLost();
//destroy it, and instantiate a new one above where the paddle currently is
Destroy(ball);
paddleObj.transform.position = new Vector2(0, -2.5f);
(Instantiate(ballPrefab, new Vector2(paddleObj.transform.position.x, paddleObj.transform.position.y + 0.3f), Quaternion.identity) as GameObject).transform.parent = paddleObj;
}
}
}
using UnityEngine;
using System.Collections;
public static class Scoring
{
public static GameObject scoreValue;
public static TextMesh scoreText;
public static int score;
static int multiplier = 0;
static int consecutiveBreaks = 0;
static int lives = 3;
static int totalBricks;
static int remainingBricks;
public static GameObject menuManagerObj;
public static MenuManager menuManager = new MenuManager();
static void Awake()
{
scoreValue = GameObject.FindGameObjectWithTag("Scoring");
scoreText = scoreValue.GetComponent<TextMesh>();
menuManagerObj = GameObject.FindGameObjectWithTag("MenuManager");
//menuManager = menuManagerObj.GetComponent<MenuManager>();
}
public static void BrickDestroyed()
{
if(scoreValue == null && scoreText == null)
{
scoreValue = GameObject.FindGameObjectWithTag("Scoring");
scoreText = scoreValue.GetComponent<TextMesh>();
}
remainingBricks--;
consecutiveBreaks++;
multiplier = 1 + (consecutiveBreaks % 5);
score += 10 * multiplier;
CheckGameOver();
scoreText.text = score + "";
}
public static void LifeLost()
{
consecutiveBreaks = 0;
multiplier = 1;
score -= 100;
lives--;
LivesDisplay.SetLives(lives);
CheckGameOver();
scoreText.text = score + "";
}
public static void SetBrickCount(int brickCount)
{
totalBricks = brickCount;
remainingBricks = totalBricks;
}
public static void CheckGameOver()
{
//lose condition
if(lives < 0) menuManager.ActivateLose();
//win condition
if(remainingBricks == 0) menuManager.ActivateWin();
}
}
using UnityEngine;
using System.Collections;
public class MenuManager : MonoBehaviour
{
public GameObject winMenu;
public GameObject loseMenu;
public GameObject pauseMenu;
public HighScoreManager highScores;
bool isGamePaused = true;
void Awake()
{
winMenu = GameObject.FindGameObjectWithTag("Win");
loseMenu = GameObject.FindGameObjectWithTag("Lose");
pauseMenu = GameObject.FindGameObjectWithTag("Pause");
}
public void ActivateWin()
{
Time.timeScale = 0f;
winMenu.transform.position = new Vector3(0, 0, -1);
highScores.CompareToHighScores(Scoring.score);
}
public void ActivateLose()
{
Time.timeScale = 0f;
loseMenu.transform.position = new Vector3(0, 0, -1);
}
void ActivatePause()
{
if(isGamePaused)
{
Time.timeScale = 0f;
pauseMenu.transform.position = new Vector3(0, 0, -1);
}
else
{
Time.timeScale = 1f;
pauseMenu.transform.position = new Vector3(35, 0, -1);
}
isGamePaused = !isGamePaused;
}
void Update()
{
if(Input.GetKeyDown(KeyCode.Escape))
{
ActivatePause();
}
}
}
The problem is that Scoring is not a MonoBehaviour so the Awake method never gets called. You can try to initialize the fields in a static constructor
static Scoring()
{
scoreValue = GameObject.FindGameObjectWithTag("Scoring");
scoreText = scoreValue.GetComponent<TextMesh>();
menuManagerObj = GameObject.FindGameObjectWithTag("MenuManager");
//menuManager = menuManagerObj.GetComponent<MenuManager>();
}
or make the Awake method public and call it from another MonoBehaviour.