I am trying to move my player to destroy monsters and the first time I destroy a monster I have the following error:
MissingReferenceException: The object of type 'GameObject' has been destroyed but you are still trying to access it.
Your script should either check if it is null or you should not destroy the object.
How can I make it to duplicate itself as a new GameObject?
This is my script:
using System.Collections.Generic;
using UnityEngine;
public class TimeMap: MonoBehaviour {
public GameObject selectedUnit;
public GameObject selectedMonster;
public TileType[] tileTypes;
try{
if(selectedMonster.GetComponent<Monster>().tileX == selectedUnit.GetComponent<Unit>().tileX && selectedMonster.getComponent<Monsters>().tileY == selectedUnit..GetComponent<Unit>())
Destroy(selectedMonster);
}
public void SpawnMon() {
if(counter % 5 == 0){
Debug.Log(" counter % 5 == 0");
Instantiate(selectedMonster.GetComponent<Monsters>().Monster, new Vector3(Random.Range(1,8), Random.Range(1,8), -1), Quaternion.identity);
}
}
}
So I try to create the same object or a clone of it every 5 moves, but I am having errors while doing it.
Problems:
You are trying to access your monsters like this:
selectedMonster.GetComponent<Monster>()
It means if you have in your scene more than one GameObject of type Monster, Unity will not be sure which one you are referring to.
Also when you instantiate a monster, you use just
Instantiate(selectedMonster.GetComponent<Monsters>().Monster, new Vector3(Random.Range(1,8), Random.Range(1,8), -1), Quaternion.identity);
So you will not be able to distinguish one instance from another in your scene.
Solutions:
In case you wanted to continue with this approach, where you check if tileX and tileY of monster match with your Unit (which I assume is your hero or similar), you should have all monsters inside an array so you can iterate them all in a way you refer easily to the one you want to destroy.
You could try FindObjectsOfType and there pass your Monster type:
Monster [] monsters= FindObjectsOfType(typeof(Monster )) as Monster [];
Then you iterate
foreach (Monster thisMonster in monsters){
//check things here
}
Another option is to store the monsters in an array when you instantiate them
//Define as global variable a list of Monsters
List<GameObject> monsterList = new List<GameObject>();
//Then you instantiate then like
monsterList .add((GameObject)Instantiate(selectedMonster.GetComponent<Monsters>().Monster, new Vector3(Random.Range(1,8), Random.Range(1,8), -1), Quaternion.identity));
And you iterate them using the foreach as before
Better Solution (From my point of view)
However, since your main goal, correct me if I am wrong, is to detect when the position of a Unit match with the position of a monster, to later destroy that particular monster. I would use colliders instead. And in the GameObject you call Unit I would add a TriggerEnter. Since you use the TileX and TileY I suspect you are creating a 2D game, so it would be something like this:
void OnTriggerEnter2D(Collider2D other) {
Destroy(other.gameObject);
}
With this you destroy any monster that touches your "Unit" and you will not have reference problems.
Related
I would like some help with figuring this out as my brain is having a funny day today at what is the best way to go about this.
I have an OnDrawGizmos as follows
Transform parentBounds;
void OnDrawGizmos()
{
parentBounds = this.gameObject.transform;
Vector3 from;
Vector3 to;
for (int a = 0; a < parentBounds.childCount; a++)
{
from = parentBounds.GetChild(a).position;
to = parentBounds.GetChild((a + 1) % parentBounds.childCount).position;
Gizmos.color = new Color(1, 0, 0);
Gizmos.DrawLine(from, to);
}
}
This code is attached on a "parent" object which contains 4 empty game objects as follows
Which produces the following Gizmo (Drawing a square based on where I put the empty objects within the parent)
I can even add more points if I desire.
SO WHAT IS THE PROBLEM ?
What I need is that if the player is not within this box area, I want the player to be destroyed. I'm not sure what the best practice is for this , should I make an array to hold the xmin, ymax, etc. ? or should I generate a new position vector on every loop ? I've tried a few ways that are not giving me the results I want and I taught to ask for some assistance.
Thank you all in advance !
If this is a 2D game (which I assume it is), how about having a script, that has reference to the player object and...
a) game is not using physics
... a public Rect boundaries. On each Update() check if player is within the boundaries and if not - destroy it.
void Update()
{
if (!boundaries.Contains(playerObject.transform.position))
{
Destroy(playerObject);
}
}
b) game is using physics
... a BoxCollider2D with the following script
void OnColliderExit2D(Collider2D collider)
{
// If collider is player object -> destroy collider.gameObject
}
I have a problem with my script. I'm really looking for a solution without having to post code. ( I'm using Unity 2019 with C#. )
Here's the dilemma:
I have two scripts
1) EnemyDamage
2) EnemySpawn
Both scripts work fine until one of the enemies is killed.
Basically when my enemy('s) die I use Destroy(gameObject) which ultimately is causing the error on my spawn script because the EnemySpawn is still trying to access the destroyed enemy.
The way my spawn script works is multiple enemies can be chosen from a list. Then using coroutines, the enemies appear on screen and then disappear using SetActive(true/false). So even if I elect to set the enemy to false in EnemyDamage, the EnemySpawn will just set it back to true.
So what I need is another way to hide my enemy. ( And I can't just move it out of camera sight because the EnemySpawn will just put it back on a random spawn point in camera view again )
What are some alternatives to Destroy(), SetActive(), or moving out of camera range?
Try adding this in the the spawn enemy script. It should remove an enemy from the list when that enemy is destroyed .The enemysToRemove variable is there because you cant edit a list while iterating through it (thanks Hristo).
public List<GameObject> enemys;
List<GameObject> enemysToRemove = new List<GameObject>();
void Update () {
foreach(GameObject enemy in enemys){
if (enemy == null) {
enemysToRemove.Add (enemy);
}
}
foreach (GameObject item in enemysToRemove) {
enemys.Remove (item);
}
}
Alternatively, put try and catch in-front of everything you do to the enemy`s in the spawn enemy script. Like this:
public List<GameObject> enemys;
foreach(GameObject enemy in enemys){
try{
//thing I want to do to this enemy
}catch{
Debug.Log ("enemy destroyed");
}
}
Using Unity, I'm working on a game where all Gameobjects with a certain tag vanish/reappear fairly regularly (every 10 seconds on average). I use GameObject.FindGameObjectsWithTag() to create a Gameobject[] through which I enumerate every time that the objects need to be made visible/invisible. I cannot call it once, on Start, as new Gameobjects are created while playing. I thought that it would be worse to access and change the Gameobject[] every time something got created/destroyed. Is there a better way to handle this. I know how bad of an impact on performance the GameObject.Find methods make...
Yes, there is a better way to do this. Have a script with List variable that can store GameObjects. Making it a singleton is better but not necessary.
This singleton script should be attached to an empty GameObject:
public class GameObjectManager : MonoBehaviour
{
//Holds instance of GameObjectManager
public static GameObjectManager instance = null;
public List<GameObject> allObjects = new List<GameObject>();
void Awake()
{
//If this script does not exit already, use this current instance
if (instance == null)
instance = this;
//If this script already exit, DESTROY this current instance
else if (instance != this)
Destroy(gameObject);
}
}
Now, write a script that registers itself to the List in the GameObjectManager script. It should register itself in the Awake function and un-register itself in the OnDestroy function.
This script must be attached to each prefab you want to add to the List. Simply do that from the Editor:
public class GameObjectAutoAdd : MonoBehaviour
{
void Awake()
{
//Add this GameObject to List when it is created
GameObjectManager.instance.allObjects.Add(gameObject);
}
void OnDestroy()
{
//Remove this GameObject from the List when it is about to be destroyed
GameObjectManager.instance.allObjects.Remove(gameObject);
}
}
If the GameObjects are not prefabs but GameObjects created through code, simply attach the GameObjectAutoAdd script to them once they are created:
GameObject obj = new GameObject("Player");
obj.AddComponent<GameObjectAutoAdd>();
You can now access your GameObjects in the List with GameObjectManager.instance.allObjects[n]; where n is the index number and you don't have to use any of the Find functions to find the GameObject anymore.
It's true that calling to GameObject.Find consumes a lot of recourses.
The point should be to save the result and use it always but I understand that you can't do that.
Other option is to have all this gameobjects as a child of one gameobject let's call it handlerGameobject. It will have a script that doesn't use GameObeject.Find it could getChild or transform.Find that uses less resources.
Hope it helps!
this is the code where the problem is situated:
public class EnemySpawnScript : MonoBehaviour {
private float previousEnemyDelay = 0;
public void enemySpawn (GameObject player, LevelData level){
//loop every enemy inside the level to instantiate them. EnemyDataSpawn has got some infos about every enemy
foreach (EnemyDataSpawn enemyDataSpawn in level.enemyDataSpawner) {
StartCoroutine (InstantiateObject (player,enemyDataSpawn));
}
}
IEnumerator InstantiateObject (GameObject player, EnemyDataSpawn enemyDataSpawn)
{
//this handles the delay of the spawn of every enemy.
previousEnemyDelay += enemyDataSpawn.delay;
//here is the problem if i want to stop enemies to spawn and then continue to spawn them again.
yield return new WaitForSeconds (previousEnemyDelay);
//after waiting, i do something.
}
This code works if I just want to instantiate every enemy after a delay specified inside enemyDataSpawn (I didn't write the "instantiate enemy" part (i used object pooling to achieve that), situated after the yield inside IEnumerator because it's not important for my problem).
The problem is that i have an integer (called maxOnScreen) for every kind of enemy, and if the number of the ACTIVE enemies with the same name is equal to maxOnScreen, then i want to stop to instantiate every other enemy until one enemy (which active number was equal to maxOnScreen) will be deactivated or destroyed. If one enemy is not activated anymore and the number of active enemies with the same name is not equal to maxOnScreen anymore, than I want to instantiate the next enemy in the list again with his delay as my actual code already does. I don't know how to achieve this with IEnumerator so my question is: is it possible to achieve this with IEnumerator or i should use some other methods?
Simple example: there are 7 enemies active, 3 named "bad soldier" and 4 named "good soldier". The maxOnScreen variable of good soldier is "4" so i don't want that other enemies will instantiate unless one of "good soldier" will be destroyed/deactivated. If the total of active "good soldier" is 3 (so less than maxOnScreen again), i want that the game goes on spawning the remaining enemies to spawn.
Thank you in advance
You might use a single enemy-spawning coroutine instead of launching each coroutine for each enemy you want to spawn. This way you can easily control when to spawn an enemy and when to delay its spawning:
public class EnemySpawnScript : MonoBehaviour {
public void enemySpawn (GameObject player, LevelData level){
StartCoroutine(InstantiateObjects(player, level.enemyDataSpawner));
}
IEnumerator InstantiateObjects (GameObject player, IEnumerable<EnemyDataSpawn> enemyDataSpawnList){
foreach(var enemyDataSpawn in enemyDataSpawnList){
while( /* too many enemies of enemyDataSpawn type */ ) {
yield return new WaitForSeconds(enemyDataSpawn.delay);
}
// instantiate enemyDataSpawn
}
}
}
This is semi complicated of a question but I'll do my best to explain it:
I am making this mobile game in which you have to shoot four cubes. I'm trying to make it so when the cubes are shot by a bullet, they're destroyed and a UI text says 1/4, to 4/4 whenever a cube is shot. But it's being really weird and only counts to 1/4 even when all four cubes are shot and destroyed. I put these two scripts on the bullets (I made two separate scripts to see if that would do anything, it didn't)
And to give a better idea of what I'm talking about, here's a screenshot of the game itself.
I've been using Unity for about 6 days, so I apologize for anything I say that's noob-ish.
EDIT
So I combined the two scripts onto an empty gameobject and here's the new script:
using UnityEngine;
using System.Collections;
using UnityEngine.UI;
public class GameManagerScript : MonoBehaviour {
public GameObject cubes;
public Text countText;
public int cubeCount;
public Transform target;
// Use this for initialization
void Start () {
}
void OnTriggerEnter(Collider other)
{
cubes = other.gameObject;
}
// Update is called once per frame
void Update () {
cubes.transform.position = Vector3.MoveTowards(transform.position, target.position, 1f * Time.deltaTime);
if (cubes.gameObject.tag == "BULLET")
{
cubeCount = cubeCount + 1;
countText.text = cubeCount + "/4";
cubes.SetActive(false);
}
}
}
ANOTHER EDIT
I tried everything, so is there a way to detect when all the children in a parent on the Hierarchy are destroyed? Instead of counting up? This can give a better idea:
So I want to be able to detect when Cube, Cube1, Cube2, and Cube3 have all been destroyed.
The answer is pretty simple: Since every individual bullet has that script, each bullet has its own score.
For something like a score you want a single spot to store it, e.g. a script on an empty gameobject that serves as game controller. Just access that in the collision and increase the score (maybe have a look on singletons here).
You can combine those two scripts and actually it might be better to not have this on the bullet, but on the target because there are probably less of them which will save you some performance. (And it does more sense from a logical point of view.)
Edit:
I assume you create the bullets using Instantiate with a prefab. A prefab (= blueprint) is not actually in the game (only objects that are in the scene/hierarchy are in the game). Every use of Instantiate will create a new instance of that prefab with it's own version of components. A singleton is a thing that can only exist once, but also and that is why I mention it here, you can access it without something like Find. It is some sort of static. And an empty gameobject is just an object without visuals. You can easily create one in unity (rightclick > create empty). They are typically used as container and scriptholders.
Edit:
What you want is:
An empty gameobject with a script which holds the score.
A script that detects the collision using OnTriggerEnter and this script will either be on the bullets or on the targets.
Now, this is just a very quick example and can be optimized, but I hope this will give you an idea.
The script for the score, to be placed on an empty gameobject:
public class ScoreManager : MonoBehaviour
{
public Text scoreText; // the text object that displays the score, populate e.g. via inspector
private int score;
public void IncrementScore()
{
score++;
scoreText.text = score.ToString();
}
}
The collision script as bullet version:
public class Bullet : MonoBehaviour
{
private ScoreManager scoreManager;
private void Start()
{
scoreManager = GameObject.FindWithTag("GameManager").GetComponent<ScoreManager>(); // give the score manager empty gameobject that tag
}
private void OnTriggerEnter(Collider other)
{
if(other.CompareTag("Target") == true)
{
// update score
scoreManager.IncrementScore();
// handle target, in this example it's just destroyed
Destroy(other.gameObject);
}
}
}