I don't know what is wrong with my destroy portion of the below code. I'm trying to have only 1 GameControl persist throughout the scenes. It seems that every time I switch back to this scene, my GameControl is read as null and a new GameControl is generated and I end up having more than 1 GameControl persisting.
For reference: I tried to port the code from 18:24 to JavaScript from this link
Please advise.
#pragma strict
var control : GameControl;
function Awake () {
Debug.Log("GameControl runs");
if (control == null)
{
DontDestroyOnLoad(gameObject);
control = this;
Debug.Log(control);
} else if (control != this)
{
Destroy(gameObject);
Debug.Log("Destroy?");
}
}
function Update ()
{
}
The problem is that you're not using a static variable like this:
static var control : GameControl;
In simple terms being static means this variable will hold the same value across all your scripts thus the check if(control == null) will always remain true because your GameObject will create a new variable when you load a new scene. This new object is still not static and is therefore completely different. I hope this helps. If you are still confused I'd advise reading some single pattern articles because there are many ways to achieve it other than this.
Related
I'm making a game where the player can switch back and forth between levels. I use "DontDestroyOnLoad" to bring my player between them, but whenever I reload a scene, it duplicates the player, as well as everything else I want to keep loaded. Does anyone know any easy fix to this? I'm new to programming so keep it simple please.
probably you need to write something like this:
public static <TypeName> instance = null;
void Awake() {
if (instance != null) {
Destroy(gameObject);
} else {
instance = this;
DontDestroyOnLoad(gameObject);
}
}
For my game you need to complete a mini-game to unlock abilities. But I atually have no clue how to do it cause the value gets resetted to false whenever I load the main-level.
Code playerMovement:
static bool FistAttackEnabled;
void Update ()
{
if (FistAttackEnabled == true)
{
if (Input.GetMouseButtonDown(0))
{
Debug.Log("Attack");
PlayerMovement.SetFloat("Attacking", 1f);
HitArea.SetActive(true);
}
}
}
Code miniGame:
void Start()
{
FistAttackEnabled = Player.GetComponent<Player_Movement>().FistAttackEnabledPortable;
}
void Update()
{
if (SheepsAmountGuess == NeededAni)
{
FistAttackEnabled = true;
}
}
But this doesnt work. I tried making a portable bool (FistAttackEnabledStatic = FistAttackEnabled) Because you cant transport static bool value's across scripts, but this also didn't work. Does anyone have a clue how to do it?
PS: The code is bigger but it doesn't have anything to do with the attack.
Each time the scene is loaded the scripts are reloaded, so variables will go to their "default" state
You can avoid the destruction of the gameObject by usign DontDestroyOnLoad(this.gameObject);
Since the GameObject wont be deleted each time you reload the scene a new copy will be created to solve that you should use a singleton(look for it you will find information easyly)
Both things will solve the problem temporaly but once you close the game everything will go to the original state. You should use some method to save the progress, PlayerPrefs is a really easy way to do it.
I search a lot but couldn't find any answer. My problem: I instantiate several Gameobjects of a Prefab, each consists of two child objects: an obstacle and a scorezone. I want to destroy the scorezone (only of that specific instance), when the player touches the obstacle. So in Runtime my hierarchy looks like this:
-ObjectPrefab(clone)
---Scorezone
---Obstacle
-ObjectPrefab(Clone)
---Scorezone
---Obstacle
...
So I need to find ONE child gameobject (not the Transform) to then destroy it. I tried several codes but none worked. Here is the code with the three alternatives I tried, but none of them worked.:
private void OnCollisionEnter2D(Collision2D collision) {
if (collision.gameObject.tag == "obstacle") {
Alternative 1:
Destroy(GameObject.FindWithTag("scorezone"));
Alternative 1 comes really close, but it destroys all scorezones of all instantiated objects.
Alternative 2:
Destroy(collision.gameObject.transform.parent.gameObject.FindWithTag("scorezone"));
Alternative 2 would sound logic to me but I get the error message "Transform does not contain a definition for "FindWithTag".
Alternative 3:
foreach (Transform child in collision.gameObject.transform)
{
if (child.tag == "scorezone")
{
Destroy(child.gameObject);
}
}
}
Alternative 3 does not give an error but actually does nothing at all when the player hits the obstacle.
I really appreciate some help, thanks in advance!
Store the reference!
If it is really a "prefab" so meaning you have it as an asset and instantiate it on runtime the best way (in my eyes and performance wise) would actually be to use a serialized field:
// Put this component on your obstacle
public class ObjectController : MonoBehaviour
{
// Drag the according object here via the Inspector in the prefab
// => when the prefab is Instantiated this field is already referenced
[SerializeField] private GameObject _scoreZone;
// Read-only access to the reference
public GameObject ScoreZone => _scoreZone;
}
This field reference is stored together with your prefab asset. So every instance of the prefab already has its own child references set up.
and then do
private void OnCollisionEnter2D(Collision2D collision)
{
// Rather use CompareTag which is slightly more efficient
// and adds some security (== silently fails if typo, CompareTag throws an exception instead)
if (collision.gameObject.CompareTag("obstacle"))
{
var controller = collision.gameObject.GetComponent<ObjectController>();
if(controller)
{
Destroy(controller.ScoreZone);
}
}
}
By Index
Alternatively but error prone you could simply use the index. You already know that there are only 2 childs, the first one being the Scorezone with index 0 so you can also do
if (collision.gameObject.CompareTag("obstacle"))
{
var scoreZone = collision.transform.parent.GetChild(0);
Destroy(scoreZone);
}
By Name
Using the name you could also use Find - I would not recommend this! It is error prone and slow
if (collision.gameObject.CompareTag("obstacle"))
{
var scoreZone = collision.transform.parent.Find("ScoreZone");
Destroy(scoreZone);
}
I made a pretty basic 2D game to learn. I have 2 Scenes, and switching between them worked great. I used empty gameObjects as Start/Exit point of the Scene, so that the game would know to put player on point X after exiting through point X (for example exit outside house if I walk out the door).
Then I added a "Scene0", to use for persistent general scripts like GameManager, Sounds, Music, etc. With just one object called "Controller" that I DontDestroyOnLoad().
After adding this Scene and then just switching Scenes right away to my MainScene, all of a sudden the game starts acting really strange;
the first time I move from my MainScene (Scene1), to my secondary Scene (Scene2), it works fine, but then when I leave Scene2 to go back to Scene1, the player spawns in the middle of nowhere.
And this ONLY happens if I launch the game from my Persistent Scene.
I have no idea what is wrong, I don't add anything that interferes with my scene transitions, all I've added so far is playerHealth, for testing.
Scripts attached to my (persistent) Controller:
DDOL:
public class DDOL : MonoBehaviour {
// Use this for initialization
void Awake () {
DontDestroyOnLoad (gameObject);
}
}
GameManager:
public class GameManager : MonoBehaviour {
public static GameManager manager;
public int playerMaxHealth;
public int playerCurrentHealth;
void Awake(){
if (manager == null) {
manager = this;
} else if (manager != this) {
Destroy (gameObject);
}
}
// Use this for initialization
void Start () {
SceneManager.LoadScene("test_scene");
}
// Update is called once per frame
void Update () {
}
}
Scripts attached to my StartPoint:
PlayerStartPoint:
public class PlayerStartPoint : MonoBehaviour {
private PlayerController thePlayer;
private CameraController theCamera;
public Vector2 startDir;
public string pointName;
// Use this for initialization
void Start () {
thePlayer = FindObjectOfType<PlayerController> ();
if (thePlayer.startPoint == pointName) {
thePlayer.transform.position = transform.position;
thePlayer.lastMove = startDir;
theCamera = FindObjectOfType<CameraController> ();
theCamera.transform.position = new Vector3(transform.position.x, transform.position.y, theCamera.transform.position.z);
}
}
}
And finally ExitPoint:
LoadNewArea:
public class LoadNewArea : MonoBehaviour {
public string levelToLoad;
public string exitPoint;
private PlayerController thePlayer;
// Use this for initialization
void Start () {
thePlayer = FindObjectOfType<PlayerController> ();
}
void OnTriggerEnter2D(Collider2D other){
if (other.gameObject.name == "Player")
{
SceneManager.LoadScene(levelToLoad);
thePlayer.startPoint = exitPoint;
}
}
}
EDIT:
After moving all my DDOL gameObject to the Pre-Scene, it worked. So, I can assume the fault is inside Player or Cameras Start() functions since when they start in Scene1 they get called every time I enter the Scene (only DDOL).
I tried adjusting their Start()functions like follows:
Original camera:
void Start () {
Debug.Log("Starting camera");
if (!cameraExists) {
cameraExists = true;
DontDestroyOnLoad (gameObject);}
else{
Destroy (gameObject);
}
}
Changed Camera:
void Start () {
DontDestroyOnLoad (gameObject);
}
The exact same changes was made in Player.
Obviously this doesnt work because it creates a new Camera/Player every time I enter Scene1 (btw why does it not try to create them when I enter Scene2?, is it because they start in Scene1?). HOWEVER, the new player/camera do start at the correct position, and if I zoom out I can see the old player/camera at that same wrong position as before. So something weird happens when their Start() is called a second time it seems.
You've now mentioned that you had code something like this,
void Start () {
Debug.Log("Starting camera");
if (!cameraExists) {
cameraExists = true;
DontDestroyOnLoad (gameObject);}
else{
Destroy (gameObject);
}
}
Note that this is unfortunately just "utterly incorrect", heh :)
The issues you mention in the question (preload scenes etc) are just totally unrelated to the problem here.
In Unity if you have a character C that persists between scenes a, b, c as you load those scenes, you must kick-off C in it's own (perhaps otherwise empty) scene, you can not use "a" as a matter of convenience to kick off C.
The pattern is, in each of a, b, c just have a line of code like p = FindObjectOfType<Player>(); which runs when the scene loads, and position C as you wish.
Now, regarding your specific puzzle about the unusual behavior you are seeing.
I understand that you want to know why you are observing what you do.
It is a combination of confusion over the following issues: 1 - difference between Awake and Start, 2 - confusion over script execution order {but see below1} 3 - confusion about Destroy versus DestroyImmediate 4 - Not using Debug.Log enough, and not using gameObject.name in there (it's a common in Unity to be wildly confused about which object is talking in Debug.Log) 5 - where you mention you see the other object "off to the side", it's common to drastically confuse which one is which in such situations 6 - confusion between the computer programming concept of "instantiation" (ie, of a class or object) and "instantiating" (confusingly, it's the same word - utterly unrelated) game objects in nity.
If you fiddle around with all those issues, you'll discover an explanation for the behavior you're seeing!
But it doesn't amount to much; in Unity in the "C .. a b c" example you have to create C separately beforehand.
1 {aside, never fiddle with the script execution ordering system in Unity in an effort to solve problems; it's only there for R&D purposes; however it could in fact help you investigate the behavior at hand in this problem, if you are particularly keen to fully understand why you're seeing what you're apparently seeing}
Use the debugger. Have breakpoints at the relevant spots, like PlayerStartPoint.Start() and LoadNewArea.OnTriggerEnter2D() and check that they are executed
At the right time
The right number of times
With the expected values
This should make you see where things get out of hand.
If you use Visual Studio, install https://marketplace.visualstudio.com/items?itemName=SebastienLebreton.VisualStudio2015ToolsforUnity to be able to debug Unity from within Visual Studio.
If you are not using Visual Studio, you probably should.
Is player persistent between scenes (does he have DontDestroyOnLoad)? If no then this might be the reason - you can either try loading the scenes by using the additive mode or by instantiating the player on scene load in correct position.
I'm learning unity scripting. But I don't understand the following :
static private var lastRecalculation = -1;
static function RecalculateValue () {
if (lastRecalculation == Time.frameCount)
return;
ProcessData.AndDoSomeCalculations();
}
I don't get the third line or the condition in the IF statement. I know its a bit amateur, but pls help.
Thank You.
This is from the Time.frameCount documentation. This example shows how to create a function that executes only once per frame, regardless of how many objects you attach your script to. I suspect though that this example is incomplete because it never updates lastRecalculation (or it was assumed you would do so in AndDoSomeCalculations() ).
The reason setting lastRecalculation = -1 initially is so this function runs during the first frame.
Working version:
static var lastRecalculation = -1;
static function RecalculateValue () {
if (lastRecalculation == Time.frameCount) {
return;
}
lastRecalculation = Time.frameCount;
Debug.Log (Time.frameCount);
//ProcessData.AndDoSomeCalculations();
}
function Update () {
RecalculateValue();
}
Attach this script to 2 different GameObjects and run it. You will only see unique frame values 1,2,3,4,5.... even though 2 GameObjects are each calling RecalculateValue()
Now comment out the return and run it again. Now the ProcessData portion of that code runs for both objects every frame and you'll see something like 1,1,2,2,3,3,4,4......