I am having a weird issue with some of my code, and I could really use some help.
I have a script attached to a gameobject that is unique to a particular scene, so anything within Start() will only run when that scene is loaded. In this script, I am accessing Camera.main, since I use settings attached to the camera gameobject (it may sound inefficient, but it is necessary for the style of game we are creating). Anyway, if I start from that scene directly in Unity, it works just fine, but if I start from my intro scene and then load into the aforementioned scene, I get this error:
MissingReferenceException: The object of type 'Camera' 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.
The weird thing is, I can Debug.Log(Camera.main) and it gives me the name of the camera. So Camera.main is not null, and it is not destroyed like it says in the error message. Here is my full script:
private void Start()
{
Debug.LogError(Camera.main);
gameManager = FindObjectOfType<GameManagerScript>();
if (Camera.main == null)
{
Debug.LogError("Camera.main is null");
}
else
{
gameManager.LoadMusic(Camera.main);
gameManager.LoadAmbient(Camera.main);
gameManager.FadeStereoPan(Camera.main.gameObject.GetComponent<SwipeActivator>().stereoPanInNode);
}
}
The three functions above are custom functions I wrote, but I don't know why they would be causing the issue, since they work if I start up the scene directly.
I wasn't having this issue for months, and then all of a sudden, I am getting this error, even though I didn't change any of the code. Any help would be greatly appreciated.
I believe your MainCamera is being destroyed between scenes. Set it up as "DontDestroyOnLoad()"
See this Unity question:
https://answers.unity.com/questions/430141/need-the-same-main-camera-for-multiple-scenes.html
Ah, I fixed it. I dove into my custom functions and found that I was accessing a camera variable that is set at the beginning of the game, and then on each camera transition, but it was failing since I was loading a scene and no transitions that scene had yet to be completed. I just had to reassign that variable in the script above so it was not pointing to the destroyed object in the previous scene. Thank you JiveTurkey for pointing me in the right direction!
Related
Maybe im missing something obvious but to keep it short. I have working code for a character. When you "dash" I want to leave behind an after-image type effect, by cloning the player, removing its unneeded components and then applying a shader. Issue is as soon as I instantiate the clone the original player stops functioning (cant move etc). It still has all its components and everything as normal, and the clone does get the correct components removed. But it still breaks. As soon as I remove that line, its back to normal. Any ideas?
This is the only relevant code in the script that instantiates the clone.
private void DodgeEffect()
{
GameObject _DodgeSFX = Instantiate(gameObject, transform.position, transform.rotation );
Destroy(_DodgeSFX.GetComponent<PlayerController>());
Destroy(_DodgeSFX.GetComponent<PlayerCombat>());
Destroy(_DodgeSFX.GetComponent<WarpController>());
Destroy(_DodgeSFX.GetComponent<Animator>());
}
its because you are making a copy of gameObject. while Instantiate() returns a GameObject, it also returns whatever you put into the first section of the method. instead, make a seperate gameObject than the player in the editor, and make _DodgeSFX public so you can put the copy into the slot. Then, just instantiate that seperate GameObject and you wont have to destroy the components through script(because you remove the components in the editor), saving time
Ok so from some testing I think its down to the Unity.InputSystem only allowing 1 instance of each Input to be enabled at once. When I instantiated a clone of the player, it still goes through the Enable/Awake functions before those components are destroyed, and since the Inputs on that clone were never disabled, that becomes the "main" one. If I set the main player's scripts with Inputs deactive and then active again, it all works as normal. Note that the script was still working on the main character just fine, it was only the inputs that was broken. Im still not sure why this is the case, if its a limitation of the input system, or intentional, cant seem to find documentation of this experience anywhere.
I have an issue for which I've found a workaround, but can't understand why Unity isn't working the way I expect, or what I'm doing wrong. Basically, I am referencing a renderer component of a destroyed object in a script (long after it's been destroyed), and neither null checks nor type checks let me know it's destroyed.
I have a script that's modifying the shaders on some objects temporarily so I can apply effects on to them; when the effects are done it puts the materials/shaders back the way they were.
It happened that I was swapping out a character's weapon in the same frame I began one of these effects, so the script wound up with a reference to the renderer of a destroyed object (the old weapon). Many frames later when the effect was to finish, it naturally err'd out.
I tried a type check first to see if the reference was still to a renderer -- no luck. Unity's doc says a null check should work, but it still doesn't.
if (pair.Key != null && pair.Key is Renderer renderer) { renderer.materials = pair.Value; }
I get:
MissingReferenceException: The object of type 'SkinnedMeshRenderer' 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.
activeInHierarchy likewise does not work.
Adding a DestroyImmediate to the code where I destroy the object works fine; the object isn't there by the time the effect starts, so the reference is never made. However, that only solves this one problem, and not other such cases.
Can anyone tell me how to check properly for references to destroyed objects or components, or if I'm doing something wrong in my checking? Should I be referencing the gameObject instead of the renderer component or something like that?
EDIT:
Since a commenter asked for it, here's a gist of the full code for the effect. The destruction is happening outside this, as it's totally unrelated.
https://gist.github.com/jackphelps/f507d949a84c53457f570c5009bcb6d4
SOLVED -- SORT OF?
I changed the dictionary to store the renderer's game object instead of the renderer, and as expected a simple null check worked for detecting a destroyed object. I'd love to know why it doesn't work on the renderer, and if there's a proper way to check!
The best way I could find to solve this was to store a reference to the renderer's gameObject rather than to the renderer component itself. In this case, a simple null check at the end of the script works fine, as expected.
I'm not accepting this answer because it still doesn't tell me how to check for a component's presence when the game object was removed ¯(°_o)/¯
I have two Scenes in Unity. First one is for importing data from a binary file and after file is imported i create a gameobject with the coordinates i read from the binary file. I use DontDestroyOnLoad for this game object.
Then i load my second scene using AsyncOperation and find my object using GameObject.Find. This works fine and i can find the object and do my operations. However, in my second scene i have a reset button with which i reload the same scene using AsyncOperation. When scene is reloaded GameObject.Find can not find my object. By the way this only happens in Android build. In Editor it finds the object there is no problem.
This is how i reload the scene my ResetScene function gets called when button is pressed.
void ResetScene()
{
StartCoroutine(LoadAsyncScene());
}
IEnumerator LoadAsyncScene()
{
AsyncOperation asyncLoad = SceneManager.LoadSceneAsync("ARSession");
while (!asyncLoad.isDone)
{
yield return null;
}
}
Does anyone have any idea why this issue occurs or does anyone have a better idea for finding object? Since i create the object in runtime i feel like i have no option other than GameObject.Find. Any help would be appreciated. Thanks!
Note: I tried finding the object in Start and OnLevelWasLoaded. Both of them did not work.
I logged every game object in hierarchy using this:
foreach (GameObject obj in Object.FindObjectsOfType(typeof(GameObject)))
{
Debug.Log(obj.name);
}
In initial load my the game object i created is logged but after i reloaded the scene my object is not loaded.
I actually found the source of the problem. I was changing the parent
of my object from null to another object and apparently this causes
the issue. However, i do not know how to fix this because i must
change the parent i can't change that logic.
I actually found the solution. I did not realize the problem is caused because of changing the parent when i asked the question.
DontDestroyOnLoad only work for root GameObjects
Therefore, when i added a parent to my object my object is destroyed. Making the parent null alone was not enough. DontDestroyOnLoad has to be applied again. The solution i found was like this:
void ResetScene()
{
test.transform.parent = null;
DontDestroyOnLoad(test);
StartCoroutine(LoadScene());
}
After updating to Unity 2018.3.0f2 I`m unable to find a GameObjects prefab while the game is running. In the previous versions i was simply using this line:
GameObject prefabObject =
PrefabUtility.GetCorrespondingObjectFromSource(gameObject);
But after the update this function only returns null, so I tried the new functions:
PrefabUtility.GetPrefabInstanceHandle
PrefabUtility.GetNearestPrefabInstanceRoot
PrefabUtility.GetOutermostPrefabInstanceRoot
but all of them return null but I`m sure that I am handing a prefab over as parameter. Any ideas what I am doing wrong here?
As soon as editor start playing (Application.isPlaying=true) prefab linkage with scene game objects will be broken (blue game objects turned into gray) and thus you cannot obtain prefab related information from it.
If you really need a scenario were you want to access such information on runtime, you should save it as Serialized variable in script component so that it will later available on runtime.
For example: this is a simplified contraption of what Mirror (Unity network plugin) is doing by issuing asset ID related stuff to help distinguish each prefab to spawn things in network on runtime.
[SerializeField] string m_AssetId;
void OnValidate() // Which will be called on build or editor play
{
#if UNITY_EDITOR
// Deposit UnityEditor API dependent into some field
m_AssetId = UnityEditor.AssetDatabase.GetAssetPath( gameObject );
#endif
}
Anyway, for running editor script, if you want to test or look for original prefab. UnityEditor.PrefabUtility is somewhat hard to find a full example of how to use them.
You can refer to my git repository on how to use them with examples.
https://github.com/wappenull/UnityPrefabTester
I Need to apply DontDestroyOnLoad on Scene.is it possible?
I Need to Do not disturb the scene when going in to another scenes also.here i'm sending mail,when ever clicking send button its going to authentication in mail server in this time my scene idle means not responding anything until come back to the response from mail server,so on that time i show one loading bar in my scene.this is not do process.the entire scene is hang until came response from mail server,so how to solve this?
void Awake()
{
DontDestroyOnLoad(this.gameObject);
}
After reading so many non-answers I finally found the answer in a Unity forum. DontDestroyOnLoad ONLY works if the game object in question is at a "root level" meaning right under the scene, not nested under any other object. This is not mentioned anywhere in the documentation.
When loading a new level, scene, all Game Objects of the previous scene are destroyed by Unity.
If you want to protect a Game Object you can use the function.
DontDestroyOnLoad(gameObject);
It is important to note that when you say: this.gameObject you are pointing to pretty much the same thing, it just happens that this points directly to the script attached to that gameObject. So you don't need the this part, just gameObject will do.
Ideally you could protect that gameObject inside void Awake()
void Awake()
{
DontDestroyOnLoad(gameObject);
}
The above code will prevent Unity from destroying that gameObject unless your game closes completely or at a later point you call Destroy() on it. That means you can change from scene to scene and the gameObject will survive. However, if you make it back to the scene that creates that gameObject you are protecting you may run into problems if you do not have the logic implemented that prevents you from protecting a second, third, or many of that gameObject.
Your second question, if I understand it correctly:
You want to send mail when you change scenes, but your progress bar wont progress while changing scenes, it just stays there, static.
If that is the case then your problem is in Application.LoadLevel(sceneName); If you have the free version of Unity, then you need to come up with your own creative way of showing that progress bar, because Application.LoadLevel() will halt everything until it takes you to the new scene.
I don't completely understand what you are saying.
But because in your context, this in represents most probably a Monobehaviour, try the following:
void Awake() {
DontDestroyOnLoad(this.gameObject);
}
or
void Awake() {
DontDestroyOnLoad(gameObject);
}
See http://docs.unity3d.com/Documentation/ScriptReference/Object.DontDestroyOnLoad.html
I recommend you use a coroutine, with the 'yield' statement
check out this documentation of the WWW class, which likewise involves writing code to cope with waiting for a response from the web, without hanging your Unity3d program
coroutines are pretty powerful if you're working with tasks that take more than a frame or two. Richard Fine (AltDevBlog) has posted a really detailed description of what they are and how to use them, which I thoroughly recommend.