Unity3D Prevent adding certain built-in components - c#

I have made my own component which conflicts with some Unity built-in components (like Rigidbody conflicts with Rigidbody2D). So I need to be sure that those components will not exist together in the same GameObject. Is there a way to do it? It seems to be easy to check when my own component is added (by Reset), but what to do if Unity' built-in component is added? Is there some callback, message, or event sent when new component attached to the GameObject?
Precisions
I do not need to hide components it in the editor, or prevent adding my own components. I am asking about preventing adding certain Unity' built-in components while my component is attached. From both Editor GUI (by "add component" button) and Unity API (by GameObject.AddComponent).

There is the [DisallowMultipleComponent] attribute which prevents two of the same type from being added to the same game object. This works for subtypes as well (which is how Rigidbody and Rigidbody2d are handled).
I am not sure if this will work for you or not, as you haven't said your components are related to each other, but it is what I can find.

Is there some callback, message, or event sent when new component
attached to the GameObject?
No.
Is there a way to do it?
Yes, but a bit complicated.
If you want to prevent your custom script from being added, that would have been easy and this question should handle that.
This is complicated because you want to prevent a component written by another person(built-in) from being added to a GameObject which means that you first need a way to detect when that component has been added to a GameObject then destroy it. This has to be done every frame (Both in the Editor and during run-time).
You can call the components you don't want to be added to a GameObject blacklisted components.
Here are the steps:
1.Store the blacklisted components in an array.
private static Type[] blacklistedComponents =
{
typeof(Rigidbody),
typeof(Rigidbody2D)
//...
};
2.Get the root GameObjects in the scene and store them in a List.
private static List<GameObject> rootGameObjects = new List<GameObject>();
Scene.GetRootGameObjects(rootGameObjects);
3.Loop through each root GameObject and use GetComponentsInChildren to get all the components attached to each GameObject under that root GameObject.
private static List<Component> allComponents = new List<Component>();
currentLoopRoot.GetComponentsInChildren<Component>(true, allComponents);
4.During the loop from #3, loop through the retrieved components and check if it has any blacklisted component. If it does, destroy that blacklisted component.
for (int i = 0; i < allComponents.Count; i++)
{
//Loop through each blacklisted Component and see if it is present
for (int j = 0; j < blacklistedComponents.Length; j++)
{
if (allComponents[i].GetType() == blacklistedComponents[j])
{
Debug.Log("Found Blacklisted Component: " + targetComponents[i].GetType().Name);
Debug.Log("Removing Blacklisted Component");
//Destroy Component
DestroyImmediate(allComponents[i]);
Debug.LogWarning("This component is now destroyed");
}
}
}
That's it. You or others may have few questions about this answer.
Q 1.Wonder why FindObjectsOfType and FindObjectsOfTypeAll are not used?
A 1.These functions are usually used to simplify getting everything in the scene but the problem is that they return array. Calling these functions every frame will kill your game performance since it allocates memory and will cause garbage collector to run more often.
This is why Scene.GetRootGameObjects is used which you can pass a List inside it and it will fill the list for you. It does not return array.
Q 2.Why did you pass List to GetComponentsInChildren and not return the result from it?
A 2. Technically the-same reason I explained above. I used a version of the GetComponentsInChildren function that does not allocate memory. Simply pass List to it and it will fill it up with every component it found. This prevents it from returning an array which is expensive.
I wrote a complete working code for this below but you need to improve it. That's why I explained every process so that you can either improve or rewrite it yourself. It currently prevents Rigidbody and Rigidbody2D from being added from the Editor or from code in the Editor or in a build.You can add more components you want to block to the blacklistedComponents variable. It runs in the Editor also during runtime. UNITY_EDITOR is used to remove the Editor codes and make sure that it compiles for platforms.
1.Create a script called ComponentDetector and copy every code below into it.
2.Save and go back to the Editor. That's it. You don't have to attach it to any Object. You should never be able to add Rigidbody and Rigidbody2D to any GameObject.
using System.Collections.Generic;
using UnityEngine;
using System;
using UnityEngine.SceneManagement;
#if UNITY_EDITOR
using UnityEditor;
#endif
public class ComponentDetector : MonoBehaviour
{
//Add the blacklisted Components here
private static Type[] blacklistedComponents =
{
typeof(Rigidbody),
typeof(Rigidbody2D)
//...
};
private static List<Component> allComponents = new List<Component>();
private static List<GameObject> rootGameObjects = new List<GameObject>();
private static void GetAllRootObject()
{
Scene activeScene = SceneManager.GetActiveScene();
activeScene.GetRootGameObjects(rootGameObjects);
}
private static void GetAllComponentsAndCheckIfBlacklisted()
{
for (int i = 0; i < rootGameObjects.Count; ++i)
{
GameObject obj = rootGameObjects[i];
//Debug.Log(obj.name);
//Get all child components attached to this GameObject
obj.GetComponentsInChildren<Component>(true, allComponents);
//Remove component if present in the blacklist array
RemoveComponentIfBlacklisted(allComponents, blacklistedComponents);
}
}
private static void RemoveComponentIfBlacklisted(List<Component> targetComponents, Type[] blacklistedList)
{
//Loop through each target Component
for (int i = 0; i < targetComponents.Count; i++)
{
//Debug.Log(targetComponents[i].GetType());
//Loop through each blacklisted Component and see if it is present
for (int j = 0; j < blacklistedList.Length; j++)
{
if (targetComponents[i].GetType() == blacklistedList[j])
{
Debug.Log("Found Blacklisted Component: " + targetComponents[i].GetType().Name);
Debug.LogError("You are not allowed to add the " + targetComponents[i].GetType().Name + " component to a GameObject");
Debug.Log("Removing Blacklisted Component");
//Destroy Component
DestroyImmediate(targetComponents[i]);
Debug.LogWarning("This component is now destroyed");
}
}
}
}
public static void SearchAndRemoveblacklistedComponents()
{
//Get all root GameObjects
GetAllRootObject();
//Get all child components attached to each GameObject and remove them
GetAllComponentsAndCheckIfBlacklisted();
}
void Awake()
{
DontDestroyOnLoad(this.gameObject);
}
// Update is called once per frame
void Update()
{
//Debug.Log("Update: Run-time");
SearchAndRemoveblacklistedComponents();
}
}
#if UNITY_EDITOR
[InitializeOnLoad]
class ComponentDetectorEditor
{
static ComponentDetectorEditor()
{
createComponentDetector();
EditorApplication.update += Update;
}
static void Update()
{
//Debug.Log("Update: Editor");
ComponentDetector.SearchAndRemoveblacklistedComponents();
}
static void createComponentDetector()
{
GameObject obj = GameObject.Find("___CDetector___");
if (obj == null)
{
obj = new GameObject("___CDetector___");
}
//Hide from the Editor
obj.hideFlags = HideFlags.HideInHierarchy;
obj.hideFlags = HideFlags.HideInInspector;
ComponentDetector cd = obj.GetComponent<ComponentDetector>();
if (cd == null)
{
cd = obj.AddComponent<ComponentDetector>();
}
}
}
#endif

If you're trying to determine if the component exists before runtime, which I assume you already know, you can use the Start() method. But, like I said, I assume you already know that, so the only other way to check something like that during runtime would be to continually check for it in the Update() method, every frame. Although, I am not sure as to why a Unity component might be added to a gameobject during runtime. If this is an issue, maybe the component in question could be added to a child or parent gameobject instead?
If you really feel like making some changes, which may require a lot of refactoring for your project, you could always create a ComponentManager class that handles adding and removing components to GameObjects and create your own callbacks.

Related

How do I access a prefab and all of its instantiated clones in c# and unity?

I need a little help again please. I'm currently working on powerups and it's setup so that the powerup affectsthe prefab thats put into its prefab slot, so this is means it is currently only affecting one object (in my case, enemy). When the game starts I spawn about 20 enemies and if i pickup the powerup I want it to affect all those spawned enemies and not only the one that is dragged onto the script, does anyone have a solution or alternate method to do this please?
When instantiate them store them in a list and then iterate through all and update their value
In your case e.g.
// if enemies have a certain Component rather use that type here instead of GameObject
public GameObject enemyPrefab;
// and use the same type here instead of GameObject
private List<GameObject> enemyInstances = new List<GameObject> enemyInstances;
private void Start()
{
for(int i = 0; i < 20; i++)
{
var newEnemy = Instantiate(enemyPrefab);
enemyInstances.Add(newEnemy);
}
}
and then later
public void UpdateEnemies()
{
foreach(var enemy in enemyInstances)
{
// skip already destroyed objects
if(!enemy) continue;
// whatever to be done to the enemies
}
}
To get all game objects to an array you can use the Tag.
Just add an 'Enemy' tag to the prefab and use the code below:
public GameObject[] enemys;
void Start()
{
respawns = GameObject.FindGameObjectsWithTag("Enemy");
}
Full Unity documentation HERE

How to add Script to instantiated object at runtime?

I have a Script in my main Assets folder called BezierWalk.cs
In another script, Spawn, I'm trying to instantiate objects from Prefab Sphere and attach BezierWalk.cs to them.
Spawn script:
public class Spawn : MonoBehaviour
{
public GameObject Sphere;
//string ScriptName = "BezierWalk";
void Start()
{
Vector3 vSpawnPos = transform.position;
for (int i = 0; i < 20; i++)
{
var objectYouCreate = Instantiate(Sphere, vSpawnPos, transform.rotation);
//objectYouCreate.AddComponent<T>("Assets/BezierWalk.cs");
//objectYouCreate.AddComponent(typeof(ScriptName)) as ScriptName;
//objectYouCreate.AddComponent<ScriptName>();
//var myScript = Sphere.AddComponent<BezierWalk.cs>();
vSpawnPos.z += 20;
}
}
You can see commented out attempts...
How I am supposed to do this properly? Thank you.
If you look at how you reference components in unity, the answer should be clear - did you try any of the ones you listed?
Reference: https://docs.unity3d.com/ScriptReference/GameObject.AddComponent.html
The normally used is as it is easy reading
objectYouCreate.AddComponent<ClassName>();
You can use
objectYouCreate.AddComponent(typeof(ClassName));
the .cs is for humans, its your readable version. so you would never need the .cs reference in your code.
note: I mentioned it as ClassName rather than scriptname, as while they are the same in monobehaviors in unity, it isnt the same anywhere else in c# so, the important bit is not the name of the file you made, but the name of the class within it.
Another way is to have prefabs, make a prefab of your object with all the components you need already on it.
If your script lies within certain namespace, you should follow the following format
GameObject.AddComponent(typeof(namespace.className));

Variables in other scripts in Unity

I am trying to create a game in Unity 2d. I have finished most of what I want to do and have moved on to the enemies. The enemies (dragons) come in from different points of screen. To do this I have placed sprite game objects where I want the dragon to spawn. I have made all of these objects a child of another object called DragonAncores. I attached a script to DragonAncores which says this...
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class DragonTracker : MonoBehaviour {
// is gold dragon in play?
public bool GoldDragonInit = false;
// curently active dragons
public int DragonCount = 0;
// defalts to 5
public int Difficulty = 5;
}
I am then attaching a script to each sprite which will eventually summon in a dragon Prefab (containing 2 colliders and an animator) biased of If statment logic derived from the other variables.
Below is the code I am using.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class Dragons : MonoBehaviour {
// same as GoldDragonInit
bool GoldDragonSpawn = false;
// same number as DragonCount in DragonTrackeer
int LiveDragons;
// same as Difficulty
int DifLev;
//get cariables from other script
DragonAncors.cs.GetComponent.<DragonTracker>() GoldDragonInit = GoldDragonSpawn;
System.Random RNG= new System.Random();
void update()
{
RSpawn=RNG.Next(0,2)
DragonType=RNG.Next(0,101)
if (RSpawn = 1) ;
{
if (LiveDragons > DifLev) ;
{
if (DragonType > 99) ;
{
// summon regular dragon
}
if (DragonType = 100) ;
{
if (GoldDragonSpawn = true) ;
{
// summon gold dragon
}
}
}
}
}
}
This is throwing up this error list.
This shows my hierarchy in unity and the anchor points (the Squair crosshair looking things)
I have looked for other threads that adress this topic and they all try different methods, none work.
I am using Unity 2018.2.18f1
There are a few errors in your code here. The following is incorrect.
//get cariables from other script
DragonAncors.cs.GetComponent.<DragonTracker>() GoldDragonInit = GoldDragonSpawn;
The correct way to access this, seeing as you said DragonAncors is the parent would be:
GetComponentInParent<DragonTracker>().GoldDragonInit = GoldDragonSpawn;
This sets the GoldDragonInit Boolean to the value of GoldDragonSpawn. This has to be inside a function, as you have it outside of a function I presume you needed this set on start. Therefore I have placed it in the void Start() function. This is called at the start of the game(loaded scene).
You also do not need semi-colons ; after an if statement, however it does need to appear after every line of difinitive code. The code you have provided should instead look like this.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class Dragons : MonoBehaviour {
// same as GoldDragonInit
bool GoldDragonSpawn = false;
// same number as DragonCount in DragonTrackeer
int LiveDragons;
// same as Difficulty
int DifLev;
void Start()
{
// variables from other script
GetComponentInParent<DragonTracker>().GoldDragonInit = GoldDragonSpawn;
}
System.Random RNG= new System.Random();
void update()
{
RSpawn=RNG.Next(0,2);
DragonType=RNG.Next(0,101);
if (RSpawn = 1)
{
if (LiveDragons > DifLev)
{
if (DragonType > 99)
{
// summon regular dragon
}
if (DragonType = 100)
{
if (GoldDragonSpawn = true)
{
// summon gold dragon
}
}
}
}
}
}
This works because DragonTracker is a script in the objects parent. If this was not the case then GetComponentInParent().GoldDragonInit = GoldDragonSpawn; would be replaced like so:
[SerializeField]
private GameObject DragonAncors;
void Start()
{
DragonAncors.GetComponent<DragonTracker>().GoldDragonInit = GoldDragonSpawn;
}
This is not valid c# code:
//get cariables from other script
DragonAncors.cs.GetComponent.<DragonTracker>() GoldDragonInit = GoldDragonSpawn;
Why? Because it isn't inside a method.
Also, the comment is wrong. It isn't getting a variable (typo, too), its setting a variable in another script!
The reason for the first...16 problems Visual Studio is complaining about are because of this line.
At this location you are only allowed to declare methods, fields, and properties and you're currently trying to access another class and change one of its members (something you can only do inside a method).
Additionally, you have .cs which I assume is because "DragonAnchors.cs is the file name!" which you don't need to do. I'm not sure how to go about rewriting this line (inside Start()) as I'm not sure what you're trying to actually do. That is, I don't know where an instance of DragonAnchors actually resides. You're calling GetComponent(), which is typically reserved for accessing components attached to game objects, but as you've attempted to do so on a static class reference, I'm not sure if you meant to call it on this or on something else.
This is how you can get to DragonTracker:
DragonTracker dt = GameObject.Find("DragonAncores").GetComponent<DragonTracker>()
Debug.Log(dt.DragonCount);
There are a lot of errors there and they may take some steps to go through, but first things first you should clear up the issue with the code you're trying to use being unsupported. Go into the project settings and change the compiler language version as it notes on the 5th error down. This should allow you to use the newer functionality.

Using foreach loop to find GameObjects that are children of something else (Unity3d)

I am making a video game, and while I have an existing code in generic C#, I now have to move it to Unity. I have some basic knowledge with generic C#, but I just started to learn the Unity way of coding.
For starters, I want to write a code that positions all game areas to correct positions, then turn them invisible. Yes, don't be surprised, they need to be all in same places.
Areas can have three size options, I called them Small, Medium and Large. Small and large areas have to be written manually.
List <GameObject> SmallAreas = new List<GameObject>();
void DefineSmallAreas()
{
SmallAreas.Add(areaConfirmLoad);
SmallAreas.Add(areaConfirmQuit);
SmallAreas.Add(areaConfirmSave);
SmallAreas.Add(areaGameSaved);
SmallAreas.Add(areaSave);
SmallAreas.Add(areaLoad);
}
Same with large areas.
Now, all other areas, are medium, and there is a large number of them.
So, I want to go through all game objects that are children of "areaContainer", check if their names start with "area", and if they do, I want to add them to MediumAreas list.
That's how I tried it:
void DefineMediumAreas()
{
GameObject areaContainer = GameObject.Find("areaContainer");
foreach (GameObject thisObject in areaContainer)
{
char[] a = thisObject.Name.ToCharArray();
if (a.Length >= 4)
{
char[] b = { a[0], a[1], a[2], a[3] };
string thisObjectType = new string(b);
(if (thisObjectType == "area")&&(!(SmallAreas.Contains(thisObject))
&&(!(LargeAreas.Contains(thisObject)))
{
MediumAreas.Add(thisObject);
}
}
}
This however shows an error, that "areaContainer" can't be used that way, I don't have access to Unity now, so can't copy exact message. I think that it's something like "Gameobject doesn't have IEnumerator".
I did try to google for the better approach, and found something called "transform".
foreach(Transform child in transform)
{
Something(child.gameObject);
}
What I don't understand, is how to use this "transform" in my specific situation.
Please don't get angry at me if this question is silly, I am very new to Unity, and have to learn it from scratch.
And a small second question. Will this work of turning object invisible work:
foreach(GameObject thisObject in MediumAreas)
{
thisObject.position = MediumVector;
thisObject.GetComponent<Renderer>().enabled = false;
}
MediumVector is location where the object must be moved to, and it seems to be working.
You can do this: foreach(Transform child in transform)
because the Transform class implements IEnumerable and have some mechanism that enables you to access the child GameObjects with the foreach loop.
Unfortunately, you can't do this: foreach (GameObject thisObject in areaContainer)
because areaContainer is a GameObject and this implementation is not done for the GameObject class. That's why you are getting this error:
foreach statement cannot operate on variables of type
'UnityEngine.GameObject' because 'UnityEngine.GameObject' does not
contain a public definition for 'GetEnumerator'
To fix it, change your loop to use Transform after finding the GameObject:
GameObject areaContainer = GameObject.Find("areaContainer");
foreach (Transform thisObject in areaContainer.transform){}
The complete code:
List<GameObject> MediumAreas = new List<GameObject>();
void DefineMediumAreas()
{
GameObject areaContainer = GameObject.Find("areaContainer");
foreach (Transform thisObject in areaContainer.transform)
{
//Check if it contains area
if (thisObject.name.StartsWith("area"))
{
//Add to MediumAreas List
MediumAreas.Add(thisObject.gameObject);
}
}
}
There is multiple approaches to your problem. One of them is using Tags. Simply mark your MediumArea prefab with some Tag and then you can find all tagged GameObjects with FindGameObjectsWithTag(string) (Unity Docs). Then you can populate your collection like that:
MediumAreas.AddRange(FindGameObjectsWithTag("MediumArea"));
Second approach could be finding all objects with same attached script FindObjectsOfType<T>() (Unity Docs). This is usefull when you are searching for instances of same type, like Medium Area.
Lets say that you have an Area script
public class Area : MonoBehaviour {
public AreaSize Size; // AreaSize is Enum
}
Then you can simply find your areas like:
var allAreas = FindGameObjectsOfType<Area>();
var mediumAreas = allAreas.Where(e => e.Size == AreaSize.Medium); // using System.Linq;
I created a project to answer your question, the final result will be like this :
As you can see I have created a game object called "areaContainer" and added 3 children with respective names : "area01", "area02" and "anotherObject".
The script that manage to get all "areaContainer" children that start with "area" looks like :
public GameObject areaContainer;
public List<GameObject> MediumAreas = new List<GameObject>();
private void Start()
{
DefineMediumAreas();
}
void DefineMediumAreas()
{
for (int i = 0; i < areaContainer.transform.childCount; i++)
{
var childGameObject = areaContainer.transform.GetChild(i).gameObject;
if (childGameObject.name.StartsWith("area"))
MediumAreas.Add(childGameObject);
}
}
1- I ended up referencing the areaContainer object in a script rather than using GameObject.Find because it's more performant.
2- To get a child of a game object you need to access to its transform and call GetChild(index). So by iterating through the parent container which is "areaContainer" we are getting its childCount.
3- To check if the name start with "area", simply use .StartsWith("area") which return true or false.
For your second question, you can hide object disabling the Renderer or by deactivating it (thisObject.SetActive(false);
I hope this help you; Happy coding!
You want to access all game objects that are children of "areaContainer"
In void DefineMediumAreas() function, you need to Transform[] to get an array of childeren. Use this:
Transform[] areaContainer = GameObject.Find("areaContainer").GetComponentsInChildren<Transform>();
foreach(Transform thisTransform in areaContainer)
{
...
}
I hope it helps you

Enabling Game objects

So I've been trying to access game objects in my scene (which are disabled), to enable them. But I'm getting an error: "Object reference not set to an instance of an object"
private List<Character> characters = new List<Character>();
private List<GameObject> characterGameObjects = new List<GameObject> ();
public void loadSceneCharacters(){
if (characters != null) {
for(int i = 0; i < characters.Count; i++){
characterGameObjects.Add(GameObject.Find(characters[i].CharacterName));
characterGameObjects[i].SetActive(true);
}
}
}
You can't find disabled gameobjects.
A solution is to either reference them in inspector or find them all first when they are enabled, then disable those you don't need.
I think your characters list is empty.
If you don't Instantiate GameObjects you can fill characters list with drag and drop so you can change code like this.
public List<Character> characters = new List<Character>(); ///Thanks to public
//you can see list in Unity Editor
private List<GameObject> characterGameObjects = new List<GameObject> ();
public void loadSceneCharacters(){
if (characters != null) {
for(int i = 0; i < characters.Count; i++){
characterGameObjects.Add(characters[i])); //get and add gameobject
characterGameObjects[i].SetActive(true);
}
}
}
If you have dynamically created GameObjects you can fill the list with GameObject.Find("CharacterName");
However, i dont suggest that find every gameobject with name.Instead of that, During the Instantiate state you can add new gameObject instance to your character list.
Even if the character list would be empty this code would not throw an exception.
The problem is probably that you can not find disabled gameobject using the find methods (at least that was my experience, correct me if i am wrong guys).
What i usually do as a workaround instead of searching is to add the gameobjects via drag and drop. If this is not possible you can either, search for the gameobjects in Awake or Start, add them to your list and disable them. Or do some sort of adding when you instanciate them... Basicly you have to somehow get the reference to the gameobjects before you disable them.
Hope this helps.
Something that can help you is to create an empty object, then put all your characters inside the empty object.. then by code do something like:
foreach(Character c in MyEmptyObject.GetComponentsInChildren(Character, true))//the true in this
//line indicates that it should search for inactive objects
{
c.gameObject.SetActive(true);
}
this assuming that your characters have an script called "Character"

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