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Unity - Cant access reference to another script

I am trying to learn how does Unity work and I now struggle with problem that I cannot access script from another script. I was searching on Interner for couple hours, I have tried many options but nothing helped.
I have 2 scripts.
CoinSpawn.cs - attached to Player (I would change it to other object but I dont know yet to which one, because its something that runs in background so it really dont need to be on player)
CollectingCoin.cs - attached to Coin (Coin is object, that its not on game scene on the start, it spawns randomly)
CoinSpawn is script that randomly spawn Instantiate of object Coin. I want to change value of CoinSpawn.currentCoinOnScreen from CollectingCoin. I ve tried
CoinSpawn test = GameObject.Find("CoinSpawn").GetComponent<CoinSpawn>();
and it doesnt work. I also have my both scripts in the same asset folder. What am I doing wrong? Thank you
CoinSpawn.cs
public class CoinSpawn : MonoBehaviour
{
public GameObject coin;
public int maximumCoinPerScreen = 10;
public int currentCoinOnScreen = 0;
private int randomNumber;
private Vector2 spawnPosition;
private void Update()
{
randomNumber = Random.Range(1, 1000);
if(randomNumber >= 0 && randomNumber <= 1 && currentCoinOnScreen != maximumCoinPerScreen)
{
currentCoinOnScreen++;
float spawnY = Random.Range
(Camera.main.ScreenToWorldPoint(new Vector2(0, 0)).y, Camera.main.ScreenToWorldPoint(new Vector2(0, Screen.height)).y);
float spawnX = Random.Range
(Camera.main.ScreenToWorldPoint(new Vector2(0, 0)).x, Camera.main.ScreenToWorldPoint(new Vector2(Screen.width, 0)).x);
spawnPosition = new Vector2(spawnX, spawnY);
GameObject coinObject = Instantiate(coin, spawnPosition, Quaternion.identity);
}
}
}
CollectingCoin.cs
public class CollectingCoin : MonoBehaviour
{
UnityEngine.UI.Text Coins;
public static int totalCoins = 0;
private void Start()
{
Coins = GameObject.Find("Score").GetComponent<UnityEngine.UI.Text>();
}
void OnTriggerEnter2D(Collider2D c2d)
{
if (c2d.CompareTag("Player"))
{
totalCoins++;
Destroy(gameObject);
Coins.text = "COINS: " + totalCoins.ToString();
// TESTING
CoinSpawn test = GameObject.Find("CoinSpawn").GetComponent<CoinSpawn>();
CoinSpawn test2 = GetComponent<CoinSpawn>();
}
}
}

GameObject.Find("CoinSpawn").GetComponent<CoinSpawn>();
Searches for a GameObject with the name CoinSpawn. Since you told us this component is rather attached to the player object it makes sense that it isn't found.
GetComponent<CoinSpawn>();
searches for a CoinSpawn component on the very same object your CollectingCoin is attached to. From your description this clearly also isn't the case.
Since you say the CoinSpawn is attached to the player then you probably rather want to get the component from
void OnTriggerEnter2D(Collider2D c2d)
{
if (c2d.CompareTag("Player"))
{
...
// rather get the component on the player object you collided with
CoinSpawn test = c2d.GetComponent<CoinSpawn>();
}
}
Alternatively assuming there is only one single instance of CoinSpawn in your scene anyway and not necessarily on your player you could use FindObjectOfType
CoinSpawn test = FindObjectOfType<CoinSpawn>();

First of all, Do not ever use GameObject.Find(), its very expensive as it will go through all game objects in your scene to find the object. and this not a performance wise.
There are many ways to do so.
Easyest one:
Add both script to same gameobject as component.
Make a global variable CoinSpawn inside CollectingCoin script and then use [serializedFiled] tag on top of it, by this way, you can drag and drop the reference in the editor before you start play. and you can access it the way you want.
2nd way:
Is same as first one, but instead of serializedFiled, just cache it at the beginning by using GetComponent.
Just make sure you have both scripts attached to the same gameobject.
public class CollectingCoin : MonoBehaviour
{
UnityEngine.UI.Text Coins;
public static int totalCoins = 0;
CoinSpawn coinSpawn;
private void Start()
{
coinSpawn = GetComponent<CoinSpawn>();
Coins = GameObject.Find("Score").GetComponent<UnityEngine.UI.Text>();
}
void OnTriggerEnter2D(Collider2D c2d)
{
if (c2d.CompareTag("Player"))
{
totalCoins++;
Destroy(gameObject);
Coins.text = "COINS: " + totalCoins.ToString();
// DO Whaterver you want with coinSpawn here
}
}
}

interconnecting scripts in unity3D using the preprocessor [duplicate]

I've searched around and I just can't get this to work. I think I just don't know the proper syntax, or just doesn't quite grasp the context.
I have a BombDrop script that holds a public int. I got this to work with public static, but Someone said that that is a really bad programming habit and that I should learn encapsulation. Here is what I wrote:
BombDrop script:
<!-- language: c# -->
public class BombDrop : MonoBehaviour {
public GameObject BombPrefab;
//Bombs that the player can drop
public int maxBombs = 1;
// Update is called once per frame
void Update () {
if (Input.GetKeyDown(KeyCode.Space)){
if(maxBombs > 0){
DropBomb();
//telling in console current bombs
Debug.Log("maxBombs = " + maxBombs);
}
}
}
void DropBomb(){
// remove one bomb from the current maxBombs
maxBombs -= 1;
// spawn bomb prefab
Vector2 pos = transform.position;
pos.x = Mathf.Round(pos.x);
pos.y = Mathf.Round(pos.y);
Instantiate(BombPrefab, pos, Quaternion.identity);
}
}
So I want the Bomb script that's attached to the prefabgameobject Bombprefab to access the maxBombs integer in BombDrop, so that when the bomb is destroyed it adds + one to maxBombs in BombDrop.
And this is the Bomb script that needs the reference.
public class Bomb : MonoBehaviour {
// Time after which the bomb explodes
float time = 3.0f;
// Explosion Prefab
public GameObject explosion;
BoxCollider2D collider;
private BombDrop BombDropScript;
void Awake (){
BombDropScript = GetComponent<BombDrop> ();
}
void Start () {
collider = gameObject.GetComponent<BoxCollider2D> ();
// Call the Explode function after a few seconds
Invoke("Explode", time);
}
void OnTriggerExit2D(Collider2D other){
collider.isTrigger = false;
}
void Explode() {
// Remove Bomb from game
Destroy(gameObject);
// When bomb is destroyed add 1 to the max
// number of bombs you can drop simultaneously .
BombDropScript.maxBombs += 1;
// Spawn Explosion
Instantiate(explosion,
transform.position,
Quaternion.identity);
In the documentation it says that it should be something like
BombDropScript = otherGameObject.GetComponent<BombDrop>();
But that doesn't work. Maybe I just don't understand the syntax here. Is it suppose to say otherGameObject? Cause that doesn't do anything. I still get the error : "Object reference not set do an instance of an object" on my BombDropScript.maxBombs down in the explode()

You need to find the GameObject that contains the script Component that you plan to get a reference to. Make sure the GameObject is already in the scene, or Find will return null.
GameObject g = GameObject.Find("GameObject Name");
Then you can grab the script:
BombDrop bScript = g.GetComponent<BombDrop>();
Then you can access the variables and functions of the Script.
bScript.foo();
I just realized that I answered a very similar question the other day, check here:
Don't know how to get enemy's health
I'll expand a bit on your question since I already answered it.
What your code is doing is saying "Look within my GameObject for a BombDropScript, most of the time the script won't be attached to the same GameObject.
Also use a setter and getter for maxBombs.
public class BombDrop : MonoBehaviour
{
public void setMaxBombs(int amount)
{
maxBombs += amount;
}
public int getMaxBombs()
{
return maxBombs;
}
}

use it in start instead of awake and dont use Destroy(gameObject); you are destroying your game Object then you want something from it
void Start () {
BombDropScript =gameObject.GetComponent<BombDrop> ();
collider = gameObject.GetComponent<BoxCollider2D> ();
// Call the Explode function after a few seconds
Invoke("Explode", time);
}
void Explode() {
//..
//..
//at last
Destroy(gameObject);
}
if you want to access a script in another gameObject you should assign the game object via inspector and access it like that
public gameObject another;
void Start () {
BombDropScript =another.GetComponent<BombDrop> ();
}

Can Use this :
entBombDropScript.maxBombs += 1;
Before :
Destroy(gameObject);
I just want to say that you can increase the maxBombs value before Destroying the game object. it is necessary because, if you destroy game object first and then increases the value so at that time the reference of your script BombDropScript will be gone and you can not modify the value's in it.

Accessing a variable from another script C# UNITY [duplicate]

This question already has answers here:
How to access a variable from another script in another gameobject through GetComponent?
(3 answers)
Closed 6 years ago.
I have two script
simplecloudhander.cs
cloudtarget.cs
simplecloudhander.cs
public string mTargetMetadata = "";
public void OnNewSearchResult(TargetFinder.TargetSearchResult targetSearchResult)
{
GameObject newImageTarget = Instantiate(ImageTargetTemplate.gameObject) as GameObject;
GameObject augmentation = null;
string model_name = targetSearchResult.MetaData;
if( augmentation != null )
augmentation.transform.parent = newImageTarget.transform;
ImageTargetAbstractBehaviour imageTargetBehaviour = mImageTracker.TargetFinder.EnableTracking(targetSearchResult, newImageTarget);
Debug.Log("Metadata value is " + model_name );
mTargetMetadata = model_name;
}
i want to access mTargetMetadata value in another cloudtarget.cs script
here cloudtarget.cs script
void OnGUI() {
SimpleCloudHandler sc = new SimpleCloudHandler ();
GUI.Label (new Rect(100,300,300,50), "Metadata: " + sc.mTargetMetadata);
}
but i can't get mTargetMetadata value in another script

You have to add a reference to that script in the cloudtarget script. Just add a public variable of type SimpleCloudHandler to the class cloudtarget, not on the OnGUI method, later drag and drop the GameObject with the SimpleCloudHandler atached to the script cloudtarget in the inspector.
Example:
Drag and drop the MainCamera with the SimpleCloudHandler script attached => to the public SimpleCloudHandler variable of the cloudtarget script through the inspector.
There are multiple ways to make a reference in Unity, I recommend you to look to the documentation that Unity offer

if your scripts are attached to the same object then you can use GetComponentlike this,
gameObject.GetComponent<simplecloudhander>().mTargetMetadata
if they are not attached to the same gameObjectthe you can use GameObject.Find first to find the gameObject that the script is attached to, you should use the name of the gameObject to find it, then use the GetComponent to get the componentthat you want
GameObject.Find("nameOftheGameObject").GetComponent<simplecloudhander>().mTargetMetadata
also there is no need for new keyword, if you just want to access it,
simplecloudhander sch;
void Start()
{
sch = GameObject.Find("nameOftheGameObject").GetComponent<simplecloudhander>();
}
void OnGUI() {
GUI.Label (new Rect(100,300,300,50), "Metadata: " + sch .mTargetMetadata);
}

Unity 4.6 Editor, Create a Script with Predefined Data

I am trying to make an easy to use button inside the Unity Editor for Character and Item creation.
I will throw out a little extra info here to help explain my issue.
My game is structured like this;
Game Controller >> Character Script >> (PlayerName)Script
A character object has both the character script and a script named after it, on it.
I want to be able to click "Create New Character" in the Unity editor and it do the following;
1) Prompt for a Name to use.
2) Create Empty Game Object named Name from whatever the user typed in.
3) Create a new C# Script named the same, and add it to the object.
-I want the generated script to have some pre-determined "Character Template" code in it.
4) Attach the new Script to the new empty game object, and attach a "Character Script" to it as well.
Thanks in advance.
One last sub-question.
Would it be better to Access the PlayerNamedScript from the GameController by a public monobehaviour on the Character Script?
Or can the CharacterScript Dynamically extend the PlayerNamedScript, sibling.
I hope that is clear. Thanks again.

Try this out
Put the CharacterCreatorEditor.cs in a folder named Editor somewhere in your project.
CharacterCreatorEditor.cs
using UnityEngine;
using System.Collections;
using UnityEditor;
using System.IO;
using System.Text.RegularExpressions;
public class CharacterCreatorEditor : EditorWindow {
#region Character Fields
//Add as many character specific fields / variables you want here.
//Remember to update the same thing in the "CharacterTemplate.txt"!
public string characterName = "John Doe";
public float characterHealth = 10;
public int characterCost = 1000;
public bool isBadGuy = false;
#endregion
private bool needToAttach = false; //A boolean that checks whether a newly created script has to be attached
private float waitForCompile = 1; //Counter for compile
GameObject tempCharacter; //A temporary GameObject that we assign the new chracter to.
//A Menu Item when clicked will bring up the Editor Window
[MenuItem ("AxS/Create New Character")]
public static void CreateNewChar () {
EditorWindow.GetWindow(typeof(CharacterCreatorEditor));
}
void OnGUI () {
GUILayout.Label("Here's a sample Editor Window. Put in more variables as you need below.");
GUILayout.Space(10);
//Note on adding more fields
//The code below is broken into groups, one group per variable
//While it's relatively long, it keeps the Editor Window clean
//Most of the code should be fairly obvious
GUILayout.BeginHorizontal();
GUILayout.Label("Character Name", new GUILayoutOption[0]);
characterName = EditorGUILayout.TextField(characterName, new GUILayoutOption[0]);
GUILayout.EndHorizontal();
GUILayout.Space(10);
GUILayout.BeginHorizontal();
GUILayout.Label("Character Health", new GUILayoutOption[0]);
characterHealth = EditorGUILayout.FloatField(characterHealth, new GUILayoutOption[0]);
GUILayout.EndHorizontal();
GUILayout.Space(10);
GUILayout.BeginHorizontal();
GUILayout.Label("Character Cost", new GUILayoutOption[0]);
characterCost = EditorGUILayout.IntField(characterCost, new GUILayoutOption[0]);
GUILayout.EndHorizontal();
GUILayout.Space(10);
GUILayout.BeginHorizontal();
GUILayout.Label(string.Format("Is {0} a Bad Guy?", new object[] { characterName }), new GUILayoutOption[0]);
isBadGuy = EditorGUILayout.Toggle(isBadGuy, new GUILayoutOption[0]);
GUILayout.EndHorizontal();
GUILayout.Space(10);
GUI.color = Color.green;
//If we click on the "Done!" button, let's create a new character
if(GUILayout.Button("Done!", new GUILayoutOption[0]))
CreateANewCharacter();
}
void Update () {
//We created a new script below (See the last few lines of CreateANewCharacter() )
if(needToAttach) {
//Some counter we just keep reducing, so we can give the
//EditorApplication.isCompiling to kick in
waitForCompile -= 0.01f;
//So a few frames later, we can assume that the Editor has enough
//time to "catch up" and EditorApplication.isCompiling will now be true
//so, we wait for the newly created script to compile
if(waitForCompile <= 0) {
//The newly created script is done compiling
if(!EditorApplication.isCompiling) {
//Lets add the script
//Here we add the script using the name as a string rather than
//it's type in Angled braces (As done below)
tempCharacter.AddComponent(characterName.Replace(" ", ""));
//Reset the control variables for attaching these scripts.
needToAttach = false;
waitForCompile = 1;
}
}
}
}
private void CreateANewCharacter () {
//Instantiate a new GameObject
tempCharacter = new GameObject();
//Name it the same as the Character Name
tempCharacter.name = characterName;
//Add the ChracterScript component. Note the use of angle braces over quotes
tempCharacter.AddComponent<CharacterScript>();
//Loading the template text file which has some code already in it.
//Note that the text file is stored in the path PROJECT_NAME/Assets/CharacterTemplate.txt
TextAsset templateTextFile = AssetDatabase.LoadAssetAtPath("Assets/CharacterTemplate.txt",
typeof(TextAsset)) as TextAsset;
string contents = "";
//If the text file is available, lets get the text in it
//And start replacing the place holder data in it with the
//options we created in the editor window
if(templateTextFile != null) {
contents = templateTextFile.text;
contents = contents.Replace("CHARACTERCLASS_NAME_HERE", characterName.Replace(" ", ""));
contents = contents.Replace("CHARACTER_NAME_HERE", characterName);
contents = contents.Replace("CHARACTER_HEALTH_HERE", characterHealth.ToString());
contents = contents.Replace("CHARACTER_COST_HERE", characterCost.ToString());
contents = contents.Replace("CHARACTER_BAD_GUY_HERE", isBadGuy.ToString().ToLower());
}
else {
Debug.LogError("Can't find the CharacterTemplate.txt file! Is it at the path YOUR_PROJECT/Assets/CharacterTemplate.txt?");
}
//Let's create a new Script named "CHARACTERNAME.cs"
using(StreamWriter sw = new StreamWriter(string.Format(Application.dataPath + "/{0}.cs",
new object[] { characterName.Replace(" ", "") }))) {
sw.Write(contents);
}
//Refresh the Asset Database
AssetDatabase.Refresh();
//Now we need to attach the newly created script
//We can use EditorApplication.isCompiling, but it doesn't seem to kick in
//after a few frames after creating the script. So, I've created a roundabout way
//to do so. Please see the Update function
needToAttach = true;
}
}
Put the below text file into the path "YOUR_PROJECT/Assets/CharacterTemplate.txt" If you don't, the code WON'T WORK!
CharacterTemplate.txt
using UnityEngine;
using System.Collections;
public class CHARACTERCLASS_NAME_HERE : MonoBehaviour {
public string characterName = "CHARACTER_NAME_HERE";
public float characterHealth = CHARACTER_HEALTH_HERE;
public int characterCost = CHARACTER_COST_HERE;
public bool isBadGuy = CHARACTER_BAD_GUY_HERE;
public void SomeMethod () {
}
}
Explanation of the code
First, the editor script takes all the input variables (should be fairly obvious what they are)
Once you click the done button, the following happen
A new GameObject is Instantiated
The instantiated GameObject is named the same as the Character Name in the Editor (eg. John Doe)
The CharacterScript (your common script) is attached
The template text file ("CharacterTemplate.txt") is read, and all the data is replaced with the data you entered in the Editor Window
This is then written to a new script file
We refresh the Asset Database, and wait until the newly created script is compiled (eg. JohnDoe.cs)
Lastly attach the script to the GameObject instantiated in Step 1
For your second question, what you'll need to do is to have all your PlayerNamedClass extend the same base class. This way, you can type the variable you'll expose in CharacterScript
So, for example, if you call the base class "NamedCharacterScripts"
In JohnDoe.cs
public class JohnDoe : NamedCharacterScripts
In JaneDoe.cs
public class JaneDoe : NamedCharacterScripts
In CharacterScript.cs
public NamedCharacterScripts namedCharacterScript;
void Awake () {
//This will assign JohnDoe.cs for the GameObject named "John Doe" &
//JaneDoe.cs to the GameObject named "Jane Doe"
namedCharacterScript = GetComponent<NamedCharacterScripts>();
}
Hope this answers your questions. If you have trouble, just leave a comment

My script is not production-ready like Venkat's answer, but it should be easier to understand for educational purposes.
using UnityEngine;
using System.Collections;
using UnityEditor;
using System.IO;
[ExecuteInEditMode]
public class CharacterTools : MonoBehaviour
{
[SerializeField, HideInInspector]
private string className;
private bool waitForCompile = false;
private void Update()
{
if (string.IsNullOrEmpty(className))
return;
if (waitForCompile && EditorApplication.isCompiling)
waitForCompile = false;
if (!waitForCompile && !EditorApplication.isCompiling)
{
var gameObject = new GameObject(className);
Debug.Log("Attempting to add " + className);
var c = gameObject.AddComponent(className);
className = null;
}
}
[ContextMenu("Create character")]
private void CreateCharacter()
{
string name = "Number" + Random.Range(0, 100).ToString();
string nameTemplate = "{0}Character";
string contentTemplate = #"using UnityEngine;
public class {0} : MonoBehaviour
{{
}}
";
var className = string.Format(nameTemplate, name);
var path = Application.dataPath + "/" + className + ".cs";
var scriptFile = new StreamWriter(path);
scriptFile.Write(string.Format(contentTemplate, className));
scriptFile.Close();
AssetDatabase.ImportAsset(path, ImportAssetOptions.ForceSynchronousImport);
AssetDatabase.Refresh();
this.className = className;
this.waitForCompile = true;
}
}
Usage:
Add this script to any object on scene.
Right click on just added component in inspector.
Choose “Create character”.
Wait few seconds.

Changing sprite frame on mouseEnter in Unity [duplicate]

This question already has answers here:
What is a NullReferenceException, and how do I fix it?
(27 answers)
Closed 8 years ago.
I have an assets file under the name of play-button with texture type=sprite2D and Sprite Mode = Multiple, it contains 2 different frames: play-button0 and play-button1
i have attached a c# script file for this asset with the following code:
using UnityEngine;
using System.Collections;
public class Play_btn : MonoBehaviour {
SpriteRenderer spriteRenderer;
Sprite s1;
Sprite s2;
// Use this for initialization
void Start () {
spriteRenderer = GetComponent<SpriteRenderer>();
if (spriteRenderer.sprite == null)
spriteRenderer.sprite = s1;
}
void OnMouseDown() {
Application.LoadLevel("Levels");
}
void OnMouseEnter() {
spriteRenderer.sprite = s2;
}
void OnMouseExit() {
//spriteRenderer.sprite = sprite1;
}
// Update is called once per frame
void Update () {
}
}
As you can see i am trying to change the frame onMouseEnter and OnMouseExit but when the mouseEnter the play button a null reference error is occurring and a blank object is displaying on the screen, can anyone help me in this problem?

From what I see, the Sprites s1 & s2 are not public (so you could not have assigned it via the inspector), and there's no code where you assign the s1 & s2 variables.
Solution
Make the Sprites s1 and s2 public, and assign them.