Why is transform.parent null in Awake() and Start()? - c#

I'm trying to get a reference to the GameObject that the script is attached to. Per docs transform.parent.gameObject is used for this but transform.parent is null in both Awake() and Start(). What do I need to do to get this working? This is probably a total noob question but Google didn't come up with a working answer so far.
using UnityEngine;
using System.Collections;
public class Test : MonoBehaviour
{
private void Awake()
{
var obj = transform.parent;
Debug.Log(obj);
}
private void Start()
{
var obj = transform.parent;
Debug.Log(obj);
}
}

Nevermind! I'm an idiot! It shouldn't be parent but:
var obj = transform or var obj = transform.gameObject
since this script is part of the game object which it should refer to, not any parent. I had the strange assumption that a script is a child of a game object.

Transform.parent tells you what the parent of your current transform is. I.E. if GameObjectA is a child of GameObjectB, a script that accesses transform.gameObject in GameObjectB will return GameObjectA
What you're looking for, in fact, is just gameObject. This implicitly returns the gameObject your script is attached to.
Create two GameObjects in your scene.
Call one GameObjectA, and the other GameObjectB.
Attach this script to GameObjectB and then drag GameObjectB to be under GameObjectA in the hierarchy
public class ExampleBehaviour : MonoBehaviour {
void Awake () {
Debug.Log(gameObject.name); //Prints "GameObjectB" to the console
Debug.Log(transform.parent.name); //Prints "GameObjectA" to the console
}
}

Related

Finding a way for script to detect a child in a playerContainer game object

I'm currently making a 3D endless runner game with the choice to select different skins for the player. Everything's going smoothly until I come across a problem, in which I try to assign two collision game objects to each character prefab in the container that can detect the player's collision box when it collides with a powerup.
It only detects the first playerContainer's (Milo) 'Coin Detect' game object (eventhough it's been deactivated) and does not recognize the 'Coin Detect' collision game object in the Baddie playerContainer (which the player has chosen to play)
So my question is, how am I able to get the script to recognize the child that's active in the third playerContainer game object instead of it automatically detecting the first playerContainer game object's child?
From the Magnet powerup script I've made, the script detects the first playerContainer's 'Coin Detect' game object only. As shown in the attached picture below:
Here's my current script where the player is able to select their preferred characters.
using System.Collections.Generic;
using UnityEngine;
public class EnablePlayerSelector : MonoBehaviour
{
public GameObject[] players;
public int currPlayerCount;
void Start()
{
currPlayerCount = PlayerPrefs.GetInt("SelectedPlayer", 0);
foreach (GameObject player in players)
player.SetActive(false);
players[currPlayerCount].SetActive(true);
}
}
and here's the script where I deactivate the 'Coin Detect' collision game Object and activate it when the player collides with the powerup.
using System.Collections.Generic;
using UnityEngine;
public class Magnet : MonoBehaviour
{
public GameObject coinDetect;
void Start()
{
coinDetect = GameObject.FindGameObjectWithTag("CoinDetect");
coinDetect.SetActive(false);
Debug.Log("False");
}
private void OnTriggerEnter(Collider other)
{
if(other.gameObject.tag == "Player")
{
StartCoroutine(coinActivate());
Destroy(transform.GetChild(0).gameObject);
}
}
IEnumerator coinActivate()
{
Debug.Log("Hi");
coinDetect.SetActive(true);
yield return new WaitForSeconds(5f);
coinDetect.SetActive(false);
}
}
Well your issue is rather that you are doing GameObject.FindGameObjectWithTag("CoinDetect") which will return whatever is the first encountered CoinDetect in your scene in this moment. So unless EnablePlayerSelector.Start is executed before the Magnet.Start it will always be the first one since they are still all active by then.
You could probably already solve your issue by following the general thumb-rule:
Do things where you do not depend on other components already in Awake
Do things where you o depend on other components in Start
This way you already cover most of the use cases and are sure that components are self-initialized (Awake) before anything is accessing them in Start.
So simply change the EnablePlayerSelector.Start into Awake and you should be fine.
In very specific cases you might still have to adjust the Script Execution Order or use events.
Instead of doing this at all though I would rather in the moment of the collision request the current one from the PlayerContainer directly:
// put this on each player root object
public class Player : MonoBehaviour
{
// reference these via the Inspector
[SerializeField] private GameObject coinDetector;
[SerializeField] private GameObject playerrange;
// ... and in general any information bout this Player that is relevant for other scripts
// Readonly accessor property
public GameObject CoinDetector => coinDetector;
}
and then rather have
public class EnablePlayerSelector : MonoBehaviour
{
[SerializeField] private Player[] players;
[SerializeField] private int currPlayerCount;
public Player CurrentPlayer => players[currPlayerCount];
// In general do things where you don't depend on other scripts already in Awake
// This way you could actually already solve your issue by keeping things where you do
// depend on others in Start
private void Awake()
{
currPlayerCount = PlayerPrefs.GetInt("SelectedPlayer", 0);
for(var i = 0; i < players.Length; i++)
{
players[i].gameObject.SetActive(i == currPlayerCount);
}
}
}
and then finally do e.g.
public class Magnet : MonoBehaviour
{
public float effectDuration = 5f;
private IEnumerator OnTriggerEnter(Collider other)
{
var playerSelector = other.GetComponentInParent<EnablePlayerSelector>();
if(!playerSelector) yield break;
Debug.Log("Hi");
Destroy(transform.GetChild(0).gameObject);
var coinDetect = playerSelector.CurrentPlayer.CoinDetector;
coinDetect.SetActive(true);
yield return new WaitForSeconds(effectDuration);
coinDetect.SetActive(false);
}
}
or alternatively if the other in this case refers to the object with the Player component anyway you could also directly do
public class Magnet : MonoBehaviour
{
public float effectDuration = 5f;
private IEnumerator OnTriggerEnter(Collider other)
{
if(!other.TryGetComponent<Player>(out var player)) yield break;
Debug.Log("Hi");
Destroy(transform.GetChild(0).gameObject);
var coinDetect = player.CoinDetector;
coinDetect.SetActive(true);
yield return new WaitForSeconds(effectDuration);
coinDetect.SetActive(false);
}
}

How to access the value of cinemachine's camera distance in Unity / C#?

I'm working on Unity/C# now and I'm stuck with accessing CinemachineVirtualCamera's camera distance value in the script. What I'm trying to do is change the value of camera distance in the body section.
First of all, how can I access the CinemachineVirtualCamera component in this game object? The MoveScript is what I attached to a player game object, and I want to zoom out the camera depending on the player's movement. Since the game I'm making is small, I won't make other .cs files.
I wrote
public class MoveScript: MonoBehaviour
{
private GameObject camObj;
void Start()
{
camObj = GameObject.Find("Vertical Follow Camera");
camObj.GetComponent<CinemachineVirtualCamera>(); // <- but I get error saying, The type or namespace name 'CinemachineVirtualCamera' could not be found
}
}
I also read this document and I think the m_CameraDistance is what I'm looking for but how can I access that value?
For anyone else who wondering
GetComponent<CinemachineVirtualCamera>()
.GetCinemachineComponent<CinemachineFramingTransposer>()
.m_CameraDistance
As stated in the linked document, these classes are in Cinemachine namespace. To access the classes you have to either add
using Cinemachine;
to the beginning of your script or change your script to
public class MoveScript: MonoBehaviour
{
private GameObject camObj;
void Start()
{
camObj = GameObject.Find("Vertical Follow Camera");
camObj.GetComponent<Cinemachine.CinemachineVirtualCamera>();
}
}
And as for accessing the m_CameraDistance variable, HuySora already answered that part
Try this and don't forgot to mention namespace
public class MoveScript: MonoBehaviour
{
private CinemachineVirtualCamera virtualCamera;
private GameObject camObj;
void Start()
{
camObj = GameObject.Find("Vertical Follow Camera");
virtualCamera = camObj.GetComponent<CinemachineVirtualCamera>();
float f = virtualCamera.m_CameraDistance;
}
}

Assign gameObject of a script via another script?

How do I assign a gameObject of one script through another script's gameObject? For example;
Script_1
public class Script_1 : MonoBehaviour
{
public OVRScript OVR;
}
Script_2
public class Script_2 : MonoBehaviour
{
private Script_1 src_1;
public GameObject Front;
void Start()
{
src_1 = (Script_1) GameObject.FindObjectOfType(typeof(Script_1));
src_1.GetComponent<OVRScript >().OVR = Front //I am facing problem here
}
}
Both GameObjects "OVR" and "Front" contain the OVRScript
src_1.GetComponent<OVRScript>().OVR = Front.GetComponent<OVRScript>().OVR;
I don't know or see the OVRScript class but isn't OVR rather a member of Script_1?
And then you would want to use GetComponent on the Front in order to get a component attached to it.
// If possible rather drag your Script_1 in here directly via the Inspector
[SeializeField] private Script_1 src_1;
void Start()
{
// Now I would use find only as fallback
if(!scr_1) src_1 = GameObject.FindObjectOfType<Script_1>();
// then you want to assign the OVR field of the 'src_1' of type 'Script_1'
// and not use 'src_1.GetComponent<OVRScript>()' which would return
// the reference of an 'OVRScript' component attached to the same GameObject as the Script_1
//
// And you want to fill it with the reference of an 'OVRScript' attached to 'Front'
src_1.OVR = Front.GetComponent<OVRScript>();
}
(see [SerializeField])
It would be even better if you directly define
public OVRScript Front;
now if you drag in a GameObject it a) is checked if this GameObject actually has a OVRScript attached, otherwise you can't drop it and b) instead of the GameObject reference already the OVRScript reference is serialized and stored so there is no need for GetComponent anymore:
[SeializeField] private Script_1 src_1;
public OVRScript Front;
void Start()
{
// Now I would use find only as fallback
if(!scr_1) src_1 = GameObject.FindObjectOfType<Script_1>();
src_1.OVR = Front;
}

Variables in script do not show in Inspector (Unity)

I'm trying to learn how to use Unity and following online tutorials but I am currently having a problem that I don't understand how to fix.
I have a Sprite in my scene and I have attached a script to it however in the Inspector it shows the script is there but I cannot see the variables inside? I had this problem previously and it sorted itself out.
What is the cause of this problem/how do I fix it?
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class SpaceShip : MonoBehaviour {
public float speed = 30;
public GameObject theBullet;
private void FixedUpdate()
{
float horzMove = Input.GetAxisRaw("Horizontal");
GetComponent<Rigidbody2D>().velocity = new Vector2(horzMove, 0) *
speed;
}
// Update is called once per frame
void Update () {
if (Input.GetButtonDown("Jump"))
{
Instantiate(theBullet, transform.position, Quaternion.identity);
}
}
}
Edit: The problem was solved by reimporting.
You either need to declare the variables as Public or [SerializeField] for member variables to appear in the inspector. Note that by declaring something as public allows access to the variable from outside the class (from other scripts/classes for example). By default, private is assigned to member variables.
Example:
public class testscript : MonoBehaviour
{
public int foo; // shows up in inspector
[SerializeField] private int bar; // also shows up while still being private
void Start()
{
}
}
Not is a problem, You forget to do something surely.
It is common at first with Unity.
Start again.
In the scene create a new GameObject and add you script.
If the inspector shows not variable:
The varible do not is public (false, if is public in you script)
There is some syntax error in the script!
or
You were not adding the correct script to the GameObject.
There are not many secrets to that, if all is well enough that the variable is public and this outside of a method of the script so that it is seen in the inspector.
One tip, do not use a GetComponent or Instantiate inside a FixedUpdate or Update because they are expensive, save the Rigidbody2D in a variable in the Start and then use it.
Sorry for my English and good luck.

Unity can't acess another class 's instance c#

The first class
public class ArmyManMovement : MonoBehaviour {
public Animator anim;
TextInput check;
// Use this for initialization
void Start () {
anim = GetComponent<Animator> ();
}
The second class
public class TextInput : MonoBehaviour
{
ArmyManMovement check;
void Awake()
{
check = GetComponent<ArmyManMovement> ();
//check.anim.SetBool ("Right", false);
}
//public IEnumerable<string> RemoveWhitespace(string input)
//{
//return new string(input.ToCharArray().Where(c => !Char.IsWhiteSpace(c)).ToArray());
//}
void AcceptStringInput(string userInput)
{
userInput = userInput.ToLower ();
if (userInput == "Open door") {
check.anim.SetBool("Right",true);
}
}
I don't know what 's wrong.I attached the Armyman 's script to the same inspector where textinput is.I don't know what 's wrong,but the value doesn't change and i can't access the animator in armyman 's script.It keeps priniting in the console that the error is (Object refrence not set to instance of object)
If the ArmyManMovement is attached to the-same GameObject the TextInput script is attached to, it should never be null when you perform GetComponent<ArmyManMovement> (); from the TextInput script.
There are really two possible problems here:
1.The TextInput script is also attached to another GameObject. Look in your scene and make sure that it is not. If it is mistakenly attached to another GameObject that that does not have the ArmyManMovement attached to it too, GetComponent<ArmyManMovement> (); will return null which mean that the check variable will be null. See this for how to find this out and fix it.
2.The anim variable is not assigned from the Editor.
First test: Debug.Log(check);.
If it is not null then test: Debug.Log(check.anim);.
If that is null then drag your animator to the anim slot in the ArmyManMovement script.
Note that if Debug.Log(check); is null, you need to go back to #1 and fix that first. Hopefully, you now know how to fix your future Unity null problems.

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