Develop Reference

How do i get one object to track and move towards another object

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class EnemyControler : MonoBehaviour
{
private Transform player;
// Start is called before the first frame update
void Start()
{
//Note in this case we're saving the transform in a variable to work with later.
//We could save the player's game object (and just remove .transform from the below) but this is cleaner
var player = GameObject.FindWithTag("Player").transform;
}
// Update is called once per frame
void Update()
{
//**** The code below you need to modify and move into your own method and call that method from here.
//**** Don't overthink it. Look at how Start() is defined. Your own Move method would look the exact same.
//**** Experiment making it private void instead of public void. It should work the same.
//How much will we move by after 1 second? .5 meter
var step = .5f * Time.deltaTime; // 5 m/s
var newPosition = Vector3.MoveTowards(transform.position, player, step);//This is one way to move a game object by updating the transform. Watch the videos in this module and it should become apparent what goes here.
}
}
The transform does not map to the tagged player. I was trying to get an enemy in unity to move towards a moving player for a class, but I'm completely lost.

You had three issues in your code. The first was that you were defining a new player variable in the Start method. This hid the player member field you defined earlier.
The second issue was that you were getting a value to move towards, but you weren't assigning that value to the current objects position.
The third issue was that you were feeding in a Transform into the MoveTowards method, when you should have been feeding in a Vector2.
The code below should rectify these issues.
public class EnemyControler : MonoBehaviour
{
private Transform _player;
void Start()
{
_player = GameObject.FindWithTag("Player").transform;
}
void Update()
{
var step = .5f * Time.deltaTime;
transform.position = Vector3.MoveTowards(transform.position, _player.position, step);
}
}

Try doing something like this ive used this in the past to do something similar once you understand the code change it to what you desire
public int minRange;
private Transform target = null;
private void OnTriggerEnter(Collider other)
{
if (other.tag == "Player")
target = other.transform;
}
private void OnTriggerExit(Collider other)
{
if (other.tag == "Player")
target = null;
}
void update()
{
transform.LookAt(target);
float distance = Vector3.Distance(transform.position,
target.position);
bool tooClose = distance < minRange;
Vector3 direction = tooClose ? Vector3.back : Vector3.forward;
if (direction == Vector3.forward)
{
transform.Translate(direction * 6 * Time.deltaTime);
}
else
{
transform.Translate(direction * 3 * Time.deltaTime);
}
}

Unity - What is OOP - Null Reference Exception

im kind of newbie to unity and object oriented programming. Recently im trying to clone Cube Surfer mobile game. Basic idea from my view is this ;
-When we triggered to collactable cubes which consist script will be duplicated and it will be belong the main cube parent as child object then triggered cube will be destroyed.(After positioning)
-Later this duplicate child objects(cubes) will do the same when they enter trigger area of other collectable cubes(those will be the same prefab but did not yet create a prefab)
Im trying to collect(create a clone of it position and destroy the object) cubes. For first cube, I added some code to my movement script which is below.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class Movement : MonoBehaviour
{
public GameObject addup;
Rigidbody rb;
float controlSpeed = 1.25f;
float forwardMovementSpeed = 10f;
private Vector3 axisGet;
float deathTime;
public int collected;
// Start is called before the first frame update
void Start()
{
rb = gameObject.GetComponent<Rigidbody>();
collected = 0;
}
// Update is called once per frame
void FixedUpdate()
{
axisGet = new Vector3(0, 0, Input.GetAxis("Horizontal"));
rb.MovePosition(transform.position + Vector3.left * forwardMovementSpeed * Time.deltaTime + axisGet * controlSpeed * Time.deltaTime);
}
private void OnTriggerEnter(Collider other)
{
if(other.tag=="add up")
{
gameObject.transform.position += Vector3.up;
var newObject = Instantiate(addup.gameObject, Vector3.zero, Quaternion.identity);
newObject.transform.parent = transform;
newObject.transform.position = gameObject.transform.position + Vector3.down;
Destroy(other.gameObject);
newObject.GetComponent<BoxCollider>().isTrigger = false;
collected++;
}
}
}
WORKED WITHOUT ERROR BUT THEN, I applied the same method to collectable cubes scripts.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class UpNdown : MonoBehaviour
{
void Start()
{
}
// Update is called once per frame
void Update()
{
}
private void OnTriggerEnter(Collider other)
{
if (other.tag == "add up")
{
GameObject parentTransform;//?????????
parentTransform = gameObject.GetComponentInParent<GameObject>(); //get first cube component
parentTransform.transform.position += Vector3.up; //first cube one unit up
GameObject newObject; // ?????????
newObject = Instantiate(other.gameObject, Vector3.zero, Quaternion.identity) as GameObject; //???????????
Debug.Log(newObject);
var collect = parentTransform.GetComponent<Movement>().collected;
if (other != null)
{
Destroy(other.gameObject); //destroy triggered collactable
}
newObject.transform.parent = parentTransform.transform; //setting parent to new cube
newObject.transform.position = parentTransform.transform.position + Vector3.down * (collect + 1); //setting position of new cube
newObject.GetComponent<BoxCollider>().isTrigger = false; //prepare the below cubes(new cubes) for trigger with other collactable cubes
collect++;
}
}
}
And, I had nullexception error in every line in ontriggerenter method then, I changed(added) the lines with question marks. So, I get
ArgumentException: GetComponent requires that the requested component 'GameObject' derives from MonoBehaviour or Component or is an interface.
UnityEngine.GameObject.GetComponentInParent[T] (System.Boolean includeInactive) (at :0)
UnityEngine.GameObject.GetComponentInParent[T] () (at :0)
UpNdown.OnTriggerEnter (UnityEngine.Collider other)
I thought, I understood the OOP instance idea which objects in the scenes are instances scripts has their own value... but i dont understand that while I was operating on a instance why it is null in the memory :((((((((((((( if PC can't access how instantiates the object ?
SORRY I WRITE THIS LONG BUT IM ABOUT THE EDGE AGAIN I DON'T WANT TO QUIT BECAUSE OF FACING THIS PROBLEM AGAIN
TY FOR YOUR ANSWERS, ALREADY APPRECIATED :)

GameObject is no component (it is rather a container of all components attached to it!)
=> you can't get it using GetComponent or GetComponentInParent at all. (Btw Note that GetComponentInParent starts the search on this object itself first before bubling up the hierarchy so either way this isn't what you want to use).
What you want is simply transform.parent to get the Transform component of the parent object of the object this script is attached to (assuming the rest of your code does what it should)
private void OnTriggerEnter(Collider other)
{
// Rather use CompareTag instead of string ==
// The latter silently fails in case of typos making your debugging life miserabel
// it is also slightly less efficient
if (!other.CompareTag("add up")) return;
// Get the parent of this object
var parentTransform = transform.parent;
// Cache this you will need it later see below
var parentMovement = parentTransform.GetComponent<Movement>();
var collect = parentMovement.collected;
parentTransform.position += Vector3.up;
// By using the correct type you want later you can skip GetComponent
var newObjectCollider = Instantiate(other, Vector3.zero, Quaternion.identity);
Debug.Log(newObjectCollider);
Destroy(other.gameObject);
newObjectCollider.transform.parent = parentTransform;
newObjectCollider.transform.position = parentTransform.position + Vector3.down * (collect + 1);
newObjectCollider.isTrigger = false;
// This does absolutely nothing. Numeric values are passed by value and there is no connection
// between your local variable and the component you got it from
//collect++;
// you probably rather want to increase
parentMovement.collected++;
}
Or alternatively since you anyway have a specific component on your parent object you could also do
// Instead directly get this component
var parentMovement = GetComponentInParent<Movement>();
// Then wherever needed access the transform through it
var parentTransform = parentMovement.transform;
...
I'm quite sure though that the other way round it is more efficient since you already know exactly which parent you are searching the component on.
Or - and this would probably be the best option - cache that parent information once right away:
// If possible already reference this vis the Inspector
[SerializeField] private Movement parentMovement;
private Transform parentTransform;
private void Awake ()
{
if(! parentMovement) parentMovement = GetComponentInParent<Movement>();
parentTransform = parentMovement.transform;
}

Ty sir my first code was nearly the same of your first answer but didn't work again at least for error.
private Transform parentTransform;
private void Awake ()
{
if(! parentMovement) parentMovement = GetComponentInParent<Movement>();
parentTransform = parentMovement.transform;
}
But this worked, I guess the problem I need to define instances to class so they don't disappear instantly on the trigger function or direct I need to define them to class.
Anyway, thank you derHugo now need to solve different problems :D

How to shoot in Unity in both directions?

I am very new to Unity and I never coded in C# before neither have I used Unity in the past. All I know is Java and Python. I knew Java since senior year of high school now I am a sophomore in college. I made my project, which consists of my human character, which is supposed to shoot bullets at 12 jaguars. I already implemented all of this from the 2d UFO sample Unity gives us. I have a png picture for my bullet. I really do not know how to implement a bullet. I am required to have the bullet shoot out in two directions. I am starting off gradually by learning how to basic shoot (one direction). I referred to this link and added it to my program and it will not compile after I added the bullet code. I create a sphere into the Unity program as the website said to do and I set the image as the png bullet.
https://unity3d.com/learn/tutorials/temas/multiplayer-networking/shooting-single-player
Now here is my code. I downloaded the free latest version of Unity by the way. My game is 2D by the way. It is just cartoons.
using UnityEngine;
using System.Collections;
//Adding this allows us to access members of the UI namespace including Text.
using UnityEngine.UI;
public class CompletePlayerController : MonoBehaviour {
public float speed; //Floating point variable to store the player's movement speed.
public Text countText; //Store a reference to the UI Text component which will display the number of pickups collected.
public Text winText; //Store a reference to the UI Text component which will display the 'You win' message.
private Rigidbody2D rb2d; //Store a reference to the Rigidbody2D component required to use 2D Physics.
private int count; //Integer to store the number of pickups collected so far.
public GameObject bulletPrefab;
public Transform bulletSpawn;
// Use this for initialization
void Start()
{
//Get and store a reference to the Rigidbody2D component so that we can access it.
rb2d = GetComponent<Rigidbody2D> ();
//Initialize count to zero.
count = 0;
//Initialze winText to a blank string since we haven't won yet at beginning.
winText.text = "";
//Call our SetCountText function which will update the text with the current value for count.
SetCountText ();
}
//FixedUpdate is called at a fixed interval and is independent of frame rate. Put physics code here.
void FixedUpdate()
{
//Store the current horizontal input in the float moveHorizontal.
float moveHorizontal = Input.GetAxis ("Horizontal");
//Store the current vertical input in the float moveVertical.
float moveVertical = Input.GetAxis ("Vertical");
//Use the two store floats to create a new Vector2 variable movement.
Vector2 movement = new Vector2 (moveHorizontal, moveVertical);
//Call the AddForce function of our Rigidbody2D rb2d supplying movement multiplied by speed to move our player.
rb2d.AddForce (movement * speed);
if (!isLocalPlayer)
{
return;
}
var x = Input.GetAxis("Horizontal") * Time.deltaTime * 150.0f;
var z = Input.GetAxis("Vertical") * Time.deltaTime * 3.0f;
transform.Rotate(0, x, 0);
transform.Translate(0, 0, z);
if (Input.GetKeyDown(KeyCode.Space))
{
Fire();
}
}
void Fire()
{
// Create the Bullet from the Bullet Prefab
var bullet = (GameObject)Instantiate (
bulletPrefab,
bulletSpawn.position,
bulletSpawn.rotation);
// Add velocity to the bullet
bullet.GetComponent<Rigidbody>().velocity = bullet.transform.forward * 6;
// Destroy the bullet after 2 seconds
Destroy(bullet, 2.0f);
}
public override void OnStartLocalPlayer ()
{
GetComponent<MeshRenderer>().material.color = Color.blue;
}
//OnTriggerEnter2D is called whenever this object overlaps with a trigger collider.
void OnTriggerEnter2D(Collider2D other)
{
//Check the provided Collider2D parameter other to see if it is tagged "PickUp", if it is...
if (other.gameObject.CompareTag ("PickUp"))
{
//... then set the other object we just collided with to inactive.
other.gameObject.SetActive(false);
transform.localScale += new Vector3(0.1f, 0.1f, 0);
//Add one to the current value of our count variable.
count = count + 1;
//Update the currently displayed count by calling the SetCountText function.
SetCountText ();
}
}
//This function updates the text displaying the number of objects we've collected and displays our victory message if we've collected all of them.
void SetCountText()
{
//Set the text property of our our countText object to "Count: " followed by the number stored in our count variable.
countText.text = "Count: " + count.ToString ();
//Check if we've collected all 12 pickups. If we have...
if (count >= 12)
//... then set the text property of our winText object to "You win!"
winText.text = "You win!";
}
}
Other class
using UnityEngine;
using System.Collections;
public class CompleteCameraController : MonoBehaviour {
public GameObject player; //Public variable to store a reference to the player game object
private Vector3 offset; //Private variable to store the offset distance between the player and camera
// Use this for initialization
void Start ()
{
//Calculate and store the offset value by getting the distance between the player's position and camera's position.
offset = transform.position - player.transform.position;
}
// LateUpdate is called after Update each frame
void LateUpdate ()
{
// Set the position of the camera's transform to be the same as the player's, but offset by the calculated offset distance.
transform.position = player.transform.position + offset;
}
}

You need to follow all the steps in the tutorial link you shared. Looks like you have copied pieces of code and used it in your controller class. OnStartLocalPlayer is marked as overridden, but it is not in Monobehaviour. It is defined in NetworkBehaviour. You have an error due to this. As mentioned in the other comments, the console error tells you where the problem is.

Unity 2D - sprite flicker while follow object

im creating simple script which tells gameobject that it needs to follow other gameobject in defined distance.
code:
void Update()
{
objPos = GameObject.FindGameObjectWithTag("Player").transform.position;
transform.position = new Vector3(objPos.x + 0.5f, objPos.y + 0.5f);
}
problem is: following gameobject is flickering. When you watch it, it appears to be few frames behind followed gameobject. I noticed it before in my earlier prototype but now its crutial for my new game. So i think its pretty common issue.
Is there sollution for this unwanted behaviour?
Thanks

GameObject.FindGameObjectWithTag("Player") has high performance cost, instead of using it each frame, hold an instance of the player. If the player is constant in the scene,
public Transform playerTransform;
void Update()
{
transform.position = playerTransform.position + new Vector3(0.5f, 0.5f);
}
and then assign the Player transform in Unity editor to this object using inspector. (Or dynamically in the code)
If your Player object gets destroyed and a new one instantiates once in a while, you can either assign the new one to the follower objects, or use a simple accessor method like this:
Transform _playerTransform;
Transform playerTransform
{
get
{
if(_playerTransform == null)
{
_playerTransform = GameObject.FindGameObjectWithTag("Player").transform;
}
return _playerTransform;
}
}
void Update()
{
transform.position = playerTransform.position + new Vector3(0.5f, 0.5f);
}

Issues with a script that should follow another GameObject's position

I currently have a little issue with a script I made. Basically, I want to create a script that makes its GameObject (let's name it A) and follows another GameObject's (named B) position. I know a simple way to do that would be to parent A to B, but I'm not doing it for two reasons :
1) I want to be able to apply a smoothing (whose value I can change) on A's movement;
2) I want to be able to make A follow B's position and/or rotation at will.
Here is the script I wrote :
using UnityEngine;
using System.Collections;
public class FollowGameObject : MonoBehaviour {
public GameObject m_GameObjectToFollow;
public bool m_FollowPosition;
public bool m_FollowRotation;
public float m_PositionSmoothing;
public float m_RotationSmoothing;
// Should not be changed once set
public bool m_UseOffsetPosition;
public bool m_UseOffsetRotation;
private Vector3 m_PositionOffset;
private Quaternion m_RotationOffset;
void Start () {
m_PositionSmoothing = Mathf.Clamp(m_PositionSmoothing, 0.0f, 1.0f);
m_RotationSmoothing = Mathf.Clamp(m_RotationSmoothing, 0.0f, 1.0f);
if (m_UseOffsetPosition)
{
m_PositionOffset = transform.position - m_GameObjectToFollow.transform.position;
} else {
m_PositionOffset = Vector3.zero;
}
if (m_UseOffsetRotation)
{
m_RotationOffset = transform.rotation * Quaternion.Inverse(m_GameObjectToFollow.transform.rotation);
} else {
m_RotationOffset = Quaternion.identity;
}
}
void FixedUpdate () {
if (m_FollowPosition) {
Vector3 goalPosition = m_GameObjectToFollow.transform.position + m_PositionOffset;
transform.position = Vector3.Lerp(transform.position, goalPosition, m_PositionSmoothing);
//transform.Translate(newPosition - transform.position, Space.World);
}
if (m_FollowRotation) {
Quaternion goalRotation = m_GameObjectToFollow.transform.rotation * m_RotationOffset;
transform.rotation = Quaternion.Lerp(transform.rotation, goalRotation, m_RotationSmoothing);
}
}
I hope the code is easily understandable, if not feel free to ask.
In any case, once I attach this script to A and assign its m_GameObjectToFollow attribute to B (B is parented to a character controller, and I parented a sphere renderer to A so I can see if it follows B correctly), I notice that A is indeed following B, but I see that its position (through the sphere renderer) is "fluctuating" between the "right" position (B's) and another one. Visually, the sphere is flickering.
I tried putting the smoothing values to 1 (i.e. A should always be at B's position/rotation). I still see a flickering.
Could someone explain to me what I did wrong?
EDIT : Seems like I'm using Lerp the wrong way with its last value. I modified the script to use speed values instead of smoothing values, but still the same problem when I try to create some smooth movements (with lower speed values).
I have troubles explaining the problem properly. The best way to see what the problem look like would be to experience it yourself :
1) Create a scene with a terrain and a character controller in it;
2) Parent the main camera to the controller (so that it always follows it);
3) Create a new GameObject with a renderer (for example, a sphere), not parented to any other GameObject, but attach the following script to it :
using UnityEngine;
using System.Collections;
public class FollowGameObject : MonoBehaviour {
public GameObject m_GameObjectToFollow;
public bool m_FollowPosition;
public bool m_FollowRotation;
// Betzeen 0 and 1. 1 means that a complete unsmoothed follow
public float m_PositionFollowSpeed;
public float m_RotationFollowSpeed;
// Should not be changed once set
public bool m_UseOffsetPosition;
public bool m_UseOffsetRotation;
private Vector3 m_PositionOffset;
private Quaternion m_RotationOffset;
void Start () {
if (m_UseOffsetPosition)
{
m_PositionOffset = transform.position - m_GameObjectToFollow.transform.position;
} else {
m_PositionOffset = Vector3.zero;
}
if (m_UseOffsetRotation)
{
m_RotationOffset = transform.rotation * Quaternion.Inverse(m_GameObjectToFollow.transform.rotation);
} else {
m_RotationOffset = Quaternion.identity;
}
}
void Update () {
if (m_FollowPosition) {
Vector3 goalPosition = m_GameObjectToFollow.transform.position + m_PositionOffset;
transform.position = Vector3.Slerp(transform.position, goalPosition, Time.deltaTime * m_PositionFollowSpeed);
}
if (m_FollowRotation) {
Quaternion goalRotation = m_GameObjectToFollow.transform.rotation * m_RotationOffset;
transform.rotation = Quaternion.Slerp(transform.rotation, goalRotation, Time.deltaTime * m_RotationFollowSpeed);
}
}
}
With :
m_GameObjectToFollow = the character controller GameObject;
m_FollowPosition = true;
m_PositionFollowSpeed = 10;
(The other parameters values don't matter for this test)
Now start the scene and move the character controller, I will see the sphere flickering during motion, but if you stop moving it will smoothly go to the controller.

You are using FixedUpdate. Is there any special reason to do so?
Anyway, try to use Update or LateUpdate instead of FixedUpdate or check Fixed Timestep in Project Settings => Time.
Also read the answer to this question for more information about difference between Update and FixedUpdate.