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saving player position while moving between scenes Unity 3D

I've started learning 3D game development and now I've reached the scenes changing.
I looked over the internet and I couldn't find a solution that I can implement in my project.
At this point, I've two scenes, the street which is the main scene, and a bar scene.
I've created a sliding door that has a collider called portal that triggers the scene switch.
I've managed to swap the scene but when I'm trying to go back to my main scene I respawn and the starting point and not at the bar exit. I've tried to save the player position in a temp variable but that didn't work well. what should I do to make my player start at the store exit ?
public class PlayerMotion : MonoBehaviour
{
//...
public static Vector3 playerPosition; // for respawning use
public static bool respawnNeeded = false;
CharacterController cController;
void Update()
{
if(respawnNeeded)
{
cController.transform.position = new Vector3(StreetToBarFFPortal.tempPosition.x,
StreetToBarFFPortal.tempPosition.y,
StreetToBarFFPortal.tempPosition.z);
respawnNeeded = false;
}
//..... some movement code
playerPosition = new Vector3(cController.transform.position.x, cController.transform.position.y, cController.transform.position.z);
}
public class StreetToBarFFPortal : MonoBehaviour
{
public static Vector3 tempPosition;
private void OnTriggerEnter(Collider other)
{
if(other.CompareTag("Player"))
{
int index = SceneManager.GetActiveScene().buildIndex;
if(index==0)
{
PlayerMotion.respawnNeeded = true;
tempPosition = new Vector3(PlayerMotion.playerPosition.x,
PlayerMotion.playerPosition.y,
PlayerMotion.playerPosition.z-4);
}
index = 1 - index;// 1 transfers to 0 and 0 transfers to 1
SceneManager.LoadScene(index);
}
}
}
I also have a GlobalManeger script with a singeltone design pattern if that helps.

You have two options:
Store it in the DontDestroyOnLoad()
Store it in playerprefs before you load the other scene and load it back when the scene is loaded again. Since you're storing a Vector3 then store the x, y and z like this:
PlayerPrefs.SetFloat("X", playerPosition.x);
PlayerPrefs.SetFloat("Y", playerPosition.y);
PlayerPrefs.SetFloat("Z", playerPosition.z);
and load is like this:
float xpos = PlayerPrefs.GetFloat("X");
float ypos = PlayerPrefs.GetFloat("Y");
float zpos = PlayerPrefs.GetFloat("Z");
playerPosition = new Vector3(xpos, ypos, zpos);

You have tempPosition which as I can see used to store player position before teleportation, am I right?
So I can't see where this tempPosition variable came from. Is it static or from a singletone script? Anyway you need to have this variable through scenes. So it should be in the script that has DontDestroyOnLoad() method;

Can only spawn one object at once in unity

In my game I have a game object called ExclamationMark which I want to spawn above enemies heads when the player gets into range and they become "Alerted".
I've made this simple script to do that, but for some reason it will only work on one game object.
My enemy script:
void CheckForPlayer()
{
// Define player and get position
var player = GameObject.FindWithTag("Player");
var playerPos = (int)player.transform.position.x;
if (transform.Find("Graphics"))
{
// Define gameobject position
var enemyPos = transform.Find("Graphics").gameObject.transform.position.x;
// Define range to spawn tiles in
var range = 5;
var rangeInfront = enemyPos + range;
var rangeBehind = enemyPos - range;
if (playerPos >= rangeBehind && playerPos <= rangeInfront)
{
enemyIsActive = true;
if (transform.Find("ExclamationMark"))
{
var exMark = transform.Find("ExclamationMark").gameObject.GetComponent<ExclamationMarkSpawn>();
exMark.SpawnExclamationMark();
}
}
else
{
enemyIsActive = false;
}
}
}
My ! script:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class ExclamationMarkSpawn : MonoBehaviour {
public GameObject spawnPos;
public GameObject exclamationMark;
public GameObject exclamationMarkAudio;
public void SpawnExclamationMark()
{
StartCoroutine(GameObject.FindGameObjectWithTag("MainCamera").GetComponent<CameraShake>().Shake(0.2f, 0.2f, 0.2f));
Instantiate(exclamationMark, spawnPos.transform.position, Quaternion.identity);
if (exclamationMarkAudio)
Instantiate(exclamationMarkAudio, spawnPos.transform.position, Quaternion.identity);
StartCoroutine(DestroyExclamationMark());
}
IEnumerator DestroyExclamationMark()
{
yield return new WaitForSeconds(1);
var children = new List<GameObject>();
foreach (Transform child in transform) children.Add(child.gameObject);
children.ForEach(child => Destroy(child));
}
}

Just to be sure: I assume every player has its own instance of both of your scripts attached (some maybe nested further in their own hierarchy).
I assume that since you are using transform.Find which looks for the object by name within it's own children.
In general using Find and GetComponent over and over again is very inefficient! You should in both classes rather store them to fields and re-use them. Best would be if you can actually already reference them via the Inspector and not use Find and GetComponent at all.
In general finding something by name is always error prone. Are you sure they are all called correctly? Or are others maybe further nested?
Note: Find does not perform a recursive descend down a Transform hierarchy.
I would prefer to go by the attached components. You say it has e.g. a RigidBody. If this is the only Rigidbody component in the hierarchy below your objects (usually this should be the case) then you could instead rather simply use
// pass in true to also get disabled or inactive children
Rigidbody graphics = GetComponentInChildren<Rigidbody>(true);
the same for the ExclamationMarkSpawn
// Would be even beter if you already reference these in the Inspector
[SerializeField] private Rigidbody graphics;
[SerializeField] private ExclamationMarkSpawn exclamationMark;
[SerializeField] private Transform player;
private void Awake()
{
if(!player) player = GameObject.FindWithTag("Player");
if(!graphics) graphics = GetComponentInChildren<Rigidbody>(true);
if(!exclamationMark) exclamationMark = GetComponentInChildren<ExclamationMarkSpawn>(true);
}
private void CheckForPlayer()
{
// If really needed you can also after Awake still use a lazy initialization
// this adds a few later maybe unnecessary if checks but is still
// cheaper then using Find over and over again
if(!player) player = FindWithTag("Player");
if(!graphics) graphics = GetComponentInChildren<Rigidbody>(true);
if(!exclamationMark) exclamationMark = GetComponentInChildren<ExclamationMarkSpawn>(true);
var playerPos = (int)player.position.x;
// always if making such a check also give a hint that something might be missing
if (!graphics)
{
// by adding "this" you can now simply click on the message
// in the console and it highlights the object where this is happening in the hierarchy
Debug.LogWarning("graphics is missing here :'( ", this);
return;
}
// Define gameobject position
var enemyPos = graphics.transform.position.x;
// Define range to spawn tiles in
// this entire block can be shrinked down to
if (Mathf.Abs(playerPos - enemyPos) <= 5)
{
enemyIsActive = true;
if (exclamationMark) exclamationMark.SpawnExclamationMark();
}
else
{
enemyIsActive = false;
}
}
The same also in ExclamationMarkSpawn.cs.
I would additionally only allow 1 exclamation mark being visible at the same time. For example when a player jitters in the distance especially assuming both, the player and the enemy, I would move the entire instantiation to the routine and use a flag. Especially since this is called every frame in Update while the player stays in the range!
Also re-check and make sure your enemies are not maybe referencing the same spawnPos and thus all instantiating their exclamation marks on top of each other.
public class ExclamationMarkSpawn : MonoBehaviour
{
public Transform spawnPos;
public GameObject exclamationMark;
public GameObject exclamationMarkAudio;
[SerializeField] private CameraShake cameraShake;
// only serialized for debug
[SerializeField] private bool isShowingExclamation;
private void Awake()
{
if(!cameraShake) cameraShake = Camera.main.GetComponent<CameraShake>();
// or assuming this component exists only once in the entire scene anyway
if(!cameraShake) cameraShake = FindObjectOfType<CameraShake>();
}
public void SpawnExclamationMark()
{
StartCoroutine(ShowExclamationMark());
}
private IEnumerator ShowExclamationMark()
{
// block concurrent routine call
if(isShowingExclamation) yield brake;
// set flag blocking concurrent routines
isShowingExclamation = true;
// NOTE: Also for this one you might want to rather have a flag
// multiple enemy instances might call this so you get concurrent coroutines also here
StartCoroutine(cameraShake.Shake(0.2f, 0.2f, 0.2f));
Instantiate(exclamationMark, spawnPos.position, Quaternion.identity);
if (exclamationMarkAudio) Instantiate(exclamationMarkAudio, spawnPos.position, Quaternion.identity);
yield return new WaitForSeconds(1);
var children = new List<GameObject>();
foreach (var child in transform.ToList()) children.Add(child.gameObject);
children.ForEach(child => Destroy(child));
// give the flag free
isShowingExclamation = false;
}
}

Try this;
if (transform.Find("ExclamationMark"))
{
var exMark = transform.Find("ExclamationMark").gameObject.GetComponent<ExclamationMarkSpawn>();
exMark.SpawnExclamationMark(transform.position); //Add transform.position here
}
public void SpawnExclamationMark(Vector3 EnemyPos)
{
StartCoroutine(GameObject.FindGameObjectWithTag("MainCamera").GetComponent<CameraShake>().Shake(0.2f, 0.2f, 0.2f));
Instantiate(exclamationMark, EnemyPos, Quaternion.identity);
if (exclamationMarkAudio)
Instantiate(exclamationMarkAudio, EnemyPos, Quaternion.identity);
StartCoroutine(DestroyExclamationMark());
}

Understanding Unity's GameObject.Find(), GetComponent() and objects recycling

New to unity.
So I created a simple a simple muzzle flash particle animation that is supposed to be displayed on enemies gun when the player gets close to him, simulating a shot without the actual bullet. However I get a null reference exception in this part muzzleFlash.Play(); I believe it's because I am not actually getting the muzzle flash component in the start function with the code I have, actually I know that is it after going to in to debug mode I found out. I am having a really hard time figuring out how to access that component. Below is my code and I'm also posting a picture of my hierarchy. Thanks in advance.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class StaticShootingEnemy : MonoBehaviour
{
[SerializeField] private float _range = 12f;
private Transform _player;
private bool _alive;
private float _distance;
private ParticleSystem muzzleFlash;
// Use this for initialization
void Start()
{
_player = GameObject.Find("Player").transform;
_alive = true;
muzzleFlash = (ParticleSystem)this.gameObject.GetComponent("muzzleFLash");
}
// Update is called once per frame
void Update()
{
_distance = Vector3.Distance(this.transform.position, _player.transform.position);
if (_alive && _distance < _range)
AttackPlayer();
}
private void AttackPlayer()
{
//Turning enemy to look at player
transform.LookAt(_player);
Ray ray = new Ray(transform.position, transform.forward);
RaycastHit hit;
if (Physics.SphereCast(ray, 0.75f, out hit))
{
//TODO: Fix enemy shooting fast when gettting close to him.
GameObject hitObject = hit.transform.gameObject;
if (hitObject.GetComponent<PlayerController>())
{
muzzleFlash.Play();
Debug.Log("Player Hit!");
}
else
muzzleFlash.Stop();
}
}
public void SetAlive(bool alive)
{
_alive = alive;
}
}

You probably have an object "muzzleFlash" as child to object your script attached to. So, in this case you'd better have a reference to your ParticleSystem object that is called muzzleFlash.
[SerializeField] private ParticleSystem muzzleFlash; // drag and drop your ParticleSystem muzzleFlash in inspector
or at least you could find that muzzleFlash like this
GameObject muzzleFlashObj = GameObject.Find("muzzleFlash");
ParticleSystem muzzleFlash = muzzleFlashObj.GetComponent<ParticleSystem>();
In your case it's null because there is probably no component that is called MuzzleFlash on that object. The component you want to get is ParticleSystem.

What component is the staticshootingenemy script on? if it is not on the same component as the particle system then its not finding it because this.gameObject.GetComponent("muzzleFLash") does not exist on that component. You can use GameObject.Find("muzzleFLash") to search for the particle system.

So back to your comment, you could implement something like a pool for your muzzle flashes.
public class MuzzleFlashEffect : MonoBehaviour
{
[SerializeField] private ParticleSystem particleEffect;
private Queue<MuzzleFlashEffect> poolQueue;
public void SetPoolQueue(Queue<MuzzleFlashEffect> queue)
{
poolQueue = queue;
}
public void Play()
{
StartCoroutine(Playing());
}
private IEnumerator Playing()
{
particleEffect.Play();
while (particleEffect.isPlaying)
{
yield return null; // wait until particle animation is done, then recycle effect
}
particleEffect.Stop();
poolQueue.Enqueue(this); // recycle this effect
}
// you can do the same thing for Animation as well, or even write some abstract PoolableVFX class that would be usefull for Animation , ParticleSystems etc..
}
//assume you have some game controller that manage what is going on in the scene
public class GameController : MonoBehaviour
{
[SerializeField] private MuzzleFlashEffect muzzleFlashPrefab;
private Queue<MuzzleFlashEffect> poolQueue = new Queue<MuzzleFlashEffect>(10); // 10 is enough i guess and it's good to set it at instantiation to avoid memory fragmentation
private MuzzleFlashEffect GetMuzzleFlash(Vector3 pos, Quaternion rot)
{
MuzzleFlashEffect muzzleFlash;
// if we already have some effects, then play them, otherwise make a new one and recycle it then
if (poolQueue.Count > 0)
{
muzzleFlash = poolQueue.Dequeue();
}
else
{
muzzleFlash = Instantiate(muzzleFlashPrefab);
muzzleFlash.SetPoolQueue(poolQueue);
}
muzzleFlash.transform.position = pos;
muzzleFlash.transform.rotation = rot;
return muzzleFlash;
}
void Update()
{
// your fancy logic ...
GameObject mutantGunEnd = new GameObject("mutant");
//assume that here you want your muzzle flash effect, so you do:
var muzzleFlash = GetMuzzleFlash(mutantGunEnd.transform.position, mutantGunEnd.transform.rotation); // or you might want to pass mutantGunEnd.transform.forward instead, it depends...
muzzleFlash.Play();
// your fancy logic ...
}
}
So, in this case you have only as many instance of ParticleEffect as you need and saving some resources. You could also create a universal generic pool for any type of object you want to recycle. (you want to recycle instead of instantiation, cuz Instantiation is cpu expensive).
M.b this is a bit overkill here, but i just wanted to share how would i think about this 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.

Unity c# Code working in one script but not in other?

Hey guys so I have this really strange problem, so basically what happens is the player runs into the box (OnTriggerEnter function) and a weapon will show on the character and the box will spawn to another location. Except I tried to make a separate script because the script that it works on is for spawning boxes. I didn't want it in the same script because not as neat.
So this is my code for the script where it doesn't work:
public class ChangeGun : MonoBehaviour {
public Sprite gunSprite;
private string[] weapons = { "Pistol", "Shotgun", "Ak47", "Bazooka" };
public GameObject currentGun;
public void AddGunToPlayer()
{
//int randomNumber = Random.Range(0, 4);
currentGun.GetComponent<SpriteRenderer>().sprite = gunSprite;
}
}
And this is the script where it works (keep in mind I used the EXACT same code, ignore all the code in this script except the for the 2 variables and the OnTriggerEnter Function.)
public class BoxGenerator : MonoBehaviour
{
public GameObject currentGun;
public Sprite gunSprite;
public Vector3[] boxPositions;
public GameObject box;
public GameObject startingBox;
int randomNumber;
// Use this for initialization
void Start()
{
//random number between 0-10 thats vector size
randomNumber = Random.Range(0, 10);
//instantiate the starting box
startingBox = Instantiate(box);
//set starting box to new location
startingBox.transform.position = boxPositions[randomNumber];
//set tag to box
startingBox.tag = "box";
}
void Update()
{
randomNumber = Random.Range(0, 10);
}
void OnTriggerEnter(Collider col)
{
if (col.GetComponent<Collider>().tag == "box")
{
startingBox.transform.position = boxPositions[randomNumber];
currentGun.GetComponent<SpriteRenderer>().sprite = gunSprite;
}
}
}
Keep in mind when I tried to use the old script under this line "currentGun.GetComponent().sprite = gunSprite;"
I pasted this code and got the null reference exception.
ChangeGun cg = new ChangeGun();
cg.AddGunToPlayer();

ChangeGun is null since you didn't set it. You said you set it in the inspector, but in your question you created in in the code so it will have the default values.
ChangeGun cg = new ChangeGun(); // cg.currentGun is null
cg.AddGunToPlayer(); // Trying to access cg.currentGun
I suppose you have set in in the inspector, so instead of creating new ChangeGun, you need to get the component you created in Inspector:
ChangeGun cg = GetComponent<ChangeGun>();
cg.AddGunToPlayer();