Develop Reference

Gameobject not spawning in desired position after InvokeRepeating and Instantiate

Context
Hello, currently creating a clone of "Crossy Road" and what I'm trying to do is to spawn my moving object called "Vehicle" at a random speed and rate of spawn. This is also applicable to "Plank", but I will start first with the vehicle. So far, everything is working fine as intended for the game mechanics, but I would like to finalize with this issue so it is fully functional in terms of playability.
Problem
My issue now is I 3 different spawns objects: grass, river, and road. Each object holds other objects (let's call it spawners) depending of what field is being spawn. For example, if grass field object is spawned, it will spawn trees depending in a random varied selection. Another example is with road field. When the road is spawned, a vehicle will be spawned from either left or right in its current initial position. This vehicle will moves as intended with a random speed, but not with the original spawn position and rate (as shown in the GIF. The vehicle spawns in the middle of the road and not in the beginning of the left/right road).
As far I'm aware, my rate is currently unused because it is not the main issue I want to solve. However, the issue now is with the transform position not working as I have pictured in my head. So what is happening is that when the road is spawned again, the vehicle is spawned in the middle of the trajectory instead of resetting to the beginning.
Also, I have noticed that when I print the vehicle object, the Z-axis has a weird number compared to the original position.
Attempts done
I have been thinking that maybe it is the way I have set everything up. I have 4 vehicle objects with a child object called "Tank". However, in each vehicle object, I'm using SetActive(...) only and not really reusing the object itself to the beginning. Later on, I want to organize this spaghetti code and optimize it (e.g ObjectPool to spawn my roads and other GameObjects after hitting a certain range, adding a player range detection to spawn a field to name a few).
To be honest, my whole code feels bloated for something simple. This will be fixed once everything is working accordingly.
Code (DISCLAIMER: there is the possibility that there are unused variables)
SpawnManager.cs (some links provided too from learning to make this)
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
/*
** Weighted randomness: https://forum.unity.com/threads/random-numbers-with-a-weighted-chance.442190/
** Scriptable Object Weight spawn example: https://www.youtube.com/watch?v=FCksj9ofUgI&ab_channel=LlamAcademy
** From scratch loot tables with Scriptable Objects to make a loot table: https://www.youtube.com/watch?v=tX3RWsVLnzM&ab_channel=GregDevStuff
** Creating a random with an animation curve: https://www.youtube.com/watch?v=zw1OERK5xvU&ab_channel=HamzaHerbou
** Random Vehicle position spawn (maybe this can help me): https://stackoverflow.com/questions/51312481/move-spawn-object-to-random-position
*/
public class SpawnManager : MonoBehaviour
{
public GameObject Player;
public Spawn[] Field;
public GameObject[] SpawnObjectTrees;
public GameObject[] SpawnObjectVehicles; //different vehicles
public GameObject[] SpawnObjectPlanks; //3 sizes (small, medium, large)
private PlayerControl2 playerControlScript;
private int distancePlayer;
private int toggle;
private bool keepSpawning;
bool vehicleFlag = false;
bool plankFlag = false;
public float randomNumSpawn;
void Awake()
{
keepSpawning = true;
playerControlScript = GameObject.Find("PlayerObject").GetComponent<PlayerControl2>();
InvokeRepeating("Spawner", 3f, randomNumSpawn);
}
void Update()
{
if (Input.GetButtonDown("up") && !playerControlScript.gameOver)
SpawnField();
}
void Spawner()
{
bool activeLeft = false;
bool activeRight = false;
if (vehicleFlag)
{
print(initialObjectSpawn);
for (int i = 0; i < SpawnObjectVehicles.Length; i++)
{
print($"{SpawnObjectVehicles[i]}: {SpawnObjectVehicles[i].transform.position}"); //Here I get the weird position.z values pretty wonky
toggle = Random.Range(0, 2);
if (toggle == 1 && !activeLeft)
{
activeLeft = true;
SpawnObjectVehicles[i].SetActive(true);
}
if (toggle == 0 && !activeRight)
{
activeRight = true;
SpawnObjectVehicles[i].SetActive(true);
}
else
SpawnObjectVehicles[i].SetActive(false);
}
}
}
void SpawnField()
{
//I want to spawn the vehicles, planks, and trees in sets accordingly to the field (grass, river, road)
//For vehicles and planks, they can move horizontally from either -z or z boundaries
//NOTE: keepSpawning may be useless if i have a playerControlScript.gameOver already in here
if (keepSpawning)
{
distancePlayer += 3;
Vector3 intPos = new Vector3(0, 0, 0);
int i = Random.Range(0, 1000);
for (int j = 0; j < Field.Length; j++)
{
if (i >= Field[j].minProbabilityRange && i <= Field[j].maxProbabilityRange)
{
intPos = new Vector3(distancePlayer, -1f, 0);
GameObject Surface = Instantiate(Field[j].spawnField);
if (Surface.CompareTag("Grass"))
TreeToggle();
if (Surface.CompareTag("Road"))
{
vehicleFlag = true;
VehicleToggle();
}
// if (Surface.CompareTag("River")) this will be the same as vehicle
// {
// plankFlag = true;
// PlankToggle();
// }
//Add spawn for vehicles and planks with given spawnrate/spawn intervals
Surface.transform.position = intPos;
vehicleFlag = false;
plankFlag = false;
}
}
}
}
void TreeToggle()
{
int counter = 0;
for (int i = 0; i < SpawnObjectTrees.Length; i++)
{
int toggle = Random.Range(0, 2); //[0, 2)
if (toggle == 1 && counter < 5) //True and when there are already 5-4 trees to toggle
{
counter++;
SpawnObjectTrees[i].SetActive(true);
}
else //fills the rest to inactive Trees
SpawnObjectTrees[i].SetActive(false);
}
}
void VehicleToggle()
{
// I have Left and Right with 2 vehicles in each. My goal is to setActive one of them each side at a time with a different interval spawnrate and speed
Spawner();
}
void PlankToggle()
{
Spawner();
}
}
[System.Serializable]
public class Spawn
{
public GameObject spawnField;
public float minProbabilityRange = 0.0f;
public float maxProbabilityRange = 0.0f;
}
Hierarchy/Inspector
If there is any information you want to know, feel free to ask and I will make a quick edit to fulfill these goals. Again, thank you for your time and appreciate it :D I hope you are having a good day!

GameObject.FindGameObjectsWithTag("Enemy").Length off by one for some reason?

so I'm wanting to pause the game once the amount of enemies hits 0. So I'm using GameObject.FindGameObjectsWithTag("Enemy").Length to find the number of enemies. I put this in a function that's called right when the enemies are instantiated so I can see the length go to 4, as there's 4 enemies spawning. When an enemy is killed the function is called again where the length is printed to console again. For some reason, on the first enemy killed the count repeats with a 4 again despite there only being 3 enemies. Once another enemy is killed it reports 3 when there's actually 2 and so on until I get to 1 when there's 0 enemies.
Here's the first snippet of code:
public class EnemyList : MonoBehaviour
{
public List<GameObject> weakMobs = new List<GameObject>();
public List<GameObject> mediumMobs = new List<GameObject>();
public List<GameObject> bossMobs = new List<GameObject>();
public List<Transform> spawningChildren = new List<Transform>();
public static int mobCount;
void Start()
{
for (int i = 0; i < spawningChildren.Count; i++)
{
GameObject newWeakMob = Instantiate(weakMobs[0], spawningChildren[Random.Range(0, 4)]) as GameObject;
}
CheckMobCount();
}
public void CheckMobCount()
{
mobCount = GameObject.FindGameObjectsWithTag("Enemy").Length;
print(mobCount);
}
The next piece of code is where the enemy is killed and the CheckMobCount() is called again.
public void TakeDamage()
{
enemyCurrentHealth -= 25;
enemyHealthBar.SetHealth(enemyCurrentHealth);
if (enemyCurrentHealth == 0)
{
Destroy(this.gameObject);
enemyList.CheckMobCount();
//needs death animations
}
}
Here's the console messages:
Console of printed lengths
I'm self taught so I apologize if this is elementary. I've tried doing this several different ways and this is the closest I've been but I'm open to new ideas as well.
Thank you!!

As noted in this answer, the object is not actually destroyed in the current frame.
From the documentation:
The object obj is destroyed immediately after the current Update loop… Actual object destruction is always delayed until after the current Update loop, but is always done before rendering.
I also agree that using DestroyImmediate() is a bad idea.
Ultimately, your question seems to really be about pausing the game when the enemy count reaches 0, which unfortunately hasn't actually been answered yet.
In fact, you don't really need to do anything different except move the check for the enemy count to the beginning of the Update() method, and pause the game there if it's 0. Then you'll find that the component for the enemy has been destroyed at that point.
Presumably enemies are spawned before the update loop starts (i.e. before the first frame), but if not then you can use whatever logic you're already using to decide that new enemies need to be spawned, to detect the fact that you haven't spawned any yet and avoid pausing before the enemies have spawned.

Here you have attached your script to your enemy instances. And they are still alive when you are querying for the number of enemies left.
You should do the following:
public class Enemy: MonoBehaviour
{
public static int EnemyCount = 0;
private void Start()
{
EnemyCount++;
}
private void OnDestroy()
{
EnemyCount--;
}
}
And then you can query the enemy count from anywhere but just excessing the EnemyCount by Enemy.EnemyCount.
If you want to get a more difficult example then you can check out this Game Dev tutorial: https://www.youtube.com/watch?v=LPBRLg4c5F8&t=134s

Destroy is actually executed at the end of the frame. There is DestroyImmediate that is executed immidiatelly but it's not recommended to be used. What I would do is to add a field or a property to identify whether the enemy is still alive and then to check against it. Something like:
class Enemy : MonoBehaviour
{
public bool IsAlive { get; set; } = true;
}
public class EnemyList : MonoBehaviour
{
//...
public void CheckMobCount()
{
mobCount = GameObject.FindGameObjectsWithTag("Enemy").Select(x => x.GetComponent<Enemy>()).Count(x => x.IsAlive);
print(mobCount);
}
}
And then:
public void TakeDamage()
{
enemyCurrentHealth -= 25;
enemyHealthBar.SetHealth(enemyCurrentHealth);
if (enemyCurrentHealth == 0)
{
Destroy(this.gameObject);
this.GetComponent<Enemy>().IsAlive = false;
enemyList.CheckMobCount();
//needs death animations
}
}
This can be further optimized to store the Enemy somewhere and not use GetComponent every time but you get the idea.

As already mentioned by others the issue is that Destroy is executed delayed.
Actual object destruction is always delayed until after the current Update loop, but is always done before rendering.
You could simply count only the GameObjects that are still alive, those for which the bool operator is true.
Does the object exist?
It will be false for objects destroyed in that same frame.
E.g. using Linq Count
using System.Linq;
....
mobCount = GameObject.FindGameObjectsWithTag("Enemy").Count(e => e);
which basically equals doing
mobCount = 0;
foreach(e in GameObject.FindGameObjectsWithTag("Enemy"))
{
if(e) mobCount++;
}
There is no need for an additional property or Component.

I am suggesting you to use “DestroyImmediate” instead of “Destroy”，Then look at the result.
I have a better idea, why not just use static variables when spawning enemies?
void Start()
{
for (int i = 0; i < spawningChildren.Count; i++)
{
GameObject newWeakMob = Instantiate(weakMobs[0],
spawningChildren[Random.Range(0, 4)]) as GameObject;
mobCount++;
}
}

Do not use Linq
Do not use DestroyImmediate (it will freeze and bug your game, probably)
Avoid FindGameObjectsWithTag in loops, only in initialization.
Track your enemies in an array or list
When you destroy an enemy, remove it's reference from the list
Use the list count/length to get the real actual number.

Not all gameobjects with the same script attached are respawning

I'm working on a Unity2D platformer which has blocks that break/fall when the player jumps onto them. Once the player makes contact, there is a short delay, then the block begins to slide down and shortly disappears (using SetActive(false)). If the player dies, then all "falling" blocks should respawn and return to their original positions.
I've made a level where there are two of these blocks (two completely independent gameobjects), but the problem is that when the player breaks both and then dies, when the player respawns only one of the two blocks respawns to its original position. (The other is never to be seen again.)
I think this may have something to do with how they are both attached to the same script. However I don't see how because a different gameobject is still specified in each instance of the script for each block.
Here's the code for the script attached to the block gameobjects (called breakingBlock).
public class BreakingBlock : MonoBehaviour
{
Collider2D boxCollider;
public GameObject slidingBlock;
public PlayerController player;
public float delay;
public float X;
public float startY;
public float endY;
public float speed;
void Start() // Initialises the position of the blocks
{
boxCollider = GetComponent<Collider2D>();
boxCollider.enabled = true;
slidingBlock.transform.position = new Vector2(X, startY);
player = FindObjectOfType<PlayerController>();
}
void OnCollisionEnter2D(Collision2D collision)
// Starts sliding coroutine when touched by player
{
StartCoroutine(Slide(slidingBlock, new Vector2(X, startY), new Vector2(X, endY), delay, speed));
}
public IEnumerator Slide(GameObject slidingBlock, Vector2 start, Vector2 end, float delay, float speed)
{
yield return new WaitForSeconds(delay);
while (slidingBlock.transform.position.y != end.y)
{
// Move towards end position over duration given
slidingBlock.transform.position = Vector2.MoveTowards(slidingBlock.transform.position, end, speed * Time.deltaTime);
yield return new WaitForEndOfFrame();
}
boxCollider.enabled = false;
slidingBlock.SetActive(false);
}
public void ResetSlidingBlock() // Called by another script when player dies
{
Debug.Log("Reset block");
slidingBlock.transform.position = new Vector2(X, startY);
slidingBlock.SetActive(true);
boxCollider.enabled = true;
}
}
This is the part of the other script that calls ResetSlidingBlock from the above script breakingBlock when the player dies.
void OnTriggerEnter2D(Collider2D collision)
{
if (collision.name == "Player")
{
levelManager.RespawnPlayer();
breakingBlock.ResetSlidingBlock();
}
}
Why is it that only one of the blocks is respawning when separate gameobjects are specified in the separate scripts on completely distinct gameobjects?

You have a public GameObject where only one object is assigned. Doesn't matter how many objects you assign this script to, only that GameObject that you refer to will be reset. If you have X number of GameObjects that you want to follow the same properties, you can:
Make a prefab and access the children using transform.getchild() or tags - assign them to GameObjects
ex:
GameObject objs[];
for(int i=0;i<How many u want;i++)
{
objs[i]=GameObject.Find("ParentObj").transform.GetChild(i);
//something similar to this
}
Or Simply Make public references and assign them manually.
Ex:
public GameObject slideblock1;
public GameObject slideblock2;
etc.

How to add different gravity on spawning objects?

Im working on a project that I want to create a power up effect whenever the button "Q" is pressed, I have the animation working and the character, I also have the spawning objects around my player that I want to spawn (See Figure below)
My question is how to add different gravity on each rock (spawning object).
Here is the script that I'm currently using.
/* Public Variables Declaration */
public Transform spawn_LocationForSmall;
public Transform spawn_LocationForMedium;
public Transform spawn_LocationForLarge;
public GameObject smallRock_Prefab;
public GameObject mediumRock_Prefab;
public GameObject largeRock_Prefab;
/* Private Variables Declaration */
private GameObject[] smallRocks_List;
private float posX, posY, posZ;
private bool smallCount = false;
private bool mediumCount = false;
private bool largeCount = false;
private bool small_CheckPos = false;
private bool medium_CheckPos = false;
private bool large_CheckPos = false;
void Start() {
//smallRocks_List = GameObject.FindGameObjectsWithTag("smallRock");
Create_Small_Rocks();
Create_Medium_Rocks();
Create_Large_Rocks();
}
private void Create_Small_Rocks(){
for(int i=0; i<=20; i++){
small_CheckPos = false;
posX = this.transform.position.x + Random.Range(-3.0f, 3.0f);
posY = this.transform.position.y + Random.Range(-3.0f, 3.0f);
posZ = this.transform.position.z + Random.Range(-3.0f, 3.0f);
if(posX > 3f && posY > 3f){
small_CheckPos = true;
}
if (small_CheckPos == true) {
Vector3 newPos = new Vector3(posX, posY, posZ);
GameObject createdObject = GameObject.Instantiate(smallRock_Prefab,
newPos, spawn_LocationForSmall.rotation) as GameObject;
createdObject.transform.parent = spawn_LocationForSmall.transform;
}
}
smallCount = true;
}
/* the other two functions are similar to this */

I don't really know if you can change the gravity for each individual, but you can change these things:
Mass:
In the Rigidbody component, there is a "Mass" components at the top. As in the Unity Documentation says: "Higher mass objects push lower mass objects more when colliding. Think of a big truck, hitting a small car." However, it doesn't change how fast an object falls.
Physics Material:
In the Collider components, you should see something called "Material". You can create new physics materials and edit them randomly to make the friction between the rock and the surface higher or lower, and change the bounciness of rocks that way.
Constant Force:
If you want some objects to fall faster, you might want to use this component. I personally never used this before, but it looks great for your problem. You can add a constant force to an object with this component, so if you add some downwards force on your rocks it should help them get down faster.
Please let me know if any of these helped.

Search for Particle Systems :
1) https://docs.unity3d.com/ScriptReference/ParticleSystem.html
2) https://www.youtube.com/watch?v=FEA1wTMJAR0&t=536s
3) https://www.youtube.com/watch?v=xenW67bXTgM
It allows you to upload cool effects or even prefabs as the clone objects (in this case rocks/asteroids). Its also able to control the spawning speed/ amount/ velosity/ (random)size/ physics(gravity)

adding GameObject at runtime

This may seem like a stupid question but I'm stuck with it. I have GameObjects in a list (List<GameObject>) and I want to add them on the scene runtime, prefarbly on predefined places (like placeholders or something). What would be a good way to do it? I've been searching the net but can't really find anything that would solve this. This is my code so far:
public static List<GameObject> imglist = new List<GameObject>();
private Vector3 newposition;
public static GameObject firstGO;
public GameObject frame1;//added line
void Start (){
newposition = transform.position;
firstGO = GameObject.Find ("pic1");
frame1 = GameObject.Find ("Placeholder1");//added line
//this happens when a button is pressed
imglist.Add(firstGO);
foreach(GameObject gos in imglist ){
if(gos != null){
print("List: " + gos.name);
try{
//Vector3 temp = new Vector3 (0f, 0f, -5f);
Vector3 temp = new Vector3( frame1.transform.position.x, frame1.transform.position.y, -1f);//added line
newposition = temp;
gos.transform.position += newposition;
print ("position: " + gos.transform.position);
}catch(System.NullReferenceException e){}
}
}
}
How can I place the pics (5) on the predefined spots?
//----------------
EDIT: Now I can place 1 image to a placeholder (transparent png). For some reason z-value goes all over the place so it needs to be forced to -1f but that's OK. I add the images to the list from other scenes and there can be 1-5 of them. Do I need to put the placeholders in another list or array? I'm a bit lost here.

If you've already created 5 new objects you can just do like they do here:
http://unity3d.com/learn/tutorials/modules/beginner/scripting/invoke under the InvokeScript
foreach(GameObject gos in imglist)
{
Instantiate(gos, new Vector3(0, 2, 0), Quaternion.identity);
}

I don't really understand what you're trying to do, but if I'm correct and you have a list of objects, and you know where you want to move them at runtime, just make two lists,
one containing the objects and
one containing transforms of empty game-objects in the scene placed at those predefined positions, and match them at runtime.
Populate both lists from the inspector.
public List<GameObject> imglist = new List<GameObject>();
public List<Transform> imgPositions = new List<Transform>();
void Start()
{
for(var i = 0 i < imglist.Count; ++i)
{
imglist[i].transform.position = imgPositions[i].position
}
}

The general best way is to create prefabs for your objects, passing them as a parameter and instantiate when needed (Start in your case). That's the common case, but maybe yours is slightly different.
This is an example of passing a prefabs array and to instantiate one object for each one in the array:
public GameObject prefabs[];
List<GameObject> objects = new List<GameObject>();
void Start() {
for(GameObject prefab in prefabs) {
GameObject go = Instantiate(prefab, Vector3.zero, Quaternion.identity) as GameObject; // Replace Vector3.zero by actual position
objects.Add(go); // Store objects to access them later: total enemies count, restart game, etc.
}
}
In case you need several instances for the same prefab (multiple enemies or items, for instance) just adapt code above.