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Spawning hundreds of rigidbody2d enemies that follow player while keeping up performance

So I'm creating a 2D top-down endless shooter game and need enemies to spawn faster as time goes on. The enemies health also scales with the player level. I'm using Unity 2020.1.4.
The problem I have is that at a certain point the framerate just drops cause of the amount of rigidbodies in the scene at the point in time.
Is there any way I can redo this or refine it to make it less resource intensive?
Code:
public class EnemySpawn : MonoBehaviour
{
public GameObject[] enemies, bossEnemy;
float bossTimer;
public float timeForBoss, bossTime, startTimeForBoss = 60f;
public float spawnRadius = 7f, time, defaultTime = 3f;
public float fasterSpawnIncrements, spawnIncTimer, spawnIncTimerHolder;
public bool timerDecreased = false;
// Start is called before the first frame update
void Start()
{
time = defaultTime;
spawnIncTimerHolder = spawnIncTimer; //Set timers for making enemies spawn faster over time
StartCoroutine(SpawnAnEnemy());
bossTimer = startTimeForBoss; //Set timers for making bosses spawn faster over time
timeForBoss = 60f;
}
void FixedUpdate()
{
spawnIncTimerHolder -= Time.deltaTime; //Decrease timer for enemies
while (spawnIncTimerHolder <= 0)
{
time *= fasterSpawnIncrements; //Decrease time between enemy spawns
spawnIncTimerHolder = spawnIncTimer;
}
bossTimer -= Time.deltaTime;
if (bossTimer <= 0)
{
StartCoroutine(SpawnABoss());
if (timeForBoss > 8)
{
timeForBoss -= 4f;
timerDecreased = true;
}
if (timeForBoss <= 8 && timeForBoss > 3)
{
timeForBoss -= 2f;
timerDecreased = true;
}
bossTimer = timeForBoss;
}
}
IEnumerator SpawnAnEnemy()
{
Vector2 spawnPos = GameObject.Find("Player").transform.position;
spawnPos += Random.insideUnitCircle.normalized * spawnRadius; //Set allowable spawn point area around the player
Instantiate(enemies[Random.Range(0, enemies.Length)], spawnPos, Quaternion.identity); //Spawn enemy
yield return new WaitForSeconds(time);
StartCoroutine(SpawnAnEnemy());
}
IEnumerator SpawnABoss()
{
Vector2 spawnPos = GameObject.Find("Player").transform.position;
spawnPos += Random.insideUnitCircle.normalized * spawnRadius; //Set allowable spawn point area for bosses around the player
Instantiate(bossEnemy[Random.Range(0, enemies.Length)], spawnPos, Quaternion.identity); //Spawn boss
yield return new WaitForSeconds(bossTime);
//StartCoroutine(SpawnABoss());
}
}
I know it's not the prettiest code but it works, kinda. I really need this optimised cause my computer is a potato and its getting more and more difficult to playtest every time I want to add a new feature.

Use Window->Profiler to see which steps/scripts actually take up most time.
Object Pooling. Basically, instead of "Instantiate" & "Destroy" you keep filling your pool with Instantiate, but disable instead of destroy. Then, instead of instantiate, you just enable objects and update position, reset health etc. This improves memory handling, garbage collection etc. You can look for a pooling solution or just use an Array/List and manage it yourself.
DOTS/ECS. Unity can handle a TON of entities when you use the Data oriented / entitiy component system. That is a bit different way to program and handle your data.
Unity supports Havoc Physics when using DOTS/ECS. That may help increase performance with your Rigidbodies.

Moving Prefabs, Unity Spawner, Move Position

I have one problem. I want my prefabs to spawn every time my player picks them up. I did research on Google and YouTube and I tried to use the random function and instantiate. I don't know how to use them. I wrote this code I saw on YouTube and my prefab Sphere moves like 1cm to z position. I want to every time when I pick up object or my player go to spawn more of this on the z position. How do I do this?
My smaller script:
public GameObject Sphere;
public float zrange;
// Use this for initialization
void Start () {
RandomPosition();
}
void RandomPosition()
{
zrange = Random.Range(0f, 2f);
this.transform.position = new Vector3(0, 0, zrange);
}

You achieve that by not messing with the x and y values (your code sets them both to 0).
Vector3 p = transform.position;
p.z = zrange;
transform.position = p;
This assumes that your code to instantiate the object is already correctly placing the object. If not, more information is needed.

What code do I need for my Unity character to shoot the bullet correctly?

I am not new to programming, but I am new to C#. I am experienced in Python, Java, and HTML. My game is 2D I have a game where my character currently has to touch the enemy to kill it. Now I added code for shooting a bullet to kill the enemy. I also want the bullet to be shot if the spacebar is pressed. The character is supposed to a shoot bullet in either direction. I have taken my code from an example my professor gave me which was originally Javascript and I converted it to C#. Unity no longer supports Javascript. The example code he gave me was basically a rocket shooting as many bullets as I clicked (clicking the mouse shoots bullets) to eliminate an enemy, however the rocket in that example does not move. In my game, the character moves, so the bullet has to get the position of the character. What is the correct code for getting the character position and shooting a bullet correctly?
I tested my game with my current code. The bullet is being spit out of nowhere (from the bottom of my background wallpaper [smack in the middle of the bottom] to a little below the wallpaper). Not even from the character...
Also, I added the Hit class script to my Bullet category in Unity.
Complete Camera Controller (no issues here at all)
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;
}
}
Complete Player Control Class (If you read the comments in the code that say the "BULLET CODE", that's new code I have placed in the game for the bullets.
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.
Rigidbody2D bullet;
float speed2 = 30f; //BULLET CODE
// 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");
Rigidbody2D bulletInstance; //BULLET CODE
//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(Input.GetKeyDown(KeyCode.Space)&& Hit.hit == false) //BULLET CODE IN HERE
{
// ... instantiate the bullet facing right and set it's velocity to the right.
bulletInstance = Instantiate(bullet, transform.position, Quaternion.Euler(new Vector3(0,0,0)));
bulletInstance.velocity = new Vector2(speed2, 0);
bulletInstance.name = "Bullet";
}
}
//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!";
}
}
Hit code. All code in this class is made for the bullet.
using UnityEngine;
using System.Collections;
public class Hit : MonoBehaviour
{
GameObject[] gameObjects;
public static bool hit = false;
void Removal ()
{
gameObjects = GameObject.FindGameObjectsWithTag("Bullet");
for(var i= 0 ; i < gameObjects.Length ; i ++)
Destroy(gameObjects[i]);
}
void OnCollisionEnter2D ( Collision2D other )
{
if(other.gameObject.name=="Bullet")
{
Removal();
Destroy(gameObject);
hit = true;
}
}
}

I see several issues with the code you wrote. as #Kyle Delaney suggested, I'd also highly recommend you check out the Unity Learn website, and go through several tutorials before moving through. I've highlighted a few issues below that may help solve your problem, but you could really benefit from changing your approach in the first place to avoid many of these issues. See below.
In your camera controller class, why not make the offset public so you can set it yourself in the inspector>
In Player controller class:
changed:
if (Input.GetKeyDown(KeyCode.Space)) //Shoot bullet
{
// ... instantiate the bullet facing right and set it's velocity to the right.
Rigidbody2D bulletRB = Instantiate(bullet, transform.position, transform.rotation);
bulletRB.AddForce(new Vector2(speed2,0), ForceMode2D.Impulse);
}
On a click, this instantiates the bullet prefab and sets its transform to copy the position and rotation of the player. It then adds a force to it to the right. You should avoid setting the velocity manually with rigidbodies, this can cause unwanted behaviour. Use the Addforce/addTorque methods instead. The ForceMode says to ignore its mass and set its velocity.
Then delete your Hit class, and replace with this Bullet class, which you drag onto the bullet prefab. Your player shouldn't be in charge of checking for bullet hits. that's the bullet's job. The player just launches the bullets and then the bullets do what bullets do. this just checks to see if the bullet hit anything, if so it destroys it. You can make this more complicated if you want. I would recommend using layers to determine which layers the bullet checks collisions with. You probably don't want bullets destroying your terrain. and you definitely don't want bullets destroying the player itself!
public class Bullet : MonoBehaviour
{
private void OnCollisionEnter2D(Collision2D collision)
{
Destroy(collision.gameObject);
Destroy(this.gameObject);
}
}
Also you shouldn't need to set the name of the bullet, since your prefab bullet should already be named "bullet".
I hope this gets you started in the right direction. But based on your code, I HIGHLY recommend you work through the tutorials before continuing with any projects. The unity staff that make them are super helpful and the tutorials start off really simple but get really complicated fast, so you actually come away learning a ton!

Perhaps the problem has to do with the player's parent transform. You could try something like this to make sure the bullet has the right parent:
bulletInstance = Instantiate(bullet);
bulletInstance.transform.parent = transform.parent;
bulletInstance.transform.position = transform.position;
bulletInstance.velocity = new Vector2(speed2, 0);
bulletInstance.name = "Bullet";
If that doesn't work it may be worthwhile to check the player's Rect Transform to see where the anchors and pivot are. Perhaps the player's actual "position" coordinates aren't where you think they are.
Have you done the Space Shooter tutorial? It has a segment about shooting bullets.

How to have a powerup have a slight chance of spawning when killing an enemy?

so we have a class assignment and pretty much we are doing the Survival Shooter project from the Unity tutorials. I've managed to make health packs and little boxes that give you speed when you pick them up, but now I want the power-ups to have a slight chance of dropping when enemies die. Can someone help me out? I'm not really asking for entire code, I have some down below:
public float percentDrop = 50f;
public GameObject HealthPack;
void Awake()
{
HealthPack = GetComponent<GameObject>();
}
public void TakeDamage (int amount, Vector3 hitPoint) { if(isDead) return;
enemyAudio.Play ();
currentHealth -= amount;
hitParticles.transform.position = hitPoint;
hitParticles.Play();
if(currentHealth <= 0)
{
Death ();
}
}
void Death ()
{
isDead = true;
capsuleCollider.isTrigger = true;
anim.SetTrigger ("Dead");
enemyAudio.clip = deathClip;
enemyAudio.Play ();
var randChance = Random.Range(0f, 100f);
if (randChance < percentDrop)
{
//GameObject.Healthpack.setActice(true);
}
}
I'm not too sure how to make the Game Object spawn when they die, can someone help me out?

Create a "Health Pack" prefab from the editor. If you need more information about prefabs, the information is out there on the web. To create a prefab, simply drag and drop a GameObject from the scene to your project. Its name in the scene will become blue. You can delete it from the scene and it will still be in the project.
Drag the prefab from the project to the HealthPack slot in the inspector of your ennemy. The ennemy will now have a reference to the prefab.
When you want to create a new health pack, you can use the Object.Instantiate static method as specified by rutter. Here is the official doc. When you instantiate your new Health Pack, I guess you want it to appear where the ennemy is, wich means you'll want to use one of the method's overloads which takes a Vector3D position as a parameter, which will most likely be transform.position. Since those methods also ask for a Quaternion, just pass in the Quaternion.identity constant.
This is how your code could look:
if (randChance < percentDrop)
{
Object.Instantiate(HealthPack, transform.position, Quaternion.identity);
}
Another problem, as mentioned in my comment, is the Awake function: HealthPack = GetComponent<GameObject>();.
The HealthPack prefab should be assigned to the ennemy from the inspector. That line in the Awake function will assign your ennemy's GameObject component to HealthPack, which is not desirable in the current context.
I hope this helps!

Make GameObject “attach” properly?

This script makes a cube "stick" to whatever it collided with. The problem is that when it's going at relatively high or medium speeds (or when the device itself is slow), the cube tends to "get a bit inside" what it collided with and then stick to it. What changes do I have to make to fix this?
In order for this script to work, one GameObject must have bool _sticksToObjects = true; and the other bool _sticksToObjects = false;
I have tried turning the Rigidbody's Collision Detection mode to either Continuous or Continuous Dynamic
I think my script depends on frame rate. That may be where the problem lies.
Normal "Attach":
Abnormal "Attach":
Rigidbody _rigidBody;
Transform _meshTransform;
bool _sticksToObjects = true;
public Transform _stuckTo = null;
protected Vector3 _offset = Vector3.zero;
void Awake()
{
GameObject CubeMesh = GameObject.FindWithTag ("CubeMesh");
GameObject Cube = GameObject.FindWithTag ("Cube");
_rigidBody = Cube.GetComponent<Rigidbody> ();
_meshTransform = CubeMesh.GetComponent<Transform> ();
}
void Update()
{
if (_stuckTo != null)
{
transform.position = _stuckTo.position - _offset;
}
}
void OnCollisionEnter(Collision collision)
{
if (!_sticksToObjects) {
return;
}
_rigidBody.isKinematic = true;
// Get the approximate collision point and normal, as there
// may be multipled collision points
Vector3 contactPoint = Vector3.zero;
Vector3 contactNormal = Vector3.zero;
for (int i = 0; i < collision.contacts.Length; i++) {
contactPoint += collision.contacts [i].point;
contactNormal += collision.contacts [i].normal;
}
// Get the final, approximate, point and normal of collision
contactPoint /= collision.contacts.Length;
contactNormal /= collision.contacts.Length;
// Move object to the collision point
// This acts as setting the pivot point of the cube mesh to the collision point
transform.position = contactPoint;
// Adjust the local position of the cube so it is flush with the pivot point
Vector3 meshLocalPosition = Vector3.zero;
// Move the child so the side is at the collision point.
// A x local position of 0 means the child is centered on the parent,
// a value of 0.5 means it's to the right, and a value of -0.5 means it to the left
meshLocalPosition.x = (0.5f * contactNormal.x);
_meshTransform.localPosition = meshLocalPosition;
if (_stuckTo == null || _stuckTo != collision.gameObject.transform) {
_offset = collision.gameObject.transform.position - transform.position;
}
_stuckTo = collision.gameObject.transform;
}
Here are some screenshots of the Unity editor:

This is a well-known category of problem in game engineering and you'll be pleased to know the solution is relatively simple. You'll be pleased to hear there are similar, but much more complicated, problems that are actually solved in the same way. I'll try to explain.
Now here's the thing. It's quite often that the following question comes up...
So I'm working on GTA. I have a humanoid, H, running around. She approaches vehicle V. She opens the door and gets in and drives off. After that everything goes to hell in Mecanim and all the code stops working. What to do?
Surprisingly, the way that is done in games is:
Surprisingly: you actually swap to totally different models at that point!!!!!
You have H and V in the game. But then you have an animation (say) for H climbing in to V. But then, you literally destroy the game objects of H and V, and you Instantiate (or just awake) a new, totally different, game object, which is D ("a car being driven around by a lady").
(If you think about it, you can see that when you do this, you carefully adjust all the stuff in D, so that it matches what was "just then happening" in the frame, in relation to both H and V. So for example, literally, you copy the transform, twist etc of the car V, to the new car-inside-D, if lady H has the SmearedMakeupEffect, you put the same SmearedMakeupEffect on the lady-within-D, you position all the bones identically, and so on.)
Another simple example of this is, you often get people asking, "my character C gets killed and I want it to become a ragdoll, how to?" In fact you just swap to a totally new game object you have all set up for that passage of the game. Indeed, if you have a character A ("Arnie") in a game, it's normal that you have 4 or 5 "different As" sitting offside the stage, so, there's "ragdoll A", "A who can dance" "A with weapon". And indeed many of these are combos, you know "A on the horse" "A in the car" and so on.
So interestingly, the "real" solution here is,
once they become a new connected thing, destroy them both and swap to a new game object altogether!
if you have made games "until you are blue in the face" from making games, this is just what you would do as a matter of course. Even though its' a simple situation, it's just easier in the long run. After all, consider all the stuff you have to do when this happens:
make hitting object child of the other
turn off physics on the child
change the way your physics works for the whole thing
turn off or change the collider on the hitting object, perhaps making it part of the overall object
you'll likely have some sort of new "separation" physics where it can be knocked-off - you'd have to turn all that on
likely change minor issues like sound effects, colors etc
As you can see it's a huge chore doing all this stuff, and indeed it's one of those things it's just "easier to do properly" and change to a new model.
All that being said, I know you want a Quick Script Solution you can Paste In :) Here it is...
Step 0, You'll create "YourScript" which goes on the "main" cube. it will "catch" another cube moving around.
YourScript will look basically like this ...
[System.NonSerialized] public bool isConnectedNow;
void OnCollisionEnter(Collision collision)
GameObject theThingWeCaught = collision.gameObject
Debug.Log("We caught this thing .. " + theThingWeCaught.name)
// make it a child of us......
theThingWeCaught.transform.parent = transform
theThingWeCaught ... set kinematic
theThingWeCaught ... probably disable the rigidbody
theThingWeCaught ... probably disable the collider
isConnectedNow = true;
That's really all you have to do.
Step 1, YOUR script must have a public bool like this
[System.NonSerialized] public bool isConnectedNow;
Step 2, Here's MyScript which goes on the hitting cube, first we'll unit-test that your isConnectedNow bool is working
public Class MyScript:MonoBehaviour // attach to the "child" cube
{
public float correctXDistance;
public float correctYDistance;
public Transform bigCube;
public YourScript yourScript;
void Update()
{
string message = yourScript.isConnectedNow ? "free" : "stuck";
Debug.Log("I am " + message);
}
}
attach, debug, and run. Make the little cube stick and unstick from the big cube .. Watch the console. it works? So add this to MyScript
private void DistanceCorrectionX()
{
float xDistance = bigCube.position.x - transform.position.x;
float xSign = Mathf.Sign(xDistance);
float xDelta = Mathf.Abs(xDistance);
float closenessPercentage = (xDelta/correctXDistance)*100f;
if ( closenessPercentage<90f || closenessPercentage>110f)
{
// they are not close enough to quantize on this axis
// this comes in to play when you have multiple axes
return; // do nothing.
}
float xShouldBe = bigCube.position.x + xSign * correctXDistance;
Vector3 p = transform;
p.x = xShouldBe; // be careful it's .y, .z etc for other axes
transform.position = p;
}
for now call that in Update() in MyScript like this
void Update()
{
Debug.Log("I am " yourScript.isConnectedNow ? "free" : "stuck");
if (yourScript.isConnectedNow) DistanceCorrectionX();
}
Now actually Play and make it stick. Now, since it's running in Update simply while Play look at the Inspector for MyScript and adjust the value of correctXDistance to get the exact look you want. When yo have decided on a value, unPlay and put that in as the final value you wish.
Next, in DistanceCorrectionX simply duplicate all the code and do it again for the Y axis DistanceCorrectionX. If you also do Z, do that.
Finally. Note you will have a lot of messy code, like this...
void Update()
{
// handle all the DistanceCorrectionX etc as seen above.
if (yourScript.isConnectedNow)
{
.. turn off the collider on me
}
else
{
.. turn on the collider on me
}
}
and so on, there's "many little things" you'll need to do.
Don't forget also, overwhelmingly you may want to make the hitting object a child of the big object, depending on your situation. (Then of course they would move around together as a unit.)
Note that in the positioning code above I just showed it as position, not local position, for pedagogic clarity. If you want to do them flinging around, and spinning and so on, you'd make the hitting object a child of the other and you would use localPosition in the same way. Enjoy.

One possible way that comes to my mind is:
Inside of the "collision enter" check the distance between these objects and move the one that should stick to the other one a bit away.
As you see in the picture the distance between A and B should be equal to the sum of the widths divided by 2 (with a small threshold of course).
If the distance is less than the sum of the widths / 2 then you have an abnormal "attach" and you have to move one of the objects away. Its not really difficult to accomplish that.