coroutine

[leaden nacelle]

made a thread

so here's the code again

IEnumerator RunForTime(float duration) {
  float endTime = Time.time + duration;
  while (Time.time < endTime) {
    transform.position += Vector3.up * Time.deltaTime;
  }
}

We're missing the yield return null; line here.

That is very important.

[fleet maple]

oh right

[leaden nacelle]

Coroutines aren't really "special". I used to think they were actually running in parallel or something

They don't. They run exactly like any other method.

[fleet maple]

because it doesn't return a waitforseconds

[leaden nacelle]

The only exception is that you can yield to pause the method

and then Unity can resume it later

[leaden nacelle]

This will run forever and freeze your game.

Time.time only increases when Unity gets to the next frame

[fleet maple]

what does "yield" do?

[leaden nacelle]

yield is a C# keyword. It's used in a method that returns IEnumerator.

C# does a little bit of magic when you write a method that returns IEnumerator

you can't actually "pause" a method like this in C#

that's not a thing

but what you can do is make a little class that remembers all of the local variables

and remembers where you were

that's what the IEnumerator winds up being!

[fleet maple]

i have a question

[leaden nacelle]

An IEnumerator is a thing that can give you values when you ask for them

foreach (Transform child in transform) {
  Debug.Log("My child is named: " + child.name);
}

you use enumerators whenever you use foreach

[fleet maple]

can i for example use something like this:
startingTime=time.Time
coroutine...

endingTime =time.Time

[leaden nacelle]

When you yield return something, the enumerator produces a new value

and pauses until you ask for another value

public IEnumerator<int> GiveMeInts() {
  yield return 1;
  yield return 2;
  yield return 3;
}

foreach (var num in GiveMeInts()) {
  Debug.Log(num):
}

[fleet maple]

and in the coroutine use something like
while (endingTime-startingTime < 5f)

[leaden nacelle]

This would log

[leaden nacelle]

1
2
3

[leaden nacelle]

You would probably just write

[fleet maple]

my c# knowledge of classes is a bit bad

[leaden nacelle]

while (Time.time - startingTime)

[leaden nacelle]

i don't really know exactly what this looks like either :p

it's not too important

[fleet maple]

gotcha

[leaden nacelle]

so, vitally

if you never yield return inside that while loop

the enumerator never finishes

Time.time only goes up when you get to the next frame

If you yield return null; inside a coroutine, Unity will resume your method on the next frame

you can also do stuff like yield return new WaitForSeconds(1f); to ask Unity to resume your method in one second

[fleet maple]

void FixedUpdate()
{
if (!isInCoRoutine)
{

        StartCoroutine(MoveForSecond());
    }    
}
IEnumerator MoveForSecond()
{
    isInCoRoutine = true;
    rb.velocity = new Vector3(xSpeed, 0, 0);
    yield return new WaitForSeconds(timeCoRoutine);
    rb.velocity = Vector3.zero;
    RotateEnemy();
    isInCoRoutine =false;
}

so, to fix this, i have to use time.Time and a variable for the starting point?

[fleet maple]

gotcha

[leaden nacelle]

Actually, this looks okay to me

There's a very important difference between your code and mine

[leaden nacelle]

My code is updating the position every frame.

[leaden nacelle]

Your code is setting the rigidbody's velocity.

Once you set that velocity, Unity's physics system will move the rigidbody every physics update.

[fleet maple]

but it makes it move, then it stops, flips, wait for time and then repeat

i can send you a video

[leaden nacelle]

What do you want it to do instead?

[fleet maple]

make it move for 5 seconds, then flip and move in the opposite direction

[leaden nacelle]

is the problem that the rigidbody is slowing down and stopping?

[fleet maple]

so that it has a constant loop of movement

[leaden nacelle]

Your code should make it move for timeCoRoutine seconds, rotate, and then immediately start moving again

[fleet maple]

wait i'll send you a video

actually, it doesn't even flip

[leaden nacelle]

okay, your problem is that the rigidbody is slowing down

[fleet maple]

i guess

[leaden nacelle]

it has friction with the ground

so it stops

[fleet maple]

the friciton?

friction

so i have to create a new physics material

[leaden nacelle]

If you want to constantly set its velocity, you can write a loop like this that sets the velocity every frame

[fleet maple]

can't i make the friction 0?

[leaden nacelle]

Sure, that would work

[fleet maple]

nothing changed btw

so i'll have to set it's velocity with the script

[leaden nacelle]

it also may have drag

[fleet maple]

void FixedUpdate()
{
if (!isInCoRoutine)
{

        StartCoroutine(MoveForSecond());
    }    
}
IEnumerator MoveForSecond()
{
    while (Time.time < startingTime + timeCoRoutine)
    {
        startingTime = Time.time
        isInCoRoutine = true;
        rb.velocity = Vector3.zero;
        RotateEnemy();
        isInCoRoutine = false;
        yield return null;

    }
}

can this work?

i forgot to set startingTime

does it now?

no wait, stuff that should be outside the while loop are inside it

[leaden nacelle]

yes, the loop should only contain the thing that makes the enemy move

you're also setting the enemy velocity to zero right now

[fleet maple]

void FixedUpdate()
{
if (!isInCoRoutine)
{

        StartCoroutine(MoveForSecond());
    }    
}
IEnumerator MoveForSecond()
{
    isInCoRoutine = true;
    startingTime = Time.time;
    while (Time.time < startingTime + timeCoRoutine)
    {
        rb.velocity = new Vector3(xSpeed, 0, 0);
    }
    RotateEnemy();
    isInCoRoutine = false;
    yield return null;
}
void RotateEnemy()
{
    transform.Rotate(0,180,0);
}

}

fixed it (i hope so)

[leaden nacelle]

Looks reasonable. You're just missing the thing to set the velocity to 0 at the end

but if you immediately set the velocity again, I guess that doesn't matter

also, this wouldn't make the enemy move back and forth

[fleet maple]

i removed it bc i didn't get what use it had

[leaden nacelle]

unless you're changing xSpeed somewhere else

[fleet maple]

why? shouldn't the enemy flip?

[leaden nacelle]

the velocity of a rigidbody is in world space

[fleet maple]

people told me that by flipping it, it works

[leaden nacelle]

it doesn't matter what the rotation of the object is

the enemy will always move in the world +X direction

you could use rb.velocity = transform.forward to make the enemy move in whatever direction is "forward" for the enemy

[fleet maple]

ok

[leaden nacelle]

the blue arrow is forward here

You might want transform.right instead, if the red arrow is the way the enemy is supposed to move

[fleet maple]

they are moving in the x axis

the game is taking 4 minutes to load, is it normal?

it has always taken 10 seconds or so

[leaden nacelle]

if it gets stuck, you can kill the editor and reopen it

[fleet maple]

i did it, but i was afraid i would have lost the code, so i copied it

[leaden nacelle]

you can only lose scene data when you kill the editor

(if you haven't saved)

[fleet maple]

i didnt lose anything

it's still stuck

i wonder wether that's something related to the code

[leaden nacelle]

by "stuck" do you mean the editor is frozen after trying to play the game?

[leaden nacelle]

        while (Time.time < startingTime + timeCoRoutine)
        {
            rb.velocity = new Vector3(xSpeed, 0, 0);
        }

[fleet maple]

it's trying to load it

[leaden nacelle]

what's wrong here?

[fleet maple]

Time.time doesn't change during the loop?

[leaden nacelle]

right, because you forgot something

[fleet maple]

yield return null

yield return Time.time?

no

it has to return something

idk

😭

it's so complex

[leaden nacelle]

remember that yield return null tells Unity to resume the method one frame later

and you want to do this every frame

[fleet maple]

and how do i do it?

@leaden nacelle

[leaden nacelle]

        while (Time.time < startingTime + timeCoRoutine)
        {
            rb.velocity = new Vector3(xSpeed, 0, 0);
            yield return null;
        }

that's all you need

you set the velocity, then you pause the coroutine until the next frame

[fleet maple]

but you said that yield return null skips a frame

[leaden nacelle]

you do that over and over until Time.time is large enough

no, it does not skip a frame

if I'm in frame 6, the next frame is frame 7

[fleet maple]

and how does the coroutine stop?

after the while loop the isInCoRoutine is false, so it can start another coroutine, does that mean the coroutine is ended?

[leaden nacelle]

the coroutine ends when the method ends

[leaden nacelle]

once you leave the while loop, your method does some more work and then exits

[fleet maple]

ok

i have still the same issue as yesterday btw

the enemy gameObject doesn't flip

i tried with transform.Rotate, with rb.moverotate and rb.rotate but idk i don't get it

oh wait

no, nothing

to flip it i need to rotate it on the y axis, that's what i'm doing

[leaden nacelle]

you need to set the rotation of the rigidbody

rb.rotation *= Quaterion.AngleAxis(180, Vector3.up);

this will work

AngleAxis creates a rotation by that many degrees around a specific axis

Multiplying two quaternions combines their rotations

[fleet maple]

it cannot translate by unityengine.quaternions to system.numerics.quaternion

whatever that means

[leaden nacelle]

you have a bad using directive up top

there's a "Quaternion" class in System.Numerics

but this has nothing to do with Unity's Quaternion

get rid of using System.Numerics;

[fleet maple]

but there isn't a system.numerics there

[leaden nacelle]

show me your entire script

[fleet maple]

oh wait

yeah

done

so this should work?

maybe i got the issue

it flips, but it still goes on that direction

maybe during the coroutine, before flipping it, making its speed *= -1

[leaden nacelle]

are you still using rb.velocity = new Vector3(xSpeed, 0, 0);

if so, change that

[fleet maple]

rb.velocity = Vector3.right*xSpeed;

[leaden nacelle]

that's always going to go right

[fleet maple]

this is what i am using

[leaden nacelle]

Vector3.right is a constant. It's a vector pointing in the +X direction

[fleet maple]

oh and i have to rotate the object

[leaden nacelle]

transform.right varies. It's whatever direction is "right" for the transform

No, you don't need to do any more rotating. You just need to use the correct direction.

[fleet maple]

by using transform.forward it goes on the z

[leaden nacelle]

rb.velocity = transform.right * xSpeed; would make the enemy move in whatever direction is "right" for it

[fleet maple]

i'm using Vector3.forward

that's the problem

[leaden nacelle]

you mean transform.forward ?

[fleet maple]

nope

[leaden nacelle]

Vector3.forward will always move you into the screen

[fleet maple]

i mistook

[leaden nacelle]

personally, I would rotate the enemy 90 degrees around the Y axis, so that its forward vector is pointing in the direction it wants to move

[fleet maple]

now i put there transform.forward

[leaden nacelle]

the blue arrow here

make sure you're on "local" mode when checking this

[fleet maple]

i am on local

[leaden nacelle]

okay, so select the enemy and rotate it so that its blue arrow points the way it should move

then set rb.velocity = transform.forward * speed;

[fleet maple]

rb.velocity = transform.forward*xSpeed;