C# Rotation Not Working Properly

Unity Engine
1

Hi, I am trying to rotate a 2D object one way, then another in a continuous loop.

public class GearChangeSpin : MonoBehaviour {
    void Update() {
        StartCoroutine (spin());
    }

    IEnumerator spin() {
        transform.Rotate(0, 0, -0.5f);
        yield return new WaitForSeconds(1.5f);
        StartCoroutine (spinOtherWay());
    }

    IEnumerator spinOtherWay() {
        transform.Rotate(0, 0, 0.5f);
        yield return new WaitForSeconds (1.5f);
        StartCoroutine (spin());
    }
}

What happens when I start the scene is that for 1.5 seconds my sprite will rotate the correct way, then after calling spinOtherWay() it tries to do both spin() and spinOtherWay() at once - jamming the movement.

Is there a way to completely halt spin() and spinOtherWay() as I do not want their functions to continue until otherwise stated? Does the problem stem from using void Update() to start off the process? I tried change void Update() to void Start() and there was no movement whatsoever.

Thanks,

Kittik

2

Have you ever heard of sine waves? I used a sine wave to make a wobbling platform that basically rotated so far one way, then the same in the other direction in a continuous loop. I can dig up the script if it would help. It’s much shorter than what you are doing. I think it was only a few lines.

3

The problem is not your rotate, it is your use of coroutines. You are starting a coroutine every update and again in every coroutine. meaning that after a few seconds you will have hundreds of coroutines running(60fps*10sec == 600 update calls).

You will only want to start to coroutine once. In Start for example. You will also need a few loops in your coroutines for it to work as you want.

1 Like
4

I also noticed that. You definitely don’t want to start your coroutine in the update method.

5

I have not heard of sine waves. Any further help would be much appreciated. Yes, I too know of the issue of having loads of update calls, I was making it this way simply because I didn’t know how to otherwise. Will look up sine waves now!

1 Like
6 
if(wobbleSpeed != 0 && alwaysWobble ){
            _rotationTimer += Time.deltaTime;
            float phase = Mathf.Sin(_rotationTimer / (1 / wobbleSpeed));
            transform.localRotation = Quaternion.Euler( new Vector3(0, 0,  phase * wobbleAngle));
        }

Just modify the variables to suit your needs. You’ll want a float to store the timer. A float to store the angle in degrees, and a float to store the speed at which to rotate. Oh, and just run it in the normal update and attach the script to the object you wish to rotate.

7

you don’t need sine waves for this. You just need to fix your coroutines.

What you can do is this: apply rotation in Update and set the rotation direction in a coroutine. Then the coroutine code would just be:

while(enabled)
{
    rotSpeed = 0.5f;
    yield return new WaitForSeconds(1.5f);
    rotSpeed = -0.5f;
    yield return new WaitForSeconds(1.5f);
}
1 Like
8

This would also work. Sine waves are just how I would do it. There’s more than one way to skin a cat.

9

Hey, I am trying to implement the code and am having trouble.

public class GearChangeSpin : MonoBehaviour {

    public float rotSpeed;

    void Update() {
        //StartCoroutine (spin());
        transform.Rotate(0, 0, rotSpeed);
        StartCoroutine (spin());
    }

    IEnumerator spin() {
        while (enabled) {
            rotSpeed = 0.5f;
            yield return new WaitForSeconds (1.5f);
            rotSpeed = -0.5f;
            yield return new WaitForSeconds (1.5f);
        }
    }

What am I doing that is causing a problem? Should I have declared an arbitrary float in the constructor or something? Thanks for the help thus far.

10 
public class GearChangeSpin : MonoBehaviour {

    public float rotSpeed;
    private bool isTurning;

    void Update() {
        transform.Rotate(0, 0, rotSpeed);
        StartCoroutine (spin());
    }

    IEnumerator spin() {
        while (isTurning == false) {
            rotSpeed = 0.5f;
            yield return new WaitForSeconds (1.5f);
            isTurning = true;
        }
        while (isTurning == true) {
            rotSpeed = -0.5f;
            yield return new WaitForSeconds (1.5f);
            isTurning = false;
        }
    }

It all works now! Thanks for the help.

11

… You are still starting your coroutine in update. Update is called every frame(so at 60fps 60 times a second). Meaning that you will start extra coroutines 60 times a second. meaning that after a short while it will get very very slow because you will have 1000s of coroutines running. You need to start it only once!