Unity2D rotation issue

Question

I am trying to add a parachute in my game, and I need it to rotate 45 degrees right and then 45 degrees left and keep alternating, diagram of how i need to work below

The code that i am using is as follows, however it only works on 1 side then doesn't go back.

        if (maxRotation <= transform.rotation.eulerAngles.z)
        {
            rotatingRight = false;
        }else if(minRotation <= transform.rotation.eulerAngles.z)
        {
            rotatingRight = true;
        }

        transform.Translate(Vector2.down * fallSpeed * Time.deltaTime);

        if (rotatingRight)
        {
            transform.Rotate(Vector3.forward * 45 * Time.deltaTime);
        }
        else
        {
            transform.Rotate(Vector3.forward * -45 * Time.deltaTime);
        }

Change to `else if(minRotation >= transform.rotation.eulerAngles.z)`. Note the `>=` vs your `<=`. — 3Dave, Feb 04 '20 at 18:55

Ruzihm · Accepted Answer · 2020-02-05T15:58:02.723

As 3Dave said in the comments, it's mostly that you should rotating right when minRotation is greater than or equal to eulerAngles.

if (maxRotation <= transform.rotation.eulerAngles.z)
{
    rotatingRight = false;
} else if (transform.rotation.eulerAngles.z <= minRotation)
{
    rotatingRight = true;
}

transform.Translate(Vector2.down * fallSpeed * Time.deltaTime);

if (rotatingRight)
{
    transform.Rotate(Vector3.forward * 45 * Time.deltaTime);
}
else
{
    transform.Rotate(Vector3.forward * -45 * Time.deltaTime);
}

I realize now that the previous version of this answer was needlessly convoluted but I can't delete it now that it's accepted. The problem was simply caused by a typo.

Jonathan Mathieu · Answer 2 · 2020-02-05T17:50:16.603

Your code can be simplified quite a lot. You actually wouldn't need a boolean to see if you're going right. Just do it in the first if, no need for a second one. Also there's a good chance you are going to reduce the amount of error that can slip in like here where your boolean isn't always what you think it is.

float rotationValue = 45;

if(transform.rotation.eulerAngles.z >= maxRotation)
{
    rotationValue = -45;
}
else if(transform.rotation.eulerAngles.z <= minRotation)
{
    rotationValue = -45;
}

transform.Translate(Vector2.down * fallSpeed * Time.deltaTime);


transform.Rotate(Vector3.forward, rotationValue * Time.deltaTime);

Now this will always rotate right when it is between the min and max rotations — Ruzihm, Feb 05 '20 at 17:46

score -1 · Answer 3 · answered Feb 04 '20 at 19:43

-1

I was able to solve it by doing this

        if (maxRotation == Math.Round(transform.rotation.eulerAngles.z))
        {
            rotatingRight = false;
        }else if(minRotation == Math.Round(transform.rotation.eulerAngles.z))
        {
            rotatingRight = true;
        }

        transform.Translate(Vector2.down * fallSpeed * Time.deltaTime);

        if (rotatingRight)
        {
            transform.Rotate(Vector3.forward * rotationSpeed * Time.deltaTime);
        }
        else
        {
            transform.Rotate(Vector3.back * rotationSpeed * Time.deltaTime);
        }

answered Feb 04 '20 at 19:43

Matthew Scicluna

87
7

1

please don't do this - if a lag spike occurs at a bad time, causing `Time.deltaTime` to be huge, you might rotate the rotation beyond `minRotation` and `maxRotation`. you don't guarantee that it won't go above `maxRotation` or below `minRotation`, so it would then continue to rotate in one direction forever. – Ruzihm Feb 04 '20 at 20:30
Ah I see, do you by any chance have a solution on how i can achieve this in a proper way? – Matthew Scicluna Feb 04 '20 at 20:35
My answer is fine, but one of the best methods would be to use something like Mathf.PingPong to get the z eulerAngle you need that frame – Ruzihm Feb 04 '20 at 21:04

Unity2D rotation issue

3 Answers3