2D Wind Indicator

Getting Started
1

Hi, I am using a arrow to indicate a Vector2 wind direction which I would like to rotate in the UI to point in the direction of the wind.
How would I rotate a Image of a arrow to point in the direction of the wind?
I have got as far as the code below but this is wrong.

public void GetWindDirection()
    {
        windDir = new Vector2(Random.Range(0f, 360f), Random.Range(0f, 360f));
        windStrength = Random.Range(-0f, 0.1f) / 100;

        Debug.Log("Wind Direction: " + windDir + " Wind Strength: " + windStrength);
    }

//ADD WIND HERE
            myRb.AddForce(windDir * windStrength);

public void UpdateWindIndicator()
    {
        Vector2 windDir = gameMan.GetWindDirection();
        //windIndicator.transform.rotation = windDir;
    }
2

If your wind direction (and strength) is represented as a Vector2, then you convert that to an angle using Mathf.Atan2, e.g.:

float angle = Mathf.Atan2(windDir.y, windDir.x) * Mathf.Rad2Deg;
transform.localEulerAngles = new Vector3(0, 0, angle);

Depending on which way your display is set up, you might want to rotate around Y instead of Z in the second line above. Also this is off the top of my head, so please double-check the syntax. :slight_smile:

3

Thankyou Joe, the Image now rotates but there is still a issue with the windDir, I dont think I am calculating the wind properly with the first line of code at the top as the ball behaves oddly when force is applied.
I`m trying get get a random direction and apply it to the Rb if you can see the error.
Many thanks.

4

Yes, that first line doesn’t make much sense. You’re computing a wind vector that is somewhere in the giant square area between [-360,360] and [360,360]. Perhaps you meant to use Random.onUnitCircle instead?

Or, maybe you want to keep your windDir as just an angle, not a Vector2. Then you wouldn’t have to use Atan2 to recover the angle when you need it later. In that case declare it as Vector2 and just do windDir = Random.Range(-360f, 360f).

5

Thanks Joe, if windDir is now a float how do I apply it to the rb with myRb.AddForce(dir, str) if Add force is asking for a vector2 for the first parameter?
Many thanks.

6

Ah, in that case you would need to find the corresponding vector, taking into account both the angle and the strength. Trigonometry is your friend here:

float radians = windDir * Mathf.Deg2Rad;
Vector2 windVec = new Vector2(windStrength * Mathf.Cos(radians), windStrength * Mathf.Sin(radians));
7

Thanks Joe, ive gone for the simplest method with a float, but with this code the wind indicator doesnt seem to point in the right direction. If you can see the error. Many thanks.

public void UpdateWindIndicator()
    {
        //get winddirection
        float windDirection = gameman.GetWindDirection();
        float angle = windDirection * Mathf.Rad2Deg;
        windIndicator.transform.localEulerAngles = new Vector3(0, 0, angle);
    }
8

Not from this, no. I see from line 5 that this code assumes GetWindDirection() is going to return a wind direction in radians (rather than degrees). Is that in fact the case?

9

The wind direction is a float Joe, thanks.
float windDirection = random.range(-360, 360);
Wind Indicator point in direction of wind, thanks.

10

Hi Joe, can you tell me what line 5 should be if windDir is a float,
float angle = windDirection * Mathf.?
Many thanks.