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# Rotate a Vector3 direction

How can i rotate a Vector3 direction 45 degrees along the y axis? So a Vector3(1,0,0) for example, would become Vector3(0.5,0,0.5).

And i cant use Transform.RotateAround, or any other Transform methos. As i am not applying this Vector3 directly to a object.

**Answer** by Jessy
·
Feb 08, 2011 at 08:04 PM

http://unity3d.com/support/documentation/ScriptReference/Quaternion.AngleAxis.html

```
vector = Quaternion.AngleAxis(-45, Vector3.up) * vector;
```

That's a general case. For rotation around a world axis, it's faster/easier:

```
vector = Quaternion.Euler(0, -45, 0) * vector;
```

For (1,0,0), this results in (sqrt(.5), 0, sqrt(.5)), not (.5,0,.5), by the way. The length of the rotated vector stays constant. To achieve a squared hypotenuse of 1, you add .5, 0, and .5, not .25, 0, and .25, which would shorten your vector.

Glad to hear it. Rotate those vectors like they were on the Witches' Wheel!

Thanks! Worked great.

One thing to note is that you cannot do:

```
vector = vector * Quaternion.AngleAxis(-45, Vector3.up);
```

and must do

```
vector = Quaternion.AngleAxis(-45, Vector3.up) * vector;
```

as there are some reasons internal to Unity.

**Answer** by elhispano
·
Feb 10, 2013 at 03:00 PM

That operation is dependent on the order.
rotatedVector = Quaternion * vector OK
rotatedVector = vector * Quaternion won´t works and will launch a compiler error

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