Rotating Vector3, linecast

Question

Hello, I am am creating a Physics2d.LineCast that starts in middle of the objects, and ends in same vector with x bigger by 1 unit. It looks like that:

alt text

I am trying to make this linecast follow transforms rotation, so for example, if I would rotate my transform by 90 degrees on Z axis, that would be my expectation (left) but instead I get linecast with weird rotation plus linecast is much longer (depends on transforms rotation)

alt text

I am drawing linecast and rotating it this way:

 void FixedUpdate ()
 {
         Vector3 myVector = transform.position + new Vector3(1, 0, 0);
         Vector3 rotatedVector = transform.rotation * myVector;
         Debug.DrawLine(transform.position, rotatedVector);
 }

But as you can see it does not work as intended, I would appreciate help how to rotate Vector3 properly, so it follows transforms rotation. Thank you.

Answer 1

Best Answer

Answer by Hellium · Jan 31, 2017 at 02:35 PM

In Vector Arithmetic, a sum of two vectors results in a point, not a vector while the difference between two points results in a vector. Here, you need to rotate a directional vector, thus, simply do the following :

     void FixedUpdate()
     {
         Vector3 rotatedVector = transform.rotation * new Vector3(1, 0, 0);
         Debug.DrawLine( transform.position, transform.position + rotatedVector );
     }

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Matthewek · Jan 31, 2017 at 02:38 PM 0

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Thank you very much, indeed I did not think about it this way, once again thanks.

Rotating Vector3, linecast

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