Help with vector math and angles

Unity Engine
1

For reasons unknown, I need to find the signed angle between two vectors which are on the same plane. This is proving difficult for me.

Here’s images to explain:

Now, how do I get the signed angle from the red arrow to the green one?

The plane is imaginary and the vectors are in world space.

2

Try this method

public static float AngleSigned(Vector3 v1, Vector3 v2, Vector3 normal)
{
    return Mathf.Atan2(Vector3.Dot(normal, Vector3.Cross(v1, v2)), Vector3.Dot(v1, v2)) * Mathf.Rad2Deg;
}

“Vector3 normal” is a plane normal

1 Like
3

Seems to work great, thanks a lot for the help! :slight_smile:

4

Hello, I’m using this formula and it works for me too, but I need to understand why it works! Can someone explain it to me?