Calculate Rotation based on mesh normals

Questions & Answers
1

i have a plane that i want to rotate to face a certain direction, but not using transform.rotation but by rotating the vertices. i already have the code for rotating mesh vertices arround a center :

        var path = GetPath();
        var angle = Quaternion.FromToRotation(mf.mesh.normals[0], path[0].rotation.eulerAngles);
        var center = mf.mesh.bounds.center;

        for (int i = 0; i < mf.mesh.vertices.Length; i++)
        {
            mf.mesh.vertices _= RotateVertex(center, mf.mesh.vertices*, angle);*_

}
public Vector3 RotateVertex(Vector3 center, Vector3 vert, Quaternion angle)
{
// rotates the vertex
vert = angle * (vert - center) + center;
return vert;
}
i only need to find a way to calculate the rotation of the mesh based on the direction and the mesh normals like this :
[186883-screenshot-2021-09-29-221051.png|186883]_
_

2

Given only mesh normals you cannot calculate the rotation of the mesh fully, because you can always rotate the mesh about the normal and have a new mesh rotation but the same normal. You can calculate a mesh rotation by using Quaternion.LookRotation and feed in the normal. You will also have to feed in another vector, but you could feed in any vector that is orthogonal to the normal vector, because as I mentioned before there are really infinite rotations given a normal vector.
**
Also the order that you feed the vectors in depends on how your plane set up relative to the x/y/z axis. If “up” for the plane is in the same direction as the normals, then feed in the normal vector as up and the orthogonal vector as forward.
**
If you really want to get the ACTUAL EXACT rotation for the plane, you will need more information.