Confused with matrices in GLSL shaders

I tried to read all of the https://urho3d.github.io/documentation/HEAD/pages.html but couldn’t quite understand well enough how do the transformation matrices work in Urho3D.

Specifically, when I set shader parameter like this:

SetShaderParameter("MyRot", node_->GetWorldRotation().RotationMatrix());

I can access that data in vertex shader by cMyRot.

But if I try to get the rotation already supplied shader variables, like this:

mat4 modelMatrix = iModelMatrix;
mat3 my_rot = mat3(modelMatrix);

I get totally different kind of data, expecting to just get the world transform matrix as in the previous code block.

I don’t know lot about glsl and Urho3D approach on it, so any pointers or ideas would be appreciated

Solution that worked for me:

mat3 get_rot_from_mat4 (mat4 m) {
    mat3 m3 = transpose(mat3(m));

    // extract the scaling factors
    float scaling_x = length(m3[0]);
    float scaling_y = length(m3[1]);
    float scaling_z = length(m3[2]);

    // and remove all scaling from the matrix
    m3[0] /= scaling_x;
    m3[1] /= scaling_y;
    m3[2] /= scaling_z;
    return m3;
}