Rotating along z axis

[jose]

Hi there, I am having a problem. This is the situation: I have a 2d rectangle and I need it to follow a spline (drawn over the edege of a curving, continous terrain). I use the SplineWalkerDistance script as a base, but I need the rectangle to rotate only around the z axis. So if for example the terrain curves up 40 degrees, the rectangle rotates around the z axis 40 degrees. I am trying to use this code (the rest of the script is the same as the original), but it is not working.

Code:

if (SetOrientation) {
 Quaternion tan = new Quaternion();
 tan = Spline.GetOrientationFast(tf);

 transform.rotation = Quaternion.Euler(0f,0f,tan.z);
 Dir = dir;
}

I'm probably not understanding how transform works in unity, or how GetOrientationFast works, but I've read the documentation and I just can't figure out how to do it.

Thank you
Ps: I have attached a screen capture to ilustrate the problem.