3rd person character controller on a planet

So I am trying to create a 3rd person character controller that works on a planet, currently I have the player standing correctly where ever they go by setting the player's transform.up to it their position, but that causes a problem, when you set the transform.up the Y rotation of the player also gets reset, so to fix that I saved the player's y rotation before setting their transform.up than after setting it I added the y value back, but now I need to have the player rotate in the direction the camera is facing so I need help with doing that.

 

Avoid using Euler angles. It's best to use linear algebra. One possible way to add your yaw is to something like

transform.rotation *= Quaternion.AngleAxis(angle, transform.up);

. You'll probably want to get your yaw through a different method though. However, compositing quaternions can be quite powerful.

 

Where can I learn to use unity quaternions and learn general lenierar algebra?