1. A method, comprising: sending attitude reference data to a controller disposed with a drilling tool; converting the attitude reference data into a vector unit in vector space representing a drill attitude; instituting a control law to stabilize the drill attitude and to drive the drill attitude to a set point; performing a coordinate transformation for implementing a controller, comprising evaluating one of a gravity and a magnetic tool face that is equivalent to a zero relative tool face, wherein an angular direction of an arbitrary globally referenced vector is projected onto a plane at right angles to a tool face; implementing the controller; and controlling an instantaneous attitude of the drilling tool in response to implementing the controller.