anchor.diff:  %FIXME: This should be a callback so the behavior can do stuff like target-velocity calculations.
   forces(_TimeDelta, State) ->
   	#physical{
  -		force_abs = ForceAbs,
  -		force_rel = ForceRel,
  +		force_absolute = ForceAbs,
  +		force_relative = ForceRel,
   		orientation = Orientation,
   		torque_absolute = TorqueAbs,
   		torque_relative = TorqueRel
  
positive.code: 			Orientation
  		)
  	),
  	State#physical{
  		linear_velocity = LinearVelocity,
  		angular_velocity = AngularVelocity,
  		spin = Spin
  	}.
  
  %% ------------------------------------------------------------------------
  
  
negative.code: 		inverse_inertia_tensor = InverseInertia
  	} = State,
  
  	LinearVelocity = vector:multiply(InverseMass, LinearMomentum),
  
  	AngularVelocity = vector:multiply(InverseInertia, AngularMomentum),
  	{AngularVelocityX, AngularVelocityY, AngularVelocityZ} = AngularVelocity,
  