((function faceforward
   (signature float
     (parameters
       (declare (in) float N)
       (declare (in) float I)
       (declare (in) float Nref))
     ((if (expression bool < (expression float * (var_ref Nref) (var_ref I)) (constant float (0)))
          ((return (var_ref N)))
	  ((return (expression float neg (var_ref N)))))))

   (signature vec2
     (parameters
       (declare (in) vec2 N)
       (declare (in) vec2 I)
       (declare (in) vec2 Nref))
     ((if (expression bool < (expression float dot (var_ref Nref) (var_ref I)) (constant float (0)))
          ((return (var_ref N)))
	  ((return (expression vec2 neg (var_ref N)))))))

   (signature vec3
     (parameters
       (declare (in) vec3 N)
       (declare (in) vec3 I)
       (declare (in) vec3 Nref))
     ((if (expression bool < (expression float dot (var_ref Nref) (var_ref I)) (constant float (0)))
          ((return (var_ref N)))
	  ((return (expression vec3 neg (var_ref N)))))))

   (signature vec4
     (parameters
       (declare (in) vec4 N)
       (declare (in) vec4 I)
       (declare (in) vec4 Nref))
     ((if (expression bool < (expression float dot (var_ref Nref) (var_ref I)) (constant float (0)))
          ((return (var_ref N)))
	  ((return (expression vec4 neg (var_ref N)))))))
))
