#GLU_MAP1_VERTEX_4. To mark the end of the NURBS curve definition, call nurb:EndCurve().
GL evaluators are used to render the NURBS curve as a series of line segments. Evaluator state is preserved during rendering with
#GLU_EVAL_BIT) and gl.PopAttrib(). See gl.PushAttrib for details on exactly what state these calls preserve.
Please consult an OpenGL reference manual for more information.