Certain aspects of GL behavior, when there is room for variation, may be controlled with hints. A hint is specified using
void Hint ( enum target, enum hint ) ;
target is a symbolic constant indicating the behavior to be controlled, and hint is a symbolic constant indicating what type of behavior is desired. target may be one of PERSPECTIVE_CORRECTION_HINT, indicating the desired quality of parameter interpolation; POINT_SMOOTH_HINT, indicating the desired sampling quality of points; LINE_SMOOTH_HINT, indicating the desired sampling quality of lines; POLYGON_SMOOTH_HINT, indicating the desired sampling quality of polygons; and FOG_HINT, indicating whether fog calculations are done per pixel or per vertex. hint must be one of FASTEST, indicating that the most efficient option should be chosen; NICEST, indicating that the highest quality option should be chosen; and DONT_CARE, indicating no preference in the matter.
The interpretation of hints is implementation dependent. An implementation may ignore them entirely.