ALLEGRO_PRIM_QUALITY - Allegro 5 API

       Controls  the  quality  of  the approximation of curved primitives (e.g. circles).  Curved primitives are
       drawn by approximating them with a sequence of line segments.  By default, this  roughly  corresponds  to
       error of less than half of a pixel.

Allegro reference manual                                                           ALLEGRO_PRIM_QUALITY(3alleg5)

       ALLEGRO_PRIM_QUALITY - Allegro 5 API

              #include <allegro5/allegro_primitives.h>

              #define ALLEGRO_PRIM_QUALITY 10