| ALLEGRO_PI(3alleg5) | ALLEGRO_PI(3alleg5) |
ALLEGRO_PI - Allegro 5 API
#include <allegro5/allegro.h>
#define ALLEGRO_PI 3.14159265358979323846
C99 compilers have no predefined value like M_PI for the constant π, but you can use this one instead.
| Allegro reference manual |