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