ref: 9090c1e8d2c462e217ab723c684f5a151295a0f6
dir: /dat.h/
#define Eg 9.81 /* earth's gravity (m·s⁻²) */
#define Cd 0.45 /* drag coefficient for a sphere */
#define ρ 1.293 /* air density (kg·m⁻³) */
#define M2PIX (1.0/PIX2M)
enum {
Stheta = 0,
Spos,
Svel,
Sdrag,
Sdeltax,
Seta,
Sscale,
SLEN,
};
typedef struct Projectile Projectile;
struct Projectile
{
Point2 p, v;
double mass;
double r;
};