Singles, best of three games to 21. You are at the near end; the camera sits
behind your baseline.
Move arrow keys or W A S D, or drag on the court
Stroke 1 clear · 2 drop · 3 smash · 4 net shot (or Q E R F)
Aim your stroke goes where you are moving at the moment you hit it
Serve space · Pause P · New match N · Help H
The rules it plays by
Everything below is taken from BWF Statutes, Section 4.1: Laws of Badminton
(in force 23/05/2021, version 1.0). Clause numbers are quoted in the document's own style.
Law 1.1 the court is marked with lines 40 mm wide;
Law 1.3all the lines form part of the area which they define — so a shuttle
touching a line is IN.
Diagram A the court is 13.400 m long and
6.100 m wide for doubles,
5.180 m for singles; the short service line is
1.980 m from the net and the doubles long service line
0.720 m clear of the back boundary line.
The printed note gives the diagonal as 14.723 m, which is exactly
√(13.400² + 6.100²).
Law 1.10 the net top is 1.524 m at the centre
and 1.550 m over the side lines;
Law 1.7 the net is 760 mm deep.
Law 2 the shuttle has 16 feathers,
weighs 4.74–5.50 g,
and its feather tips lie on a circle of 58–68 mm.
Law 3 a shuttle of correct speed, hit with a full underhand stroke from over the back
boundary line, lands not less than 530 mm and not more
than 990 mm short of the other back boundary line.
The yellow marks near the far corners are Diagram B's optional testing marks.
Law 9.1.6 the whole shuttle must be below 1.150 m
when the server strikes it; this game serves from
0.950 m, so a legal serve is legal by construction.
Laws 10.1.1 / 10.1.2 you serve from the right service court when your own score
is nought or even, and from the left when it is odd — your score, not the total.
Laws 7.2 / 7.4 / 7.5 a game goes to 21; at 20-all the
first side two points clear wins; at 29-all the 30th point wins.
Law 7.6 the winner of a game serves first in the next.
Law 8.1 ends change after each game, and again in the third game when a side first
reaches 11.
Why the shuttle does not fly like a ball
A shuttlecock is a high-drag, self-orienting body, and this game models it as one:
position, velocity, body axis and angular velocity are integrated together, so the shuttle
really does flip and really does stall.
The racket meets the cork, so the shuttle leaves the strings skirt-first and flips
to fly cork-first. Measured here: 4.17 ms and
0.222 m on the Law 3 stroke — and the flip
distance stays constant from 10 to 120 m/s, because both the racket impulse and the
aerodynamic restoring torque scale with speed.
Drag then dominates. A clear travels 2.05 times
further before its apex than after it. Remove the drag and the identical launch is a
symmetric parabola, ratio 0.98.
Terminal velocity comes out at
6.71 m/s, so a smash that leaves the
racket at over 200 km/h arrives at walking pace.
The drag is derived, not chosen. Law 3 is one equation in two unknowns — it
fixes no launch speed, angle, contact height or air density. Closing it with a published
measurement of the shuttle's drag area solves the test stroke at
61.2 m/s
(220 km/h) at
23.8°. Inverting it, the
460 mm band pins the terminal velocity to 6.63–6.79 m/s — which contains the
measured 6.7 m/s. A non-flipping shuttle misses the band by
4.67 m.
Reconstructed, because the Laws do not fix them: air at ICAO standard sea level
(1.225 kg/m³), standard gravity, the shuttle's mass and skirt diameter taken as the
midpoints of the Law 2 ranges, the contact height and elevation of the Law 3 stroke, the
shape of the net between its two stated heights, the drag penalty while flying skirt-first,
and everything about the players — the Laws fix no racket mass, string tension or
player speed.
About
Badminton is a sport, not a product: nobody owns it, and this is not a reimplementation of
any particular video game. The rules are those of the Badminton World Federation
(BWF, founded 1934 as the International Badminton Federation), published as
BWF Statutes, Section 4.1: Laws of Badminton. The aerodynamic constants that the Laws
do not fix come from C. Cohen, B. Darbois Texier, D. Quéré and C. Clanet,
“The physics of badminton”, New Journal of Physics17 (2015)
063001. This game is an independent implementation, not affiliated with or endorsed by the
BWF. It differs from the sport in ways listed in CREDITS.txt: singles only, one shuttle
speed, no lets or service-judge calls, and simplified player movement.