The One-Armed MATLAB

Mike Croucher
/
The One-Armed MATLAB
on 10 Nov 2026
4
49
14
4
9935
game.m
function g = game()
% The One-Armed MATLAB, a fruit machine. You get 10 pulls; tap to pull
% the lever and bank what lands on the centre line. Now and then a losing spin awards NUDGES: a light
% cycles over the reels and COLLECT, and a tap nudges the lit reel down.
g.init = @init0;
g.update = @upd;
g.render = @rend;
end

function s = init0(ax)
bg = [.55 .04 .08];
ax.Color = bg; ax.SortMethod = 'childorder'; ax.XLim = [0 800]; ax.YLim = [0 600];
% reel strips: 1 cherry, 2 lemon, 3 plum, 4 Simulink block, 5 NED, 6 membrane
s.R = ['123142631254'; '214312213654'; '312416234152'] - '0';
s.X = [280 400 520];
for r = 1:3
    x = s.X(r) + [-55 55];
    rc(ax, x, [220 460], [1 .97 .88], 'none');
    h.st(r) = hgtransform(ax);
    for k = -1:14
        sym(h.st(r), s.R(r, mod(k, 12)+1), s.X(r), 340 + k*80, 1);
    end
    % NED letters are the only white lines on a strip
    h.ned{r} = findobj(h.st(r), 'Type', 'line', 'Color', [1 1 1]);
    for y = [220 400]
        set(rc(ax, x, y+[0 60], 'k', 'none'), 'FaceAlpha', .18);
    end
end
% cabinet face masks the reels above and below the windows
rc(ax, [0 800], [460 600], bg, 'none'); rc(ax, [0 800], [0 220], bg, 'none');
for x = s.X
    set(rc(ax, x+[-58 58], [217 463], 'none', [.85 .85 .9]), 'LineWidth', 4);
end
h.wl = line(ax, [212 588], [340 340], 'LineWidth', 2.5);
% marquee with chasing bulbs
G = [1 .85 .25];
set(rc(ax, [40 760], [495 585], [.2 0 .03], G), 'LineWidth', 3);
tx(ax, 400, 540, 'THE ONE-ARMED MATLAB', 28, G);
h.b = scatter(ax, [40:30:760 40:30:760], [585+0*(1:25) 495+0*(1:25)], 70, 'filled');
% pay table
set(rc(ax, [12 200], [222 462], [.2 0 .03], G), 'LineWidth', 2);
tx(ax, 106, 447, 'PAYS', 12, G);
P = '666555444333222111110100' - '0';
V = [100 50 30 15 10 10 3 1];
for i = 1:8
    y = 446 - 24*i;
    for j = find(P(3*i-2:3*i))
        sym(ax, P(3*i-3+j), 15 + 33*j, y, .36);
    end
    tx(ax, 172, y, string(V(i)), 12, 'w');
end
tx(ax, 81, 230, 'ANY PAIR', 11, 'w'); tx(ax, 172, 230, '2', 12, 'w');
% lever
h.arm = line(ax, [690 0], [320 0], 'Color', [.8 .8 .85], 'LineWidth', 9, 'Marker', 'o', 'MarkerIndices', 2, 'MarkerSize', 30, 'MarkerFaceColor', 'r');
el(ax, 690, 320, 24, 24, [.7 .7 .75]);
% displays, COLLECT button, coin shower, messages
for i = 1:3
    x = 260*i - 120;
    set(rc(ax, x+[-85 85], [110 150], 'k', [.85 .85 .9]), 'LineWidth', 2);
    h.d(i) = tx(ax, x, 130, '', 16, [1 .3 .1]);
end
h.col = rc(ax, [330 470], [30 75], 'k', [.85 .85 .9]);
tx(ax, 400, 52, 'COLLECT', 16, 'k');
h.cur = line(ax, nan, nan, 'Color', 'y', 'LineWidth', 5);
h.bot = tx(ax, 400, 185, '', 16, 'w');
z = nan(1, 40);
h.co = scatter(ax, z, z, 'MarkerFaceColor', [1 .8 .1], 'MarkerEdgeColor', [.6 .4 0]);
h.msg = tx(ax, 400, 330, '', 18, G);
set(h.msg, 'BackgroundColor', [.2 0 .03], 'EdgeColor', G, 'LineWidth', 3, 'Margin', 14);
set(findobj(ax.Children), 'HitTest', 'off', 'PickableParts', 'none');
s.h = h;
s.t = 0; s.best = 0;
s = reset0(s);
end

function h = rc(p, x, y, f, e)
h = patch(p, x([1 2 2 1]), y([1 1 2 2]), 'k', 'FaceColor', f, 'EdgeColor', e);
end

function h = tx(p, x, y, str, sz, c)
h = text(p, x, y, str, 'FontSize', sz, 'Color', c, 'FontWeight', 'bold', 'HorizontalAlignment', 'center');
end

function el(p, x, y, a, b, c)
t = linspace(0, 2*pi, 30);
patch(p, x + a*cos(t), y + b*sin(t), c, 'EdgeColor', c*.6);
end

function sym(p, id, x, y, k)
switch id
    case 1 % cherries
        line(p, x+k*[-11 3 12], y+k*[-2 27 -4], 'Color', [.2 .45 .1], 'LineWidth', 3*k);
        el(p, x+9*k, y+27*k, 9*k, 4*k, [.25 .65 .15]);
        for d = [-11 12]
            el(p, x+d*k, y-13*k, 13*k, 13*k, [.85 .05 .12]);
            el(p, x+(d-4)*k, y-8*k, 3*k, 3*k, [1 .75 .75]);
        end
    case 2 % lemon
        a = linspace(0, 2*pi, 40);
        patch(p, x+31*k*cos(a).*(1+.15*cos(a).^12), y+21*k*sin(a), [1 .88 .1], 'EdgeColor', [.75 .55 0], 'LineWidth', 1.5);
    case 3 % plum
        line(p, x+k*[0 4], y+k*[20 32], 'Color', [.35 .2 .05], 'LineWidth', 3*k);
        el(p, x, y-2*k, 25*k, 24*k, [.48 .12 .58]);
        el(p, x-11*k, y+6*k, 4*k, 7*k, [.8 .6 .85]);
    case 4 % Simulink Sine Wave block
        B = [0 .4 .75];
        a = -16:2:16;
        line(p, x+k*[24 34 NaN a], y+k*[0 0 NaN 9*sin(a/5)], 'Color', B, 'LineWidth', 2.5*k);
        patch(p, x+k*[34 42 34], y+k*[-6 0 6], B, 'EdgeColor', B);
        set(rc(p, x+k*[-22 22], y+k*[-18 18], 'none', B), 'LineWidth', 2.5*k);
    case 5 % NED bar, lettered with lines so the cabinet can mask it
        rc(p, x+k*[-37 37], y+k*[-19 19], 'k', [.6 .6 .6]);
        % letter strokes packed as characters (code - 70); '~' breaks a stroke
        q = ['++99~M??M~?J~SSZaaZS'; '<P<P~PP<<~FF~<PPJB<<'] - 70;
        q(q > 50) = NaN;
        line(p, x+k*q(1,:), y+k*q(2,:), 'Color', 'w', 'LineWidth', 3.5*k);
    case 6 % L-shaped membrane: the jackpot
        z = membrane(1, 6);
        z(~z) = NaN;
        [u, v] = meshgrid(linspace(1, -1, 13));
        q = (z - min(z(:)))/range(z(:));
        surface(p, x+k*(24*(u-v)+8), y+k*(9*(u+v) + 34*z - 12), 0*z, cat(3, .8+.2*q, .25+.65*q, .1*q), 'FaceColor', 'interp', 'EdgeColor', [.6 .2 0], 'LineWidth', .3);
end
end

function s = reset0(s)
[s.win, s.nud, s.cr, s.sp, s.curT, s.ann, s.fl] = deal(0);
s.pl = 10;
[s.mode, s.lp, s.cur] = deal(1);
s.o = randi(12, 1, 3) - 1; [s.tg, s.st, s.res] = deal(s.o); s.bt = s.o + 9;
s.c = nan(4, 40);
end

function s = upd(s, dt, pr)
s.t = s.t + dt;
s.ann = s.ann + dt;
s.fl = max(0, s.fl - dt);
s.lp = s.lp + dt;
s.bt = s.bt + dt;
% coins: x, y, vx, vy under gravity
s.c(1:2,:) = s.c(1:2,:) + s.c(3:4,:)*dt;
s.c(4,:) = s.c(4,:) - 900*dt;
if s.mode == 4
    if pr && s.ann > 1
        s = reset0(s);
    end
    return
end
% reels free-spin until given a stop target, then ease onto it and bounce
s.sp = s.sp + dt;
f = isinf(s.tg);
s.o(f) = mod(s.o(f), 12);
f = f & s.sp > s.st;
T = ceil(s.o) + 2;
s.tg(f) = T(f) + mod(s.res(f) - T(f), 12);
m = s.o < s.tg;
s.o = min(s.tg, s.o + min(18, 3 + 12*(s.tg - s.o))*dt);
s.bt(m & s.o == s.tg) = 0;
if any(s.o ~= s.tg)
    return
end
s.o = mod(s.o, 12);
s.tg = s.o;
w = pay(s);
if s.mode == 1
    if ~s.pl
        s.mode = 4;
        s.ann = 0;
    elseif pr
        % pull the lever: pure luck decides where each reel stops
        s.pl = s.pl - 1;
        [s.win, s.sp, s.lp] = deal(0);
        s.mode = 2;
        s.tg(:) = inf;
        s.res = randi(12, 1, 3) - 1;
        % weighted stops, like a real machine's virtual reel: each reel
        % lands on its NED 18% of the time, 10x the odds of NED NED NED
        s.res(rand(1, 3) < .105) = 10;
        s.st = 0.8 + 0.45*(0:2);
    end
elseif s.mode == 2
    if w || rand > 0.1
        s = fin(s, w);
    else
        [s.mode, s.nud, s.cur, s.curT] = deal(3, 1, 1, 0);
    end
else
    % nudging: the light dwells on each reel, then COLLECT
    s.curT = s.curT + dt;
    if s.curT >= 0.75
        s.curT = 0;
        s.cur = mod(s.cur, 4) + 1;
    end
    if w || ~s.nud || (pr && s.cur == 4)
        s = fin(s, w);
    elseif pr
        s.tg(s.cur) = s.tg(s.cur) + 1;
        s.nud = s.nud - 1;
        s.curT = 0;
    end
end
end

function [w, c] = pay(s)
c = s.R(sub2ind([3 12], 1:3, mod(round(s.o), 12) + 1));
P = [10 10 15 30 50 100];
w = 0;
if all(c == c(1))
    w = P(c(1));
elseif c(1) == 1
    w = 1 + 2*(c(2) == 1);
elseif c(1) == c(2)
    w = 2;
end
end

function s = fin(s, w)
s.cr = s.cr + w;
s.best = max(s.best, s.cr);
[s.win, s.fl, s.nud, s.mode] = deal(w, 2*(w > 0), 0, 1);
% a shower of coins from the payout tray, more for bigger wins
n = min(40, 3*w);
s.c(:, 1:n) = [400 + 30*randn(1, n); 75 + 0*(1:n); 160*randn(1, n); 350 + 300*rand(1, n)];
end

function rend(~, s)
h = s.h;
[~, c] = pay(s);
% damped bounce as a reel lands; NED flickers like neon on the line
o = s.o + .2*sin(17*s.bt).*exp(-6*s.bt);
for r = 1:3
    h.st(r).Matrix = makehgtform('translate', [0 -mod(o(r), 12)*80 0]);
    k = [1 1 1];
    if c(r) == 5 && s.mode ~= 2
        k = [1 .3 .85]*(.35 + .65*(sin(31*s.t)*sin(9*s.t) > -.5));
    end
    set(h.ned{r}, 'Color', k);
end
set(h.co, 'XData', s.c(1,:), 'YData', s.c(2,:), 'SizeData', 15 + 110*abs(cos(9*s.t + (1:40))));
% bulbs chase, faster on a win; the win line flashes
f = s.fl > 0;
p = mod(floor(s.t*(3 + 9*f)), 2);
Y = [1 .9 .4; .35 .15 0];
h.b.CData = Y(1 + mod((1:50) + p, 2), :);
k = [.9 0 0];
if f && mod(s.t, .25) < .12
    k = [1 .9 0];
end
h.wl.Color = k;
% lever swings down then back on a pull
b = 0.25 + 2.6*sin(pi*min(1, s.lp/0.5));
set(h.arm, 'XData', [690 690+150*sin(b)], 'YData', [320 320+150*cos(b)]);
set(h.d, {'String'}, cellstr(compose("%s %d", ["BANK"; "PULLS"; "WIN"], [s.cr; s.pl; s.win])));
% nudge light
n = s.mode == 3;
x = [nan nan]; y = x;
if n
    x = [323 477]; y = [23 82];
    if s.cur < 4
        x = s.X(s.cur) + [-63 63]; y = [212 468];
    end
end
set(h.cur, 'XData', x([1 2 2 1 1]), 'YData', y([1 1 2 2 1]), 'Visible', mod(s.t, .25) < .18);
h.col.FaceColor = [.3 .3 .3] + .7*[1 1 0]*n;
m = 'TAP TO PULL THE LEVER';
if n && s.cur == 4
    m = 'TAP TO COLLECT';
elseif n
    m = 'NUDGE! TAP TO DROP THE LIT REEL';
elseif s.win == 100
    m = 'JACKPOT!!  +100';
elseif s.win
    m = sprintf('WINNER!  +%d', s.win);
end
set(h.bot, 'String', m, 'Visible', s.mode < 4);
m = '';
if s.mode == 4
    m = sprintf('GAME OVER\n\nYou banked %d\nBest %d', s.cr, s.best);
    if s.ann > 1
        m = [m newline newline 'TAP TO PLAY AGAIN'];
    end
end
set(h.msg, 'String', m, 'Visible', ~isempty(m));
end
Play Game
Preview

Play Game opens this in MATLAB Drive. Click Run this app there to play.