GOING UP: you are the lift attendant, and it only stops when you tap

Praneel
/
GOING UP: you are the lift attendant, and it only stops when you tap
on 6 Nov 2026
2
8
5
1
9444
game.m
function g = game()
% GOING UP: you are the lift attendant, and the lift never stops on its
% own. Tap to stop level with a floor, tap again to go. People wear
% their floor's colour.
g.init = @initState;
g.update = @updateState;
g.render = @renderFrame;
end

function s = initState(ax)
C = struct('wall',[.12 .11 .16], 'car',[.86 .74 .5], 'red',[.93 .3 .27], ...
    'gold',[1 .84 .4], 'dim',[.55 .56 .66]);
F = [.96 .46 .42; .98 .7 .32; .64 .83 .4; .32 .78 .7; .4 .62 .96; .74 .52 .93];
set(ax, 'XLim',[0 800], 'YLim',[0 600], 'Color',C.wall);
s = struct('C',C, 'F',F, 'M',20, 'P',60, 'fy',40 + 84*(0:5)', 'cap',4, 'tol',12);

% Static building: a tinted band per floor, slabs either side of the shaft.
y = s.fy';
boxes(ax, 90, 710, y, y + 84, C.wall + 0.2*(F - C.wall));
boxes(ax, repmat([90 440], 1, 6), repmat([360 710], 1, 6), repelem(y, 2) - 6, ...
    repelem(y, 2), repelem(0.75*F, 2, 1));
boxes(ax, 360, 440, 34, 544, [.06 .06 .09]);
set(text(ax, 60 + 0*y, y + 42, num2cell('G12345'), 'FontSize',20, 'FontWeight','bold', ...
    'HorizontalAlignment','center'), {'Color'}, num2cell(F, 2));

s.h.cable = line(ax, [400 400], [0 544], 'Color',C.dim, 'LineWidth',1.5);
s.h.car = patch(ax, 'Vertices',boxV(367, 433, 0, 76), 'Faces',1:4, ...
    'FaceColor',[.2 .17 .2], 'EdgeColor',C.car, 'LineWidth',3);
% Passengers: one patch of 6-vertex bodies, one scatter of heads, one
% patch of patience bars. Unused slots sit at NaN and are not drawn.
M = s.M;
pool = @(k) patch(ax, 'Faces',reshape(1:k*M,k,M)', 'Vertices',nan(k*M,2), ...
    'FaceVertexCData',zeros(M,3), 'FaceColor','flat', 'EdgeColor','none');
s.h.body = pool(6);
s.h.head = scatter(ax, nan(M,1), nan(M,1), 75, [.96 .84 .7], 'filled');
s.h.bar = pool(4);
s.h.gate = line(ax, nan, nan, 'Color',C.car, 'LineWidth',2);
s.h.fx = scatter(ax, nan(s.P,1), nan(s.P,1), 10, ones(s.P,3), 'filled');
s.h.panel = boxes(ax, 120, 680, 345, 530, [.05 .05 .08]);
s.h.panel.FaceAlpha = 0.8;
s.h.lives = scatter(ax, [380 400 420], [578 578 578], 70, C.gold, 'filled');
label = @(x, y, sz, al) text(ax, x, y, '', 'FontSize',sz, 'FontWeight','bold', ...
    'Color',[.95 .92 .86], 'HorizontalAlignment',al);
s.h.score = label(20, 578, 18, 'left');
s.h.best = label(780, 578, 14, 'right');
s.h.title = label(400, 478, 48, 'center');
s.h.sub = label(400, 428, 13, 'center');
s.h.cue = label(400, 380, 16, 'center');
s.h.hint = label(400, 16, 12, 'center');
s.h.pop = label(0, 0, 15, 'left');
% Nothing drawn may swallow a click meant for the button.
set(findobj(ax.Children), 'HitTest','off', 'PickableParts','none');
s.h.ax = ax;

[s.t, s.best, s.overAt] = deal(0);
s = newRound(s);
s.mode = 0;
end

function s = newRound(s)
z = zeros(s.M,1);
[s.ps, s.pf, s.pd, s.side, s.pp, s.pmax, s.pt, s.posX, s.posY] = deal(z);
[s.fz, s.fv, s.fl] = deal(nan(s.P,1), zeros(s.P,1), zeros(s.P,1));
s.fc = ones(s.P,3);
[s.fk, s.score, s.played, s.jolt, s.ride, s.door, s.open] = deal(0);
[s.msgAt, s.stopAt] = deal(-inf);
s.msg = '';
s.cy = s.fy(1);
s.go = true;
s.lives = 3;
s.spawnT = 0.5;
s.mode = 1;
end

function s = updateState(s, dt, pressed)
s.t = s.t + dt;
s.v = 190 - 80*exp(-s.played/70);
if s.mode ~= 1
    if pressed && (s.mode == 0 || s.t - s.overAt > 0.9)
        s = newRound(s);
    end
    pressed = s.mode ~= 1 && autopilot(s);
end
if pressed
    s = toggleLift(s);
end

L = s.played;
s.played = s.played + dt*(s.mode == 1);
% Height is a triangle wave of the distance travelled: the lift bounces
% between ground (40) and the top floor (460) with no direction flag.
s.ride = s.ride + s.go*s.v*dt;
s.cy = 460 - abs(mod(s.ride, 840) - 420);
s.door = min(1, max(0, s.door + dt*(12*(~s.go && s.open) - 6)));
s = spawnPassenger(s, dt, L);

% Waiting passengers lose patience; at zero they storm off and cost a life.
w = s.ps == 1;
s.pp(w) = s.pp(w) - dt;
gaveUp = w & s.pp <= 0;
s.ps(gaveUp) = 4;
if s.mode == 1 && any(gaveUp)
    s.lives = s.lives - nnz(gaveUp);
    s.jolt = 1;
    if s.lives <= 0
        s.mode = 2;
        s.overAt = s.t;
        s.best = max(s.best, s.score);
    end
end

% Leavers walk off along their floor; everyone else is placed by rank.
lv = s.ps >= 3;
s.posX(lv) = s.posX(lv) + s.side(lv)*150*dt;
s.ps(lv & abs(s.posX - 400) > 450) = 0;
w = s.ps == 1;
r = s.ps == 2;
ahead = sum(w' & s.pf' == s.pf & s.side' == s.side & s.pt' < s.pt, 2);
s.posX(w) = 400 + s.side(w).*(64 + 26*ahead(w));
s.posY(w | lv) = s.fy(max(s.pf(w | lv), 1));
seat = sum(r' & s.pt' < s.pt, 2);
s.posX(r) = 377 + 15*seat(r);
s.posY(r) = s.cy;

s.fl = s.fl - dt;
s.fv = s.fv*(1 - 3*dt);
s.fz = s.fz + s.fv*dt;
s.fz(s.fl <= 0) = nan;
s.jolt = max(0, s.jolt - 2.5*dt);
end

function s = toggleLift(s)
s.stopAt = s.t;
if ~s.go
    s.go = true;
    s.open = false;
    return
end
s.go = false;
s.msgAt = s.t;
[e, f] = min(abs(s.cy - s.fy));
s.open = e <= s.tol;
if ~s.open
    % Stuck between floors: everyone waiting groans and loses patience.
    s.msg = 'CLUNK';
    s.jolt = max(s.jolt, 0.6);
    s.pp(s.ps == 1) = s.pp(s.ps == 1) - 1.5;
    return
end
s.ride = s.ride + (s.fy(f) - s.cy)*sign(420 - mod(s.ride, 840));
s.cy = s.fy(f);
off = find(s.ps == 2 & s.pd == f);
board = find(s.ps == 1 & s.pf == f);
[~, o] = sort(s.pt(board));
board = board(o(1:min(end, s.cap - nnz(s.ps == 2) + numel(off))));
s.ps(off) = 3;
s.pf(off) = f;
s.ps(board) = 2;
perfect = e < 4 && numel([off; board]) > 0;
s.msg = repmat('PERFECT', 1, perfect);
if numel(off) > 0
    s = burst(s, complex(400, s.cy + 40), 8*numel(off), s.F(f,:));
end
if perfect
    s = burst(s, complex(400, s.cy + 40), 16, s.C.gold);
end
if s.mode == 1
    s.score = s.score + numel(off) + perfect;
end
end

function s = spawnPassenger(s, dt, L)
s.spawnT = s.spawnT - dt;
j = find(s.ps == 0, 1);
if s.spawnT > 0 || isempty(j)
    return
end
s.spawnT = (0.9 + 2.1*exp(-L/50))*(0.7 + 0.6*rand);
f = randi(6);
side = 2*(rand < 0.5) - 1;
if nnz(s.ps == 1 & s.pf == f & s.side == side) > 3
    return
end
s.ps(j) = 1;
s.pf(j) = f;
s.pd(j) = mod(f + randi(5) - 1, 6) + 1;
s.side(j) = side;
s.pmax(j) = 12 + 12*exp(-L/60);
s.pp(j) = s.pmax(j);
s.pt(j) = s.t;
end

function tap = autopilot(s)
% Attract mode: stop dead level with any floor that has business, wait a
% moment, then go. The window is wide enough that no frame skips it.
[e, f] = min(abs(s.cy - s.fy));
busy = any(s.ps == 2 & s.pd == f) || (any(s.ps == 1 & s.pf == f) && nnz(s.ps == 2) < s.cap);
tap = (s.go && busy && e < s.v/55) || (~s.go && s.t - s.stopAt > 0.7);
end

function s = burst(s, z, n, col)
% Particles live in a ring buffer; new bursts overwrite the oldest.
k = mod(s.fk + (0:n-1)', s.P) + 1;
s.fk = k(end);
s.fz(k) = z;
s.fv(k) = (40 + 140*rand(n,1)).*exp(2i*pi*rand(n,1));
s.fl(k) = 0.4 + 0.5*rand(n,1);
s.fc(k,:) = repmat(col, n, 1);
end

function renderFrame(~, s)
h = s.h; C = s.C; t = s.t; cy = s.cy;

% Touching axes limits forces a full relayout, so shake only while jolted.
if s.jolt > 0 || ~isequal(h.ax.XLim, [0 800])
    q = 7*s.jolt^2;
    set(h.ax, 'XLim',[0 800] + q*sin(71*t), 'YLim',[0 600] + q*cos(53*t));
end
h.car.Vertices = boxV(367, 433, cy, cy + 76);
h.cable.YData = [cy + 76 544];
gx = 368 + linspace(0, 64*(1 - s.door) + 3*s.door, 7);   % the gate folds to the left
set(h.gate, 'XData',reshape([gx; gx; nan(1,7)], 1, []), ...
    'YData',repmat([cy + 2; cy + 74; nan], 7, 1)');

x = s.posX;
x(s.ps == 0) = nan;
y = s.posY + 6*(s.ps == 4).*abs(sin(14*t));
X = x' + [-8; 8; 9; 5; -5; -9];
Y = y' + [0; 0; 18; 23; 23; 18];
col = s.F(max(s.pd, 1),:);
set(h.body, 'Vertices',[X(:) Y(:)], 'FaceVertexCData',col + (s.ps == 4).*(C.red - col));
set(h.head, 'XData',x, 'YData',y + 31);
w = s.ps == 1;
frac = max(0, s.pp./max(s.pmax, 1));
x0 = x - 11;
x0(~w) = nan;
set(h.bar, 'Vertices',boxV(x0', x0' + 22*frac', y' + 41, y' + 45), ...
    'FaceVertexCData',C.red + frac.*([.5 .9 .45] - C.red));
life = max(s.fl, 0);
set(h.fx, 'XData',real(s.fz), 'YData',imag(s.fz), 'SizeData',3 + 40*life, ...
    'CData',C.wall + min(1, 2*life).*(s.fc - C.wall));

m = s.mode + 1;
a = min(1, (t - s.msgAt)/0.9);
tone = C.gold + strcmp(s.msg, 'CLUNK')*(C.red - C.gold);
set(h.pop, 'String',s.msg, 'Position',[445, cy + 50 + 30*a, 0], ...
    'Color',tone + a*(C.wall - tone), 'Visible',a < 1 && m == 2);
h.score.String = sprintf('DELIVERED  %d', s.score);
h.best.String = sprintf('BEST  %d', max(s.best, s.score));
h.lives.CData = C.gold + ((1:3)' > s.lives).*(C.dim*0.5 - C.gold);
% Rows are title, subtitle and cue; columns are the three modes.
msg = {'GOING UP', '', 'SHIFT OVER'
    'You are the lift attendant. The lift never stops unless you tap.', '', ...
    sprintf('Three passengers gave up.   Delivered %d   Best %d', s.score, s.best)
    'TAP TO START YOUR SHIFT', '', 'TAP FOR ANOTHER SHIFT'};
set(h.title, 'String',msg{1,m}, 'Color',C.gold + (m == 3)*(C.red - C.gold));
h.sub.String = msg{2,m};
set(h.cue, 'String',msg{3,m}, 'Visible',mod(t, 1) < 0.65 && (m == 1 || t - s.overAt > 0.9));
h.panel.Visible = m ~= 2;
h.hint.String = 'TAP to stop level with a floor, TAP again to go. Everyone wears the colour of their floor.';
end

function h = boxes(ax, x0, x1, y0, y1, col)
% Rectangles as one patch, one 4-vertex face each.
n = size(col, 1);
h = patch(ax, 'Faces',reshape(1:4*n,4,n)', 'Vertices',boxV(x0, x1, y0, y1), ...
    'FaceVertexCData',col, 'FaceColor','flat', 'EdgeColor','none');
end

function V = boxV(x0, x1, y0, y1)
X = [x0; x1; x1; x0] + 0*y0;
Y = [y0; y0; y1; y1] + 0*x0;
V = [X(:) Y(:)];
end
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