Neon Grid Defense: One-Button Towers

Mike Croucher
/
Neon Grid Defense: One-Button Towers
on 8 Nov 2026
2
13
4
0
9509
game.m
function g = game()
% Neon Grid Defense: one-button tower defense. A ring cycles round the
% build spots; tap to build a tower on an empty spot or upgrade the tower
% that is there.
g.init = @init0;
g.update = @upd;
g.render = @rend;
end

function s = init0(ax)
ax.YDir = 'reverse';
ax.XLim = [0 800];
ax.YLim = [0 600];
ax.Color = [0.02 0.02 0.07];
P = [-30 130;250 130;250 330;110 330;110 490;450 490;450 230;650 230;650 450;830 450];
s.P = P;
s.S = [170 220;330 200;550 130;540 320;750 330;740 540;350 400;300 555;180 420;40 410];
s.cl = [0; cumsum(hypot(diff(P(:,1)), diff(P(:,2))))];
s.nS = 10;
s.nE = 32;
a = linspace(0, 2*pi, 25);
s.C = [cos(a); sin(a)];
% tower shapes per level, enemy shapes per type
s.T = {ng(3, 15, -pi/2), ng(4, 16, 0), st(5, 21, 9)};
s.E = {ng(4, 1, 0), ng(3, 1.1, 0), ng(6, 1, 0), st(6, 1, 0.5)};
% background grid
g = 0:40:800;
line(ax, reshape([g; g; nan*g], 1, []), reshape([0*g; 600+0*g; nan*g], 1, []), 'Color', [0.07 0.07 0.2]);
g = 0:40:600;
line(ax, reshape([0*g; 800+0*g; nan*g], 1, []), reshape([g; g; nan*g], 1, []), 'Color', [0.07 0.07 0.2]);
% path with glowing edges offset either side (right-angle corners)
line(ax, P(:,1), P(:,2), 'Color', [0 0.1 0.15], 'LineWidth', 36);
U = diff(P);
N = [-U(:,2) U(:,1)]./hypot(U(:,1), U(:,2));
N = [N(1,:); N(1:end-1,:)+N(2:end,:); N(end,:)];
for o = [-18 18]
    D = P + o*N;
    line(ax, D(:,1), D(:,2), 'Color', [0 0.35 0.45], 'LineWidth', 7);
    line(ax, D(:,1), D(:,2), 'Color', [0.4 1 1], 'LineWidth', 1.5);
end
patch(ax, [765 800 800 765], [425 425 475 475], [0.3 0 0.25], 'EdgeColor', [1 0.3 1], 'LineWidth', 3);
tx(ax, [783 405], 10, [1 0.3 1], 'CORE');
tx(ax, [30 100], 10, [0.4 1 1], '>> IN');
line(ax, s.S(:,1), s.S(:,2), 'LineStyle', 'none', 'Marker', 'o', 'MarkerSize', 26, 'MarkerFaceColor', [0.02 0.08 0.12], 'MarkerEdgeColor', [0 0.45 0.55], 'LineWidth', 2);
s.h.rng = line(ax, nan, nan, 'Color', 'y', 'LineStyle', ':', 'LineWidth', 1.5);
for i = 1:s.nS
    s.h.tw(i) = patch(ax, 0, 0, 'w', 'LineWidth', 2.5, 'FaceAlpha', 0.3);
    s.h.gl(i) = line(ax, nan, nan);
    s.h.sh(i) = line(ax, nan, nan, 'Color', [1 0.92 1]);
end
for k = 1:s.nE
    s.h.e(k) = patch(ax, 0, 0, 'w', 'LineWidth', 1.5, 'FaceAlpha', 0.3);
    s.h.hp(k) = line(ax, nan, nan, 'Color', [1 0.3 0.3], 'LineWidth', 3);
end
s.h.cur = line(ax, nan, nan, 'Color', 'y', 'LineWidth', 3);
s.h.cost = tx(ax, [0 0], 11, 'w', '');
s.h.hud = tx(ax, [180 24], 16, 'w', '');
s.h.msg = tx(ax, [400 300], 22, [0.3 1 1], '');
set(s.h.msg, 'BackgroundColor', 'k', 'EdgeColor', [0.3 1 1], 'LineWidth', 2, 'Margin', 14);
set(ax.Children, 'HitTest', 'off', 'PickableParts', 'none');
s = reset0(s);
s.mode = 0;
end

function h = tx(ax, p, sz, c, str)
h = text(ax, p(1), p(2), str, 'Color', c, 'FontName', 'Consolas', 'FontSize', sz, 'FontWeight', 'bold', 'HorizontalAlignment', 'center', 'Interpreter', 'none');
end

function s = reset0(s)
s.mode = 1;
[s.t, s.wave, s.left, s.spT, s.ann, s.flash, s.curT, s.int] = deal(0);
s.gold = 50;
s.lives = 5;
s.pause = 3;
s.cur = 1;
z = zeros(1, s.nS);
s.lv = z;
s.cd = z;
s.shT = z;
s.pop = z;
s.shX = zeros(s.nS, 2);
z = zeros(1, s.nE);
s.on = z > 0;
s.d = z;
s.hp = z;
s.mx = z + 1;
s.sp = z;
s.ty = z + 1;
end

function s = upd(s, dt, pr)
s.t = s.t + dt;
if s.mode ~= 1
    s.ann = s.ann + dt;
    if pr && (s.mode == 0 || s.ann > 1)
        s = reset0(s);
    end
    return
end
s.flash = max(0, s.flash - dt);
s.ann = max(0, s.ann - dt);
s.pop = max(0, s.pop - dt);
% build cursor: tap builds on an empty spot or upgrades a tower
s.curT = s.curT + dt;
if s.curT >= 0.65
    s.curT = 0;
    s.cur = mod(s.cur, s.nS) + 1;
end
c = cost(s, s.lv(s.cur));
if pr && c && s.gold >= c
    s.gold = s.gold - c;
    s.lv(s.cur) = s.lv(s.cur) + 1;
    s.curT = 0;
    s.pop(s.cur) = 0.3;
end
% endless waves, every 5th ends with a boss
if s.left == 0 && ~any(s.on)
    s.pause = s.pause - dt;
    if s.pause <= 0
        % interest on banked gold rewards saving for the right spot
        s.int = min(25, floor(s.gold/10));
        s.gold = s.gold + s.int;
        s.wave = s.wave + 1;
        s.left = min(3 + 2*s.wave, 30);
        s.spT = 0;
        s.pause = 3;
        s.ann = 2;
    end
end
w = s.wave;
s.spT = s.spT - dt;
k = find(~s.on, 1);
if s.left && s.spT <= 0
    r = rand;
    t = 1 + (w > 1 && r < min(0.4, 0.08*w)) + 2*(w > 2 && r > 1 - min(0.3, 0.05*w));
    if mod(w, 5) == 0 && s.left == 1
        t = 4;
    end
    HP = [3 2 9 45];
    SP = [63 120 41 32];
    s.on(k) = true;
    s.d(k) = 0;
    s.ty(k) = t;
    s.mx(k) = HP(t)*1.32^(w-1);
    s.hp(k) = s.mx(k);
    s.sp(k) = SP(t)*(1 + 0.015*w);
    s.left = s.left - 1;
    s.spT = max(0.35, 2.2 - 0.2*w);
end
% move; each leak costs a life (a boss costs 3)
s.d(s.on) = s.d(s.on) + s.sp(s.on)*dt;
lk = s.on & s.d >= s.cl(end);
if any(lk)
    s.lives = max(0, s.lives - sum(lk) - 2*sum(lk & s.ty == 4));
    s.on(lk) = false;
    s.flash = 0.6;
    if s.lives == 0
        s.mode = 2;
        s.ann = 0;
        return
    end
end
% towers shoot the enemy furthest along the path within range
s.cd = max(0, s.cd - dt);
s.shT = max(0, s.shT - dt);
[ex, ey] = pos(s, s.d);
DM = [1 2.2 4];
CD = [0.7 0.55 0.4];
GD = [7 6 14 50];
for i = find(s.lv > 0 & s.cd <= 0)
    v = s.lv(i);
    in = s.on & hypot(ex - s.S(i,1), ey - s.S(i,2)) < rr(v);
    if any(in)
        dd = s.d;
        dd(~in) = -1;
        [~, k] = max(dd);
        s.hp(k) = s.hp(k) - DM(v);
        s.cd(i) = CD(v);
        s.shT(i) = 0.12;
        s.shX(i,:) = [ex(k) ey(k)];
        if s.hp(k) <= 0
            s.on(k) = false;
            s.gold = s.gold + round(GD(s.ty(k))*(1 + 0.05*(w-1)));
        end
    end
end
end

function [x, y] = pos(s, d)
d = min(d, s.cl(end));
x = interp1(s.cl, s.P(:,1), d);
y = interp1(s.cl, s.P(:,2), d);
end

function c = cost(s, v)
% first two towers $50, then each new one costs $25 more; upgrades fixed
C = [25*max(2, 1+sum(s.lv > 0)) 70 110 0];
c = C(v+1);
end

function r = rr(v)
r = 85 + 25*v;
end

function rend(~, s)
h = s.h;
V = {'off', 'on'};
TC = [1 0.2 0.9; 0.3 0.6 1; 1 0.95 0.2];
for i = 1:s.nS
    v = s.lv(i);
    if v
        u = s.T{v}*(1 + s.pop(i));   % pop bigger on build/upgrade, then settle
        set(h.tw(i), 'XData', s.S(i,1)+u(1,:), 'YData', s.S(i,2)+u(2,:), 'FaceColor', TC(v,:), 'EdgeColor', TC(v,:));
    end
    h.tw(i).Visible = V{1 + (v > 0)};
    % laser: glow in the tower's colour plus a white core, both thinning as it fades
    q = s.shT(i);
    set([h.gl(i) h.sh(i)], 'XData', [s.S(i,1) s.shX(i,1)], 'YData', [s.S(i,2) s.shX(i,2)], 'Visible', V{1 + (q > 0)});
    set(h.gl(i), 'Color', TC(max(v, 1),:), 'LineWidth', 1 + 70*q);
    h.sh(i).LineWidth = 0.5 + 25*q;
end
% cursor ring, range preview and price
c = s.S(s.cur,:);
v = s.lv(s.cur);
r = 28 + 2*sin(9*s.t);
set(h.cur, 'XData', c(1)+r*s.C(1,:), 'YData', c(2)+r*s.C(2,:));
r = rr(min(v+1, 3));
set(h.rng, 'XData', c(1)+r*s.C(1,:), 'YData', c(2)+r*s.C(2,:));
k = cost(s, v);
W = {'BUILD', 'UP'};
t = 'MAX';
if k
    t = sprintf('%s $%d', W{1 + (v > 0)}, k);
end
col = [1 0.3 0.3];
if k && s.gold >= k
    col = [0.3 1 0.4];
end
set(h.cost, 'Position', [c(1) c(2)-40 0], 'String', t, 'Color', col);
% enemies spin as they travel
[ex, ey] = pos(s, s.d);
R = [11 9 14 22];
EC = [0.2 1 0.3; 1 1 0.2; 1 0.45 0.1; 1 0.2 0.6];
set([h.e(~s.on) h.hp(~s.on)], 'Visible', 'off');
for k = find(s.on)
    t = s.ty(k);
    a = 3*s.t + k;
    u = [cos(a) -sin(a); sin(a) cos(a)]*s.E{t}*R(t);
    set(h.e(k), 'XData', ex(k)+u(1,:), 'YData', ey(k)+u(2,:), 'FaceColor', EC(t,:), 'EdgeColor', EC(t,:), 'Visible', 'on');
    f = max(0, s.hp(k)/s.mx(k));
    set(h.hp(k), 'XData', ex(k) + R(t)*[-1, 2*f-1], 'YData', ey(k) - R(t) - 7 + [0 0], 'Visible', V{1 + (f < 1)});
end
% HUD and messages
col = [0.3 1 1];
if s.flash > 0 && mod(s.t, 0.2) < 0.1
    col = [1 0.15 0.15];
end
set(h.hud, 'String', sprintf('GOLD %d   LIVES %d   WAVE %d', s.gold, s.lives, s.wave), 'Color', col);
m = '';
if s.mode == 0
    m = sprintf('NEON GRID DEFENSE\n\nTap when the ring is on a spot:\nempty = BUILD, tower = UPGRADE\n\nTAP TO START');
elseif s.mode == 2
    m = sprintf('GRID OVERRUN\nYou reached wave %d', s.wave);
    if s.ann > 1
        m = [m newline newline 'TAP TO RETRY'];
    end
elseif s.ann > 0
    m = sprintf('WAVE %d   +$%d interest', s.wave, s.int);
    if mod(s.wave, 5) == 0
        m = [m '  -  BOSS!'];
    end
end
set(h.msg, 'String', m, 'Visible', V{1 + ~isempty(m)});
end

function p = ng(n, r, o)
% regular n-gon outline, radius r, first vertex at angle o
a = 2*pi*(0:n)/n + o;
p = r*[cos(a); sin(a)];
end

function p = st(n, r1, r2)
% n-pointed star
a = pi*(0:2*n)/n - pi/2;
p = [cos(a); sin(a)].*[repmat([r1 r2], 1, n) r1];
end
Play Game
Preview

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