Custom Code Experiment •
Cossack
Source Code View HTML / CSS / JavaScript
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, viewport-fit=cover">
<title>Glitch Cossack dance loader</title>
<style>
:root {
box-sizing: border-box;
padding-top: env(safe-area-inset-top, 0px);
padding-bottom: env(safe-area-inset-bottom, 0px);
--page: #EDEDED;
--ring-track: rgba(0, 0, 0, 0.12);
--accent: #FFC21A;
--void: #0A0A0A;
}
@media (prefers-color-scheme: dark) {
:root:not([data-theme="light"]) {
--page: #141414;
--ring-track: rgba(255, 255, 255, 0.12);
}
}
:root[data-theme="dark"] {
--page: #141414;
--ring-track: rgba(255, 255, 255, 0.12);
}
*, *::before, *::after { box-sizing: inherit; }
html { height: 100%; scroll-padding-top: env(safe-area-inset-top, 0px); }
body {
margin: 0;
height: 100%;
background: var(--page);
display: grid;
place-items: center;
}
.orb {
position: relative;
width: min(260px, 70vw);
aspect-ratio: 1;
}
/* Animated yellow ring */
.ring {
position: absolute;
inset: 0;
width: 100%;
height: 100%;
transform: rotate(-90deg);
}
.ring circle { fill: none; stroke-width: 3; }
.ring .track { stroke: var(--ring-track); }
.ring .arc {
stroke: var(--accent);
stroke-linecap: round;
stroke-dasharray: 90 400;
animation: sweep 1.6s cubic-bezier(.6,.1,.3,.9) infinite;
transform-origin: 50% 50%;
}
@keyframes sweep {
0% { stroke-dasharray: 20 400; transform: rotate(0deg); }
50% { stroke-dasharray: 160 400; }
100% { stroke-dasharray: 20 400; transform: rotate(360deg); }
}
/* Circular viewport */
.window {
position: absolute;
inset: 12px;
border-radius: 50%;
overflow: hidden;
background: radial-gradient(circle at 50% 40%, #262626 0%, var(--void) 70%);
box-shadow: inset 0 0 40px rgba(0,0,0,.8), inset 0 0 0 1px rgba(255,255,255,.2);
}
.window canvas { display: block; width: 100%; height: 100%; }
/* spotlight from above */
.window::before {
content: "";
position: absolute;
inset: 0;
background: radial-gradient(ellipse 38% 70% at 50% 0%, rgba(255,255,255,.09), transparent 70%);
pointer-events: none;
}
/* scanlines */
.window::after {
content: "";
position: absolute;
inset: 0;
background: repeating-linear-gradient(to bottom, rgba(0,0,0,0) 0 2px, rgba(0,0,0,.28) 2px 3px);
pointer-events: none;
}
@media (prefers-reduced-motion: reduce) {
.ring .arc { animation-duration: 4s; }
}
</style>
</head>
<body>
<div class="orb" role="status" aria-label="Loading">
<svg class="ring" viewBox="0 0 100 100" aria-hidden="true">
<circle class="track" cx="50" cy="50" r="48"/>
<circle class="arc" cx="50" cy="50" r="48"/>
</svg>
<div class="window">
<canvas id="dancer" aria-hidden="true"></canvas>
</div>
</div>
<script>
(() => {
const canvas = document.getElementById('dancer');
const ctx = canvas.getContext('2d');
const buf = document.createElement('canvas');
const bctx = buf.getContext('2d');
const reduced = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
const WHITE = '#FFFFFF';
const FLOOR = '#8C8C8C';
const GHOST_A = '#8C8C8C', GHOST_B = '#E0E0E0';
let W = 0, H = 0, dpr = 1;
function resize() {
dpr = Math.min(window.devicePixelRatio || 1, 2);
const r = canvas.getBoundingClientRect();
W = Math.round(r.width * dpr); H = Math.round(r.height * dpr);
canvas.width = buf.width = W;
canvas.height = buf.height = H;
}
new ResizeObserver(resize).observe(canvas);
resize();
// ---------- Vector helpers ----------
const add = (a, b) => [a[0]+b[0], a[1]+b[1], a[2]+b[2]];
const mul = (a, k) => [a[0]*k, a[1]*k, a[2]*k];
const rotX = ([x, y, z], a) => [x, y*Math.cos(a) - z*Math.sin(a), y*Math.sin(a) + z*Math.cos(a)];
const rotY = ([x, y, z], a) => [x*Math.cos(a) + z*Math.sin(a), y, -x*Math.sin(a) + z*Math.cos(a)];
const rotZ = ([x, y, z], a) => [x*Math.cos(a) - y*Math.sin(a), x*Math.sin(a) + y*Math.cos(a), z];
// Limb direction: starts pointing down, raised sideways by `abd`, swung forward (+z) by `fwd`
const limbDir = (side, abd, fwd) => rotX(rotZ([0, -1, 0], side * abd), -fwd);
// ---------- Skeleton ----------
const SPINE = 0.72, NECK = 0.1, HEAD_R = 0.17;
const UPPER_ARM = 0.36, FOREARM = 0.34;
const THIGH = 0.44, SHIN = 0.44;
const FLOOR_Y = -1.0;
// ---------- Cossack dance (hopak) ----------
const s = Math.sin, c = Math.cos, PI = Math.PI, TAU = PI * 2;
const BPM = 116;
const sub = (a, b) => [a[0]-b[0], a[1]-b[1], a[2]-b[2]];
const dot = (a, b) => a[0]*b[0] + a[1]*b[1] + a[2]*b[2];
const len = (a) => Math.hypot(a[0], a[1], a[2]);
const norm = (a) => mul(a, 1 / (len(a) || 1));
const clamp = (v, a, b) => Math.min(b, Math.max(a, v));
const smooth = (x) => { x = clamp(x, 0, 1); return x * x * (3 - 2 * x); };
const lerp = (a, b, w) => a + (b - a) * w;
// Two-bone IK: the knee bends so the ankle reaches its target (or points straight at it if too far)
function ik(hip, target, a, b, hint) {
const toT = sub(target, hip);
const d = Math.min(a + b - 1e-4, Math.max(0.05, len(toT)));
const u = norm(toT);
const cosA = (a * a + d * d - b * b) / (2 * a * d);
const sinA = Math.sqrt(Math.max(0, 1 - cosA * cosA));
const n = norm(sub(hint, mul(u, dot(hint, u))));
return [add(hip, add(mul(u, a * cosA), mul(n, a * sinA))), add(hip, mul(u, d))];
}
// ---------- Gravity (same model as the Irish dancer) ----------
const G = 9.81 / 0.83; // figure ≈ 1.7 m tall, 1 unit ≈ 0.83 m
const secPerBeat = () => 60 / (reduced ? BPM / 3 : BPM);
function jump(b, period, height) {
const flight = Math.min(period * 0.75, Math.sqrt(8 * height / G) / secPerBeat());
const ground = period - flight;
const ph = ((b % period) + period) % period;
const takeoff = ground / 2, landing = takeoff + flight;
if (ph >= takeoff && ph <= landing) {
const u = (ph - takeoff) / flight;
return { air: 4 * height * u * (1 - u), u, flying: true, crouch: 0 };
}
const g = ph < takeoff ? ph + ground / 2 : ph - landing;
return { air: 0, u: 0, flying: false, crouch: s(PI * g / ground) };
}
// Feet are ankle targets in the body frame: x (side), y (height above floor), z (forward),
// plus `point`: 0 flat, + pointed toe, − flexed (heel down, toe up).
const foot = (x, y, z, point = 0) => ({ x, y, z, point });
const HIPS = { abd: 0.75, fwd: -0.1, eAbd: -1.6, eFwd: 0 }; // hands on hips
const CROSS_R = { abd: 0.3, fwd: 1.15, eAbd: -PI / 2 - 0.3, eFwd: -1.15 }; // arms folded at the chest
const CROSS_L = { abd: 0.3, fwd: 1.3, eAbd: -PI / 2 - 0.3, eFwd: -1.3 };
const OPEN = { abd: 1.45, fwd: 0.15, eAbd: 0.15, eFwd: 0 }; // arms flung out
const base = (o) => Object.assign({ hipH: 0.84, px: 0, air: 0, lean: 0, leanSide: 0, yaw: 0, headTurn: 0, headNod: 0, kneeOut: 0.3 }, o);
// 1. Stamping: hands on hips, knees lifting and stamping down on the beat
const stamp = (b) => {
const f = ((b % 1) + 1) % 1, k = s(PI * Math.pow(f, 0.8)); // lift, then drive down fast
const right = Math.floor(b) % 2 === 0;
const up = foot(0, 0.06 + 0.24 * k, 0.1 * k, 0.3 * k);
return base({
fR: right ? foot(0.13, up.y, up.z, up.point) : foot(0.13, 0.06, 0),
fL: right ? foot(-0.13, 0.06, 0) : foot(-0.13, up.y, up.z, up.point),
hipH: 0.83 - 0.03 * k, armR: HIPS, armL: HIPS, lean: -0.06,
yaw: 0.45 * s(b * PI / 4), headTurn: -0.3 * s(b * PI / 4)
});
};
// 2. Prisiadka: deep squat, arms folded, kicking legs out in turn with a little hop to switch
const prisiadka = (b) => {
const j = jump(b, 1, 0.05);
const kR = 0.5 + 0.5 * clamp(c(PI * b) * 3.5, -1, 1); // swaps legs mid-hop
const kL = 1 - kR;
const leg = (side, k) => foot(side * (0.15 + 0.03 * k), lerp(0.1, 0.06, k), lerp(0.05, 0.78, k), lerp(0.5, -0.6, k));
return base({
fR: leg(1, kR), fL: leg(-1, kL),
hipH: 0.3 - 0.03 * j.crouch, air: j.air,
armR: CROSS_R, armL: CROSS_L, lean: -0.12, headNod: -0.1, kneeOut: 0.6
});
};
// 3. Polzunets: feet planted wide, the body slides low from side to side,
// bending over one leg while the other stretches out straight, arms open
const polzunets = (b) => {
const side = c(b * PI / 2); // +1 over the right foot, −1 over the left
const px = 0.34 * side;
const bendR = (1 + side) / 2, bendL = 1 - bendR;
return base({
px, hipH: 0.34 + 0.1 * (1 - Math.abs(side)),
fR: foot(0.55, 0.06, 0.08, lerp(-0.6, 0.3, bendR)),
fL: foot(-0.55, 0.06, 0.08, lerp(-0.6, 0.3, bendL)),
armR: OPEN, armL: OPEN, leanSide: -0.22 * side, headTurn: -0.5 * side, kneeOut: 0.6
});
};
// 4. Straddle jumps: crouch, spring up, legs split wide to the sides, hands reaching for the toes
const straddle = (b) => {
const j = jump(b, 2, 0.55);
const sp = j.flying ? Math.min(1, s(PI * j.u) * 1.7) : 0;
const hipH = 0.84 - 0.3 * j.crouch;
const leg = (side) => foot(side * lerp(0.13, 0.85, sp), lerp(0.06, hipH + 0.05, sp), lerp(0, 0.28, sp), lerp(0, 0.9, sp));
const reach = { abd: lerp(0.3, 1.25, sp), fwd: lerp(0.2 + 0.6 * j.crouch, 0.5, sp), eAbd: 0, eFwd: lerp(0.3, 0, sp) };
return base({
fR: leg(1), fL: leg(-1), hipH, air: j.air,
armR: reach, armL: reach, lean: 0.25 * j.crouch + 0.35 * sp, headNod: -0.15 * sp, kneeOut: 0.35
});
};
const SCHEDULE = [[stamp, 8], [prisiadka, 8], [polzunets, 4], [straddle, 8]];
const TOTAL = SCHEDULE.reduce((n, [, l]) => n + l, 0);
function blend(a, b, w) {
if (typeof a === 'number') return a + (b - a) * w;
const o = {};
for (const k in a) o[k] = blend(a[k], b[k], w);
return o;
}
const FADE = 0.75; // time to drop into or rise out of the squat between steps
function poseAt(beat) {
let m = ((beat % TOTAL) + TOTAL) % TOTAL, i = 0;
while (m >= SCHEDULE[i][1]) { m -= SCHEDULE[i][1]; i++; }
const [fn, l] = SCHEDULE[i];
const cur = fn(m);
let p = cur;
if (m > l - FADE) {
const next = SCHEDULE[(i + 1) % SCHEDULE.length][0](m - l);
p = blend(cur, next, smooth((m - (l - FADE)) / FADE));
}
p.x = 0; p.z = 0;
return p;
}
const trails = { R: [], L: [] };
function buildTrails() { return []; }
function buildFigure(pose) {
const pelvisY = FLOOR_Y + pose.hipH + pose.air;
const pelvis = [pose.px, pelvisY, 0];
const hipR = [pose.px + 0.09, pelvisY, 0], hipL = [pose.px - 0.09, pelvisY, 0];
const ANK = 0.06;
const legPts = (hip, side, F) => {
const target = [F.x, FLOOR_Y + F.y + pose.air, F.z];
const hint = norm([side * pose.kneeOut, 0.15, 1]);
const [knee, ank] = ik(hip, target, THIGH, SHIN, hint);
const turn = side * 0.25;
const heel = add(ank, rotY([0, -ANK, -0.03], turn));
const toe = add(ank, rotY(rotX([0, -ANK, 0.14], F.point), turn));
return { knee, ank, heel, toe };
};
const LR = legPts(hipR, 1, pose.fR), LL = legPts(hipL, -1, pose.fL);
const up = rotZ(rotX([0, 1, 0], pose.lean), -pose.leanSide);
const neck = add(pelvis, mul(up, SPINE));
const shoulder = add(pelvis, mul(up, SPINE - 0.06));
const headOrient = (v) => rotZ(rotX(rotY(v, pose.headTurn), pose.lean + pose.headNod), -pose.leanSide);
const headC = add(neck, mul(headOrient([0, 1, 0]), NECK + HEAD_R));
const arm = (side, A) => {
const d1 = rotZ(rotX(limbDir(side, A.abd, A.fwd), 0), -pose.leanSide);
const elbow = add(shoulder, mul(d1, UPPER_ARM));
const d2 = rotZ(limbDir(side, A.abd + A.eAbd, A.fwd + A.eFwd), -pose.leanSide);
return [shoulder, elbow, add(elbow, mul(d2, FOREARM))];
};
const ar = arm(1, pose.armR), al = arm(-1, pose.armL);
const place = (p) => rotY(p, pose.yaw);
const polys = [];
const line = (pts, w = 2.4) => polys.push({ pts: pts.map(place), color: WHITE, w });
line([pelvis, neck]);
line([hipR, pelvis, hipL]);
line([add(shoulder, rotZ([0.1, 0, 0], -pose.leanSide)), shoulder, add(shoulder, rotZ([-0.1, 0, 0], -pose.leanSide))], 2.0);
line(ar); line(al);
line([hipR, LR.knee, LR.ank]); line([hipL, LL.knee, LL.ank]);
for (const L of [LR, LL]) line([L.ank, L.heel, L.toe, L.ank], 2.0); // boot
const headPt = (v) => place(add(headC, headOrient(v)));
for (const lat of [-0.5, 0, 0.5]) {
const pts = [], r = HEAD_R * c(lat), y = HEAD_R * s(lat);
for (let k = 0; k <= 18; k++) { const a = TAU * k / 18; pts.push(headPt([r * c(a), y, r * s(a)])); }
polys.push({ pts, color: WHITE, w: 1.2, dim: lat !== 0 });
}
for (let m = 0; m < 4; m++) {
const pts = [], a = PI * m / 4;
for (let k = 0; k <= 18; k++) { const q = TAU * k / 18; pts.push(headPt([HEAD_R * c(q) * c(a), HEAD_R * s(q), HEAD_R * c(q) * s(a)])); }
polys.push({ pts, color: WHITE, w: 1.0, dim: true });
}
// tall fur hat (papakha): a slightly flared cylinder
const hatY0 = HEAD_R * 0.55, hatH = 0.2;
const hatRing = (y, r) => {
const pts = [];
for (let k = 0; k <= 20; k++) { const a = TAU * k / 20; pts.push(headPt([r * c(a), y, r * s(a)])); }
return pts;
};
polys.push({ pts: hatRing(hatY0, 0.165), color: WHITE, w: 1.5 });
polys.push({ pts: hatRing(hatY0 + hatH * 0.5, 0.175), color: WHITE, w: 0.9, dim: true });
polys.push({ pts: hatRing(hatY0 + hatH, 0.185), color: WHITE, w: 1.5 });
for (let k = 0; k < 10; k++) {
const a = TAU * k / 10;
polys.push({ pts: [headPt([0.165 * c(a), hatY0, 0.165 * s(a)]), headPt([0.185 * c(a), hatY0 + hatH, 0.185 * s(a)])], color: WHITE, w: 0.9, dim: true });
}
for (const A of [ar, al]) {
const h = A[2], pts = [];
for (let k = 0; k <= 10; k++) { const a = TAU * k / 10; pts.push(place(add(h, [0.035 * c(a), 0.035 * s(a), 0]))); }
polys.push({ pts, color: WHITE, w: 1.2 });
}
return polys;
}
// Round wooden floor with boards; a ripple spreads on every beat (stamps and landings)
const FLOOR_R = 0.95;
let rippleBeat = 0;
function buildFloor() {
const polys = [], ring = [];
for (let k = 0; k <= 48; k++) { const a = TAU * k / 48; ring.push([FLOOR_R * c(a), FLOOR_Y, FLOOR_R * s(a)]); }
polys.push({ pts: ring, color: FLOOR, w: 1.1 });
for (let v = -0.8; v <= 0.81; v += 0.2) {
const h = Math.sqrt(FLOOR_R * FLOOR_R - v * v);
polys.push({ pts: [[-h, FLOOR_Y, v], [h, FLOOR_Y, v]], color: FLOOR, w: 0.7, dim: true });
}
const ph = ((rippleBeat % 1) + 1) % 1, r = 0.1 + ph * 0.5, pts = [];
for (let k = 0; k <= 32; k++) { const a = TAU * k / 32; pts.push([r * c(a), FLOOR_Y, r * s(a)]); }
polys.push({ pts, color: WHITE, w: 1.2, alpha: (1 - ph) * 0.7 });
return polys;
}
// ---------- Projection ----------
// The camera follows the dancer, so he stays centred and the floor glides beneath him
const CENTER_Y = 0.3;
let focusX = 0, focusZ = 0;
function project(p, view, jitter) {
let [x, y, z] = p;
x -= focusX; y -= CENTER_Y; z -= focusZ;
if (jitter) { x += (Math.random()-.5)*jitter; y += (Math.random()-.5)*jitter; }
const cy = Math.cos(view.yaw), sy = Math.sin(view.yaw);
const x1 = x * cy + z * sy, z1 = -x * sy + z * cy;
const cx = Math.cos(view.pitch), sx = Math.sin(view.pitch);
const y1 = y * cx - z1 * sx, z2 = y * sx + z1 * cx;
const d = 5, persp = d / (d - z2);
const scale = W * 0.235;
return [W/2 + x1 * scale * persp, H/2 - y1 * scale * persp, z2];
}
function strokeAll(polys, view, color, alpha, ox, oy, jitter) {
for (const poly of polys) {
bctx.beginPath();
let depthSum = 0;
poly.pts.forEach((p, i) => {
const [sx, sy, sz] = project(p, view, jitter);
depthSum += sz;
if (i === 0) bctx.moveTo(sx + ox, sy + oy); else bctx.lineTo(sx + ox, sy + oy);
});
const depth = depthSum / poly.pts.length;
const fade = 0.45 + 0.55 * Math.min(1, Math.max(0, (depth + 1.2) / 2.4));
bctx.globalAlpha = alpha * fade * (poly.dim ? 0.55 : 1) * (poly.alpha ?? 1);
bctx.strokeStyle = color || poly.color;
bctx.lineWidth = poly.w * dpr;
bctx.stroke();
}
bctx.globalAlpha = 1;
}
// ---------- Loop ----------
let glitch = 0, glitchStrength = 0;
let orbit = 0, last = performance.now();
let beatShift = 0;
function frame(now) {
if (W === 0 || H === 0) {
resize();
if (W === 0 || H === 0) { last = now; requestAnimationFrame(frame); return; }
}
const dt = Math.min(50, now - last) / 1000; last = now;
orbit += dt * (reduced ? 0.15 : 0.45);
const t = now / 1000;
let beat = t * (reduced ? BPM / 3 : BPM) / 60;
if (!reduced && glitch <= 0 && Math.random() < 0.025) {
glitch = 4 + Math.floor(Math.random() * 10);
glitchStrength = 0.4 + Math.random() * 0.6;
beatShift = Math.random() < 0.5 ? -Math.random() * 0.4 : 0; // the dancer skips back, time keeps flowing
}
const g = glitch > 0;
if (g) glitch--; else beatShift = 0;
beat += beatShift;
const view = { yaw: orbit, pitch: 0.22 + Math.sin(t * 0.7) * 0.04 };
const pose = poseAt(beat);
focusX = 0; focusZ = 0; rippleBeat = beat;
const polys = buildFloor().concat(buildFigure(pose));
bctx.clearRect(0, 0, W, H);
bctx.lineJoin = 'round'; bctx.lineCap = 'round';
bctx.globalCompositeOperation = 'lighter';
if (g) {
const off = (4 + Math.random() * 8) * dpr * glitchStrength;
strokeAll(polys, view, GHOST_A, 0.7, -off, 0, 0.03 * glitchStrength);
strokeAll(polys, view, GHOST_B, 0.6, off, (Math.random()-.5)*2*dpr, 0.03 * glitchStrength);
}
strokeAll(polys, view, null, g ? 0.85 : 1, 0, 0, g ? 0.02 : (reduced ? 0 : 0.004));
bctx.globalCompositeOperation = 'source-over';
ctx.clearRect(0, 0, W, H);
if (g) {
let y = 0;
while (y < H) {
const h = Math.min(H - y, Math.max(2, Math.floor((4 + Math.random() * 30) * dpr)));
const shift = Math.random() < 0.35 ? (Math.random() - .5) * 40 * dpr * glitchStrength : 0;
ctx.drawImage(buf, 0, y, W, h, shift, y, W, h);
y += h;
}
const blocks = Math.floor(Math.random() * 4);
for (let i = 0; i < blocks; i++) {
ctx.fillStyle = [WHITE, GHOST_A, GHOST_B][i % 3];
ctx.globalAlpha = 0.18 + Math.random() * 0.3;
ctx.fillRect(Math.random() * W, Math.random() * H, (10 + Math.random() * 60) * dpr, (1 + Math.random() * 3) * dpr);
}
ctx.globalAlpha = 1;
} else {
ctx.drawImage(buf, 0, 0);
}
requestAnimationFrame(frame);
}
requestAnimationFrame(frame);
})();
</script>
</body>
</html>