07노이즈 속에 숨은 글자가 문턱을 올릴수록 또렷하게 떠오르는 확인
값 노이즈 장을 겹쳐 만들고 글자 마스크 안쪽에만 값을 살짝 올려 둔다. 문턱을 올리면 마스크 안쪽 화소가 먼저 남아 글자 모양이 드러난다.
쓰임노이즈 속 글자 찾기 확인·이미지 대체 문구 시연
THRESHNOISE_SCALEOCTAVESGRAIN
<main class="stage">
<div class="cp is-demo" id="cp">
<canvas class="cp__canvas" data-role="canvas" width="480" height="300" tabindex="0" aria-label="노이즈 속에 숨은 글자가 문턱을 올릴수록 또렷하게 떠오르는 확인"></canvas>
<p class="cp__status" data-role="status" aria-live="polite">시연 준비 중</p>
<button class="cp__btn" data-role="btn" type="button">멈춤</button>
</div>
</main>@use "../../../../site/static/demo-tokens" as *;
@include stage($stage-ink);
.cp {
position: relative;
width: min(92vw, calc(160vh - 12.8vw));
aspect-ratio: 480 / 300;
margin: 0 auto;
border-radius: $r-card;
overflow: hidden;
box-shadow: $shadow-raised;
background: $subject-ink;
}
.cp__canvas {
display: block;
width: 100%;
height: 100%;
touch-action: none;
}
.cp__canvas:focus-visible {
outline: 2px solid rgba(255, 255, 255, .85);
outline-offset: -6px;
}
.cp__status {
position: absolute;
left: $sp-3;
top: $sp-3;
max-width: 62%;
margin: 0;
padding: $sp-1 $sp-3;
border-radius: $r-pill;
background: rgba(255, 255, 255, .85);
color: $subject-ink;
font-weight: 500;
font-size: 11px;
line-height: 1.4;
pointer-events: none;
}
.cp__btn {
position: absolute;
right: $sp-3;
bottom: $sp-3;
margin: 0;
padding: $sp-1 $sp-3;
border: 0;
border-radius: $r-pill;
background: rgba(255, 255, 255, .85);
color: $subject-ink;
font-family: inherit;
font-weight: 500;
font-size: 12px;
line-height: 1.4;
cursor: pointer;
}
.cp__btn:focus-visible {
outline: 2px solid #ffffff;
outline-offset: 2px;
}
@media (max-width: 340px) {
.cp__btn { font-size: 10px; padding: $sp-1 $sp-2; }
.cp__status { font-size: 10px; }
}
@media (prefers-reduced-motion: reduce) {
.cp { cursor: default; }
}html, body {
margin: 0;
overflow: hidden;
}
.stage {
box-sizing: border-box;
min-height: 100vh;
display: grid;
place-items: center;
margin: 0;
background: #17141a;
font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
padding: clamp(8px, 4vw, 24px);
}
.cp {
position: relative;
width: min(92vw, 160vh - 12.8vw);
aspect-ratio: 480/300;
margin: 0 auto;
border-radius: 16px;
overflow: hidden;
box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
background: #17141a;
}
.cp__canvas {
display: block;
width: 100%;
height: 100%;
touch-action: none;
}
.cp__canvas:focus-visible {
outline: 2px solid rgba(255, 255, 255, 0.85);
outline-offset: -6px;
}
.cp__status {
position: absolute;
left: 12px;
top: 12px;
max-width: 62%;
margin: 0;
padding: 4px 12px;
border-radius: 999px;
background: rgba(255, 255, 255, 0.85);
color: #17141a;
font-weight: 500;
font-size: 11px;
line-height: 1.4;
pointer-events: none;
}
.cp__btn {
position: absolute;
right: 12px;
bottom: 12px;
margin: 0;
padding: 4px 12px;
border: 0;
border-radius: 999px;
background: rgba(255, 255, 255, 0.85);
color: #17141a;
font-family: inherit;
font-weight: 500;
font-size: 12px;
line-height: 1.4;
cursor: pointer;
}
.cp__btn:focus-visible {
outline: 2px solid #ffffff;
outline-offset: 2px;
}
@media (max-width: 340px) {
.cp__btn {
font-size: 10px;
padding: 4px 8px;
}
.cp__status {
font-size: 10px;
}
}
@media (prefers-reduced-motion: reduce) {
.cp {
cursor: default;
}
}(function () {
const root = document.getElementById("cp");
if (!root)
return;
const W = 480;
const H = 300;
const PI2 = Math.PI * 2;
const FIXED_DT = 16;
const IDLE_TICKS = 150;
const BTN_PAUSE = '멈춤';
const BTN_PLAY = '재생';
const BTN_NEXT = '다음 장면';
// 파스텔 팔레트 - 어두운 판 위에 밝은 색을 얹어 명도 차로 읽힌다
const BG = [29, 26, 44];
const PANEL = [44, 40, 68];
const MINT = [126, 226, 192];
const SKY = [124, 196, 255];
const LILAC = [190, 164, 255];
const PINK = [255, 160, 190];
const PEACH = [255, 208, 168];
const CREAM = [255, 244, 224];
const CHARSET = 'ABCDEFGHJKLMNPQRSTUVWXYZabdefghmnqrt23456789';
function clamp(v, lo, hi) { return v < lo ? lo : (v > hi ? hi : v); }
function lerp(a, b, k) { return a + (b - a) * k; }
function smooth(x) { const c = clamp(x, 0, 1); return c * c * (3 - 2 * c); }
function easeOutBack(x) { const c = clamp(x, 0, 1) - 1; return 1 + c * c * (2.7 * c + 1.7); }
function rgba(c, a) {
return 'rgba(' + Math.round(c[0]) + ',' + Math.round(c[1]) + ',' + Math.round(c[2]) + ',' + clamp(a, 0, 1).toFixed(3) + ')';
}
function mix(a, b, k) {
return [lerp(a[0], b[0], k), lerp(a[1], b[1], k), lerp(a[2], b[2], k)];
}
// 시드 고정 난수 - 같은 시드면 언제나 같은 수열 (선형 합동 방식)
function lcg(seed) {
let s = seed >>> 0;
return function () {
s = (Math.imul(s, 1664525) + 1013904223) >>> 0;
return s / 4294967296;
};
}
// 정수 두 개와 시드로 0 이상 1 미만의 값을 만드는 해시 (같은 입력은 늘 같은 값)
function hash2(x, y, seed) {
let h = (Math.imul(x | 0, 374761393) + Math.imul(y | 0, 668265263) + Math.imul(seed | 0, 1442695041)) | 0;
h = Math.imul(h ^ (h >>> 13), 1274126177);
h ^= h >>> 16;
return (h >>> 0) / 4294967296;
}
// 시드로 뜻 없는 글자열을 만든다
function glyphStr(seed, n) {
const r = lcg(seed * 7919 + 13);
let s = '';
for (let i = 0; i < n; i += 1) {
s += CHARSET.charAt(Math.floor(r() * CHARSET.length));
}
return s;
}
function rrect(ctx, x, y, w, h, r) {
const rr = Math.max(0, Math.min(r, w / 2, h / 2));
ctx.beginPath();
ctx.moveTo(x + rr, y);
ctx.lineTo(x + w - rr, y);
ctx.arcTo(x + w, y, x + w, y + rr, rr);
ctx.lineTo(x + w, y + h - rr);
ctx.arcTo(x + w, y + h, x + w - rr, y + h, rr);
ctx.lineTo(x + rr, y + h);
ctx.arcTo(x, y + h, x, y + h - rr, rr);
ctx.lineTo(x, y + rr);
ctx.arcTo(x, y, x + rr, y, rr);
ctx.closePath();
}
function mount(root, make) {
const canvas = root.querySelector('[data-role="canvas"]');
const statusEl = root.querySelector('[data-role="status"]');
const btnEl = root.querySelector('[data-role="btn"]');
if (!canvas || !statusEl || !btnEl) {
return function () { return; };
}
const ctx = canvas.getContext('2d');
if (!ctx) {
return function () { return; };
}
const dpr = Math.min(window.devicePixelRatio || 1, 2);
canvas.width = Math.round(W * dpr);
canvas.height = Math.round(H * dpr);
ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
const reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
const inp = { idle: 99999, focus: false, key: false };
const scene = make(inp, reduce);
let paused = false;
let rafId = 0;
let lastTs = -1;
let accMs = 0;
let lastLabel = '';
let lastLabelTick = -999;
let lastLive = 'polite';
let tickN = 0;
let clk = 0;
let wasAuto = true;
const cleaners = [];
function listen(target, type, fn) {
target.addEventListener(type, fn);
cleaners.push(function () { target.removeEventListener(type, fn); });
}
function show() {
scene.draw(ctx);
// 시연이 혼자 돌 때는 낭독을 끄고, 사람이 만지는 동안은 값이 바뀌어도 0.7초에 한 번만 갱신한다
const live = (reduce || inp.idle <= IDLE_TICKS) ? 'polite' : 'off';
if (live !== lastLive) {
lastLive = live;
statusEl.setAttribute('aria-live', live);
}
const t = scene.label();
if (t !== lastLabel && (reduce || live === 'off' || tickN - lastLabelTick >= 44)) {
lastLabel = t;
lastLabelTick = tickN;
statusEl.textContent = t;
}
}
// 고정 간격 한 틱 - 입력이 없으면 시연 스크립트가 같은 입구로 입력을 대신 넣는다
function advance() {
inp.idle += 1;
tickN += 1;
const a = inp.idle > IDLE_TICKS;
if (a && !wasAuto) {
scene.reset();
clk = 0;
}
wasAuto = a;
if (a) {
clk += 1;
scene.auto(clk);
if (clk >= scene.CYCLE) {
clk = 0;
scene.reset();
}
}
scene.step();
}
// 움직임 줄이기: 틱을 몰아서 돌린 뒤 한 번만 그린다 (중간 보간 장면은 화면에 나오지 않는다)
function settle(n) {
for (let i = 0; i < n; i += 1) {
inp.idle = 0;
tickN += 1;
scene.step();
}
show();
}
function tick(ts) {
if (lastTs < 0) {
lastTs = ts;
}
const frameDt = Math.min(ts - lastTs, 160);
lastTs = ts;
if (!paused) {
accMs += frameDt;
while (accMs >= FIXED_DT) {
advance();
accMs -= FIXED_DT;
}
show();
}
rafId = requestAnimationFrame(tick);
}
function point(e) {
const r = canvas.getBoundingClientRect();
return [clamp((e.clientX - r.left) * W / r.width, 0, W), clamp((e.clientY - r.top) * H / r.height, 0, H)];
}
btnEl.textContent = reduce ? BTN_NEXT : BTN_PAUSE;
if (reduce) {
root.classList.remove('is-demo');
for (let i = 0; i < scene.REDUCE_TICKS; i += 1) {
advance();
}
show();
}
listen(btnEl, 'click', function () {
if (reduce) {
if (scene.next) {
scene.next();
show();
return;
}
const n = Math.round(scene.CYCLE / 3);
inp.idle = 99999;
wasAuto = true;
for (let i = 0; i < n; i += 1) {
advance();
}
show();
return;
}
paused = !paused;
if (paused) {
root.classList.remove('is-demo');
}
else {
root.classList.add('is-demo');
}
btnEl.textContent = paused ? BTN_PLAY : BTN_PAUSE;
});
listen(canvas, 'focus', function () { inp.focus = true; if (reduce) {
show();
} });
listen(canvas, 'blur', function () { inp.focus = false; inp.key = false; if (reduce) {
show();
} });
listen(canvas, 'pointerdown', function (e) {
const p = point(e);
inp.idle = 0;
inp.key = false;
try {
canvas.setPointerCapture(e.pointerId);
}
catch (err) { /* 캡처가 안 되는 환경은 그냥 넘어간다 */ }
scene.down(p[0], p[1]);
if (reduce) {
settle(30);
}
});
listen(canvas, 'pointermove', function (e) {
const p = point(e);
inp.idle = 0;
inp.key = false;
scene.move(p[0], p[1]);
if (reduce) {
settle(30);
}
});
listen(canvas, 'pointerup', function (e) {
const p = point(e);
inp.idle = 0;
scene.up(p[0], p[1]);
if (reduce) {
settle(30);
}
});
listen(canvas, 'keydown', function (e) {
inp.idle = 0;
inp.key = true;
if (scene.key(e.key)) {
e.preventDefault();
}
if (reduce) {
settle(30);
}
});
if (!reduce) {
rafId = requestAnimationFrame(tick);
}
return function () {
cancelAnimationFrame(rafId);
for (let i = 0; i < cleaners.length; i += 1) {
cleaners[i]();
}
};
}
const THRESH = 0.86; // 글자가 가장 또렷한 문턱 (이 값 위쪽만 켜진다)
const NOISE_SCALE = 0.11; // 저해상도 화소 하나당 노이즈 좌표 증가량
const OCTAVES = 3; // 노이즈를 겹치는 층 수
const GRAIN = 0.045; // 문턱 주변 경계가 부드러워지는 폭
const BOOST = 0.42; // 글자 마스크 안쪽에만 더하는 값
const LW = 160;
const LH = 100;
const T_LOW = 0.36;
const GLYPH_N = 5;
const TXT_LIT = '문턱 {t} · 켜진 화소 글자 안 {a}% 바깥 {b}%';
// PURE-BEGIN
// 격자점 해시를 부드럽게 섞는 값 노이즈 (0 이상 1 미만)
function vnoise(x, y, seed) {
const xi = Math.floor(x);
const yi = Math.floor(y);
const fx = x - xi;
const fy = y - yi;
const u = fx * fx * (3 - 2 * fx);
const v = fy * fy * (3 - 2 * fy);
const a = hash2(xi, yi, seed);
const b = hash2(xi + 1, yi, seed);
const c = hash2(xi, yi + 1, seed);
const d = hash2(xi + 1, yi + 1, seed);
return a + (b - a) * u + (c - a) * v + (a - b - c + d) * u * v;
}
// 여러 층을 절반씩 줄여 가며 겹친 값 (0 이상 1 이하)
function fbm(x, y, seed, oct) {
let sum = 0;
let amp = 1;
let norm = 0;
let f = 1;
for (let o = 0; o < oct; o += 1) {
sum += amp * vnoise(x * f + o * 17.3, y * f - o * 9.1, seed + o);
norm += amp;
amp *= 0.5;
f *= 2;
}
return sum / norm;
}
// 값이 문턱을 넘은 정도를 0~1 로 (grain 폭 안에서 부드럽게 올라간다)
function litAmount(v, thresh, grain) {
const k = (v - thresh) / grain + 0.5;
return k <= 0 ? 0 : (k >= 1 ? 1 : k * k * (3 - 2 * k));
}
// PURE-END
const make = (inp, reduce) => {
const mk = document.createElement('canvas');
mk.width = LW;
mk.height = LH;
const mctx = mk.getContext('2d', { willReadFrequently: true });
const lo = document.createElement('canvas');
lo.width = LW;
lo.height = LH;
const lctx = lo.getContext('2d');
if (!mctx || !lctx) {
return { CYCLE: 1, REDUCE_TICKS: 0, reset() { return; }, auto() { return; }, step() { return; }, draw() { return; }, label() { return ''; }, down() { return; }, move() { return; }, up() { return; }, key() { return false; } };
}
const img = lctx.createImageData(LW, LH);
let mask = new Float32Array(LW * LH);
let maskTotal = 1;
let seed = 11;
let tNow = T_LOW;
let manual = false;
let mT = THRESH;
let t = 0;
let inPct = 0;
let outPct = 0;
function bakeMask() {
mctx.fillStyle = '#000';
mctx.fillRect(0, 0, LW, LH);
mctx.fillStyle = '#fff';
mctx.font = 'bold 50px "Segoe UI", "Noto Sans KR", sans-serif';
mctx.textAlign = 'center';
mctx.textBaseline = 'middle';
const s = glyphStr(seed + 90, GLYPH_N);
const stepX = (LW - 16) / GLYPH_N;
const r = lcg(seed * 19 + 3);
for (let i = 0; i < GLYPH_N; i += 1) {
mctx.save();
mctx.translate(8 + stepX * (i + 0.5), LH / 2 + (r() - 0.5) * 8);
mctx.rotate((r() - 0.5) * 0.3);
mctx.fillText(s.charAt(i), 0, 0);
mctx.restore();
}
const d = mctx.getImageData(0, 0, LW, LH).data;
mask = new Float32Array(LW * LH);
maskTotal = 0;
for (let i = 0; i < LW * LH; i += 1) {
mask[i] = d[i * 4] / 255;
maskTotal += mask[i] > 0.5 ? 1 : 0;
}
if (maskTotal < 1) {
maskTotal = 1;
}
}
bakeMask();
function curT() { return manual ? mT : tNow; }
const scene = {
CYCLE: 124,
REDUCE_TICKS: 80,
reset() { seed += 1; bakeMask(); manual = false; tNow = T_LOW; },
auto(clk) {
if (clk < 72) {
tNow = lerp(T_LOW, THRESH, smooth(clk / 72));
}
else if (clk < 100) {
tNow = THRESH;
}
else {
tNow = lerp(THRESH, T_LOW, smooth((clk - 100) / 22));
}
},
step() { t += 1; },
draw(ctx) {
const T = curT();
const o = img.data;
const dx = t * 0.35;
const dy = t * 0.18;
let litIn = 0;
let litOut = 0;
for (let y = 0; y < LH; y += 1) {
for (let x = 0; x < LW; x += 1) {
const i = y * LW + x;
const n = fbm(x * NOISE_SCALE + dx * NOISE_SCALE, y * NOISE_SCALE + dy * NOISE_SCALE, seed, OCTAVES);
const m = mask[i];
const v = n + m * BOOST;
const k = litAmount(v, T, GRAIN);
// 밝은 쪽 색 - 값이 클수록 연보라에서 하늘, 민트, 크림으로
const q = clamp((v - 0.3) / 0.9, 0, 1);
let c;
if (q < 0.45) {
c = mix(LILAC, SKY, q / 0.45);
}
else if (q < 0.8) {
c = mix(SKY, MINT, (q - 0.45) / 0.35);
}
else {
c = mix(MINT, CREAM, (q - 0.8) / 0.2);
}
const bg = mix(BG, PANEL, n * 0.9);
const j = i * 4;
o[j] = lerp(bg[0], c[0], k);
o[j + 1] = lerp(bg[1], c[1], k);
o[j + 2] = lerp(bg[2], c[2], k);
o[j + 3] = 255;
if (k > 0.5) {
if (m > 0.5) {
litIn += 1;
}
else {
litOut += 1;
}
}
}
}
lctx.putImageData(img, 0, 0);
ctx.imageSmoothingEnabled = true;
ctx.drawImage(lo, 0, 0, W, H);
inPct = Math.round(100 * litIn / maskTotal);
outPct = Math.round(100 * litOut / (LW * LH - maskTotal));
// 문턱 눈금
ctx.fillStyle = 'rgba(29,26,44,0.75)';
rrect(ctx, 14, H - 30, 132, 18, 9);
ctx.fill();
ctx.fillStyle = rgba(MINT, 1);
rrect(ctx, 18, H - 26, Math.max(6, 124 * clamp((T - 0.3) / 0.7, 0, 1)), 10, 5);
ctx.fill();
if (inp.key && inp.focus) {
ctx.strokeStyle = 'rgba(255,255,255,0.92)';
ctx.lineWidth = 2.5;
ctx.strokeRect(6, 6, W - 12, H - 12);
}
},
label() { return TXT_LIT.replace('{t}', (Math.round(curT() * 100) / 100).toFixed(2)).replace('{a}', String(inPct)).replace('{b}', String(outPct)); },
down() { manual = true; },
move(x) { manual = true; mT = lerp(0.3, 1.0, clamp(x / W, 0, 1)); },
up() { return; },
key(k) {
if (k === 'ArrowRight' || k === 'ArrowUp') {
manual = true;
mT = clamp(curT() + 0.04, 0.3, 1.0);
return true;
}
if (k === 'ArrowLeft' || k === 'ArrowDown') {
manual = true;
mT = clamp(curT() - 0.04, 0.3, 1.0);
return true;
}
if (k === 'Enter' || k === ' ') {
seed += 1;
bakeMask();
return true;
}
return false;
},
};
return scene;
};
return mount(root, make);
})();// CapNoiseFieldThresholdReveal - vanilla 판(07-cap-noise-field-threshold-reveal) 의 React 포트. 같은 계산을 useEffect 안에서 돌린다.
import { useEffect, useRef } from "react";
import styles from "./CapNoiseFieldThresholdReveal.module.scss";
const cx = (s: string): string => s.split(" ").map((n) => styles[n] ?? n).join(" ");
export default function CapNoiseFieldThresholdReveal() {
const rootRef = useRef<HTMLDivElement | null>(null);
useEffect(() => {
const root = rootRef.current;
if (!root) return;
type RGB = [number, number, number];
interface Input { idle: number; focus: boolean; key: boolean; }
interface Scene {
CYCLE: number;
REDUCE_TICKS: number;
reset(): void;
auto(clk: number): void;
step(): void;
draw(ctx: CanvasRenderingContext2D): void;
label(): string;
down(x: number, y: number): void;
move(x: number, y: number): void;
up(x: number, y: number): void;
key(k: string): boolean;
next?(): void;
}
type Make = (inp: Input, reduce: boolean) => Scene;
const W = 480;
const H = 300;
const PI2 = Math.PI * 2;
const FIXED_DT = 16;
const IDLE_TICKS = 150;
const BTN_PAUSE = '멈춤';
const BTN_PLAY = '재생';
const BTN_NEXT = '다음 장면';
// 파스텔 팔레트 - 어두운 판 위에 밝은 색을 얹어 명도 차로 읽힌다
const BG: RGB = [29, 26, 44];
const PANEL: RGB = [44, 40, 68];
const MINT: RGB = [126, 226, 192];
const SKY: RGB = [124, 196, 255];
const LILAC: RGB = [190, 164, 255];
const PINK: RGB = [255, 160, 190];
const PEACH: RGB = [255, 208, 168];
const CREAM: RGB = [255, 244, 224];
const CHARSET = 'ABCDEFGHJKLMNPQRSTUVWXYZabdefghmnqrt23456789';
function clamp(v: number, lo: number, hi: number): number { return v < lo ? lo : (v > hi ? hi : v); }
function lerp(a: number, b: number, k: number): number { return a + (b - a) * k; }
function smooth(x: number): number { const c = clamp(x, 0, 1); return c * c * (3 - 2 * c); }
function easeOutBack(x: number): number { const c = clamp(x, 0, 1) - 1; return 1 + c * c * (2.7 * c + 1.7); }
function rgba(c: RGB, a: number): string {
return 'rgba(' + Math.round(c[0]) + ',' + Math.round(c[1]) + ',' + Math.round(c[2]) + ',' + clamp(a, 0, 1).toFixed(3) + ')';
}
function mix(a: RGB, b: RGB, k: number): RGB {
return [lerp(a[0], b[0], k), lerp(a[1], b[1], k), lerp(a[2], b[2], k)];
}
// 시드 고정 난수 - 같은 시드면 언제나 같은 수열 (선형 합동 방식)
function lcg(seed: number): () => number {
let s = seed >>> 0;
return function () {
s = (Math.imul(s, 1664525) + 1013904223) >>> 0;
return s / 4294967296;
};
}
// 정수 두 개와 시드로 0 이상 1 미만의 값을 만드는 해시 (같은 입력은 늘 같은 값)
function hash2(x: number, y: number, seed: number): number {
let h = (Math.imul(x | 0, 374761393) + Math.imul(y | 0, 668265263) + Math.imul(seed | 0, 1442695041)) | 0;
h = Math.imul(h ^ (h >>> 13), 1274126177);
h ^= h >>> 16;
return (h >>> 0) / 4294967296;
}
// 시드로 뜻 없는 글자열을 만든다
function glyphStr(seed: number, n: number): string {
const r = lcg(seed * 7919 + 13);
let s = '';
for (let i = 0; i < n; i += 1) {
s += CHARSET.charAt(Math.floor(r() * CHARSET.length));
}
return s;
}
function rrect(ctx: CanvasRenderingContext2D, x: number, y: number, w: number, h: number, r: number): void {
const rr = Math.max(0, Math.min(r, w / 2, h / 2));
ctx.beginPath();
ctx.moveTo(x + rr, y);
ctx.lineTo(x + w - rr, y);
ctx.arcTo(x + w, y, x + w, y + rr, rr);
ctx.lineTo(x + w, y + h - rr);
ctx.arcTo(x + w, y + h, x + w - rr, y + h, rr);
ctx.lineTo(x + rr, y + h);
ctx.arcTo(x, y + h, x, y + h - rr, rr);
ctx.lineTo(x, y + rr);
ctx.arcTo(x, y, x + rr, y, rr);
ctx.closePath();
}
function mount(root: HTMLElement, make: Make): () => void {
const canvas = root.querySelector('[data-role="canvas"]') as HTMLCanvasElement;
const statusEl = root.querySelector('[data-role="status"]') as HTMLElement;
const btnEl = root.querySelector('[data-role="btn"]') as HTMLButtonElement;
if (!canvas || !statusEl || !btnEl) {
return function () { return; };
}
const ctx = canvas.getContext('2d') as CanvasRenderingContext2D;
if (!ctx) {
return function () { return; };
}
const dpr = Math.min(window.devicePixelRatio || 1, 2);
canvas.width = Math.round(W * dpr);
canvas.height = Math.round(H * dpr);
ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
const reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
const inp: Input = { idle: 99999, focus: false, key: false };
const scene = make(inp, reduce);
let paused = false;
let rafId = 0;
let lastTs = -1;
let accMs = 0;
let lastLabel = '';
let lastLabelTick = -999;
let lastLive = 'polite';
let tickN = 0;
let clk = 0;
let wasAuto = true;
const cleaners: Array<() => void> = [];
function listen<K extends keyof HTMLElementEventMap>(target: HTMLElement, type: K, fn: (e: HTMLElementEventMap[K]) => void): void {
target.addEventListener(type, fn);
cleaners.push(function () { target.removeEventListener(type, fn); });
}
function show(): void {
scene.draw(ctx);
// 시연이 혼자 돌 때는 낭독을 끄고, 사람이 만지는 동안은 값이 바뀌어도 0.7초에 한 번만 갱신한다
const live = (reduce || inp.idle <= IDLE_TICKS) ? 'polite' : 'off';
if (live !== lastLive) {
lastLive = live;
statusEl.setAttribute('aria-live', live);
}
const t = scene.label();
if (t !== lastLabel && (reduce || live === 'off' || tickN - lastLabelTick >= 44)) {
lastLabel = t;
lastLabelTick = tickN;
statusEl.textContent = t;
}
}
// 고정 간격 한 틱 - 입력이 없으면 시연 스크립트가 같은 입구로 입력을 대신 넣는다
function advance(): void {
inp.idle += 1;
tickN += 1;
const a = inp.idle > IDLE_TICKS;
if (a && !wasAuto) {
scene.reset();
clk = 0;
}
wasAuto = a;
if (a) {
clk += 1;
scene.auto(clk);
if (clk >= scene.CYCLE) {
clk = 0;
scene.reset();
}
}
scene.step();
}
// 움직임 줄이기: 틱을 몰아서 돌린 뒤 한 번만 그린다 (중간 보간 장면은 화면에 나오지 않는다)
function settle(n: number): void {
for (let i = 0; i < n; i += 1) {
inp.idle = 0;
tickN += 1;
scene.step();
}
show();
}
function tick(ts: number): void {
if (lastTs < 0) {
lastTs = ts;
}
const frameDt = Math.min(ts - lastTs, 160);
lastTs = ts;
if (!paused) {
accMs += frameDt;
while (accMs >= FIXED_DT) {
advance();
accMs -= FIXED_DT;
}
show();
}
rafId = requestAnimationFrame(tick);
}
function point(e: PointerEvent): number[] {
const r = canvas.getBoundingClientRect();
return [clamp((e.clientX - r.left) * W / r.width, 0, W), clamp((e.clientY - r.top) * H / r.height, 0, H)];
}
btnEl.textContent = reduce ? BTN_NEXT : BTN_PAUSE;
if (reduce) {
root.classList.remove('is-demo');
for (let i = 0; i < scene.REDUCE_TICKS; i += 1) {
advance();
}
show();
}
listen(btnEl, 'click', function () {
if (reduce) {
if (scene.next) {
scene.next();
show();
return;
}
const n = Math.round(scene.CYCLE / 3);
inp.idle = 99999;
wasAuto = true;
for (let i = 0; i < n; i += 1) {
advance();
}
show();
return;
}
paused = !paused;
if (paused) {
root.classList.remove('is-demo');
}
else {
root.classList.add('is-demo');
}
btnEl.textContent = paused ? BTN_PLAY : BTN_PAUSE;
});
listen(canvas, 'focus', function () { inp.focus = true; if (reduce) { show(); } });
listen(canvas, 'blur', function () { inp.focus = false; inp.key = false; if (reduce) { show(); } });
listen(canvas, 'pointerdown', function (e) {
const p = point(e);
inp.idle = 0;
inp.key = false;
try { canvas.setPointerCapture(e.pointerId); } catch (err) { /* 캡처가 안 되는 환경은 그냥 넘어간다 */ }
scene.down(p[0], p[1]);
if (reduce) { settle(30); }
});
listen(canvas, 'pointermove', function (e) {
const p = point(e);
inp.idle = 0;
inp.key = false;
scene.move(p[0], p[1]);
if (reduce) { settle(30); }
});
listen(canvas, 'pointerup', function (e) {
const p = point(e);
inp.idle = 0;
scene.up(p[0], p[1]);
if (reduce) { settle(30); }
});
listen(canvas, 'keydown', function (e) {
inp.idle = 0;
inp.key = true;
if (scene.key(e.key)) {
e.preventDefault();
}
if (reduce) { settle(30); }
});
if (!reduce) {
rafId = requestAnimationFrame(tick);
}
return function () {
cancelAnimationFrame(rafId);
for (let i = 0; i < cleaners.length; i += 1) {
cleaners[i]();
}
};
}
const THRESH = 0.86; // 글자가 가장 또렷한 문턱 (이 값 위쪽만 켜진다)
const NOISE_SCALE = 0.11; // 저해상도 화소 하나당 노이즈 좌표 증가량
const OCTAVES = 3; // 노이즈를 겹치는 층 수
const GRAIN = 0.045; // 문턱 주변 경계가 부드러워지는 폭
const BOOST = 0.42; // 글자 마스크 안쪽에만 더하는 값
const LW = 160;
const LH = 100;
const T_LOW = 0.36;
const GLYPH_N = 5;
const TXT_LIT = '문턱 {t} · 켜진 화소 글자 안 {a}% 바깥 {b}%';
// PURE-BEGIN
// 격자점 해시를 부드럽게 섞는 값 노이즈 (0 이상 1 미만)
function vnoise(x: number, y: number, seed: number): number {
const xi = Math.floor(x);
const yi = Math.floor(y);
const fx = x - xi;
const fy = y - yi;
const u = fx * fx * (3 - 2 * fx);
const v = fy * fy * (3 - 2 * fy);
const a = hash2(xi, yi, seed);
const b = hash2(xi + 1, yi, seed);
const c = hash2(xi, yi + 1, seed);
const d = hash2(xi + 1, yi + 1, seed);
return a + (b - a) * u + (c - a) * v + (a - b - c + d) * u * v;
}
// 여러 층을 절반씩 줄여 가며 겹친 값 (0 이상 1 이하)
function fbm(x: number, y: number, seed: number, oct: number): number {
let sum = 0;
let amp = 1;
let norm = 0;
let f = 1;
for (let o = 0; o < oct; o += 1) {
sum += amp * vnoise(x * f + o * 17.3, y * f - o * 9.1, seed + o);
norm += amp;
amp *= 0.5;
f *= 2;
}
return sum / norm;
}
// 값이 문턱을 넘은 정도를 0~1 로 (grain 폭 안에서 부드럽게 올라간다)
function litAmount(v: number, thresh: number, grain: number): number {
const k = (v - thresh) / grain + 0.5;
return k <= 0 ? 0 : (k >= 1 ? 1 : k * k * (3 - 2 * k));
}
// PURE-END
const make: Make = (inp, reduce) => {
const mk = document.createElement('canvas');
mk.width = LW;
mk.height = LH;
const mctx = mk.getContext('2d', { willReadFrequently: true }) as CanvasRenderingContext2D;
const lo = document.createElement('canvas');
lo.width = LW;
lo.height = LH;
const lctx = lo.getContext('2d') as CanvasRenderingContext2D;
if (!mctx || !lctx) {
return { CYCLE: 1, REDUCE_TICKS: 0, reset() { return; }, auto() { return; }, step() { return; }, draw() { return; }, label() { return ''; }, down() { return; }, move() { return; }, up() { return; }, key() { return false; } };
}
const img = lctx.createImageData(LW, LH);
let mask = new Float32Array(LW * LH);
let maskTotal = 1;
let seed = 11;
let tNow = T_LOW;
let manual = false;
let mT = THRESH;
let t = 0;
let inPct = 0;
let outPct = 0;
function bakeMask(): void {
mctx.fillStyle = '#000';
mctx.fillRect(0, 0, LW, LH);
mctx.fillStyle = '#fff';
mctx.font = 'bold 50px "Segoe UI", "Noto Sans KR", sans-serif';
mctx.textAlign = 'center';
mctx.textBaseline = 'middle';
const s = glyphStr(seed + 90, GLYPH_N);
const stepX = (LW - 16) / GLYPH_N;
const r = lcg(seed * 19 + 3);
for (let i = 0; i < GLYPH_N; i += 1) {
mctx.save();
mctx.translate(8 + stepX * (i + 0.5), LH / 2 + (r() - 0.5) * 8);
mctx.rotate((r() - 0.5) * 0.3);
mctx.fillText(s.charAt(i), 0, 0);
mctx.restore();
}
const d = mctx.getImageData(0, 0, LW, LH).data;
mask = new Float32Array(LW * LH);
maskTotal = 0;
for (let i = 0; i < LW * LH; i += 1) {
mask[i] = d[i * 4] / 255;
maskTotal += mask[i] > 0.5 ? 1 : 0;
}
if (maskTotal < 1) { maskTotal = 1; }
}
bakeMask();
function curT(): number { return manual ? mT : tNow; }
const scene: Scene = {
CYCLE: 124,
REDUCE_TICKS: 80,
reset() { seed += 1; bakeMask(); manual = false; tNow = T_LOW; },
auto(clk) {
if (clk < 72) { tNow = lerp(T_LOW, THRESH, smooth(clk / 72)); }
else if (clk < 100) { tNow = THRESH; }
else { tNow = lerp(THRESH, T_LOW, smooth((clk - 100) / 22)); }
},
step() { t += 1; },
draw(ctx) {
const T = curT();
const o = img.data;
const dx = t * 0.35;
const dy = t * 0.18;
let litIn = 0;
let litOut = 0;
for (let y = 0; y < LH; y += 1) {
for (let x = 0; x < LW; x += 1) {
const i = y * LW + x;
const n = fbm(x * NOISE_SCALE + dx * NOISE_SCALE, y * NOISE_SCALE + dy * NOISE_SCALE, seed, OCTAVES);
const m = mask[i];
const v = n + m * BOOST;
const k = litAmount(v, T, GRAIN);
// 밝은 쪽 색 - 값이 클수록 연보라에서 하늘, 민트, 크림으로
const q = clamp((v - 0.3) / 0.9, 0, 1);
let c: RGB;
if (q < 0.45) { c = mix(LILAC, SKY, q / 0.45); }
else if (q < 0.8) { c = mix(SKY, MINT, (q - 0.45) / 0.35); }
else { c = mix(MINT, CREAM, (q - 0.8) / 0.2); }
const bg = mix(BG, PANEL, n * 0.9);
const j = i * 4;
o[j] = lerp(bg[0], c[0], k);
o[j + 1] = lerp(bg[1], c[1], k);
o[j + 2] = lerp(bg[2], c[2], k);
o[j + 3] = 255;
if (k > 0.5) {
if (m > 0.5) { litIn += 1; } else { litOut += 1; }
}
}
}
lctx.putImageData(img, 0, 0);
ctx.imageSmoothingEnabled = true;
ctx.drawImage(lo, 0, 0, W, H);
inPct = Math.round(100 * litIn / maskTotal);
outPct = Math.round(100 * litOut / (LW * LH - maskTotal));
// 문턱 눈금
ctx.fillStyle = 'rgba(29,26,44,0.75)';
rrect(ctx, 14, H - 30, 132, 18, 9);
ctx.fill();
ctx.fillStyle = rgba(MINT, 1);
rrect(ctx, 18, H - 26, Math.max(6, 124 * clamp((T - 0.3) / 0.7, 0, 1)), 10, 5);
ctx.fill();
if (inp.key && inp.focus) {
ctx.strokeStyle = 'rgba(255,255,255,0.92)';
ctx.lineWidth = 2.5;
ctx.strokeRect(6, 6, W - 12, H - 12);
}
},
label() { return TXT_LIT.replace('{t}', (Math.round(curT() * 100) / 100).toFixed(2)).replace('{a}', String(inPct)).replace('{b}', String(outPct)); },
down() { manual = true; },
move(x) { manual = true; mT = lerp(0.3, 1.0, clamp(x / W, 0, 1)); },
up() { return; },
key(k) {
if (k === 'ArrowRight' || k === 'ArrowUp') { manual = true; mT = clamp(curT() + 0.04, 0.3, 1.0); return true; }
if (k === 'ArrowLeft' || k === 'ArrowDown') { manual = true; mT = clamp(curT() - 0.04, 0.3, 1.0); return true; }
if (k === 'Enter' || k === ' ') { seed += 1; bakeMask(); return true; }
return false;
},
};
return scene;
};
return mount(root, make);
}, []);
return (
<div className={cx("cp") + " is-demo"} id="cp" ref={rootRef}>
<canvas className={cx("cp__canvas")} data-role="canvas" width="480" height="300" tabIndex={0} aria-label="노이즈 속에 숨은 글자가 문턱을 올릴수록 또렷하게 떠오르는 확인"></canvas>
<p className={cx("cp__status")} data-role="status" aria-live="polite">시연 준비 중</p>
<button className={cx("cp__btn")} data-role="btn" type="button">멈춤</button>
</div>
);
}07 노이즈 속에 숨은 글자가 문턱을 올릴수록 또렷하게 떠오르는 확인 — 측정 누적면적 75.716% · 움직인 프레임 23/23GODRICH 원작 · zip 에 SCSS·React 포함 · css captcha 9가지 — 왜곡 글자·회전 맞추기·노이즈 속 글자 확인
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css captcha 9가지 — 왜곡 글자·회전 맞추기·노이즈 속 글자 확인css captcha 를 사람 확인이라 부르지만 화면이 하는 일은 계산이다 — 01번은 글자 열을 사인파로 밀고, 07번은 노이즈 문턱을 올려 숨은 글자를 건져 올린다. 여기 아홉 장면은 확인 화면이 어떻게 움직이는 이 글의 데모 전부 보기
