04Trail Particles That Scatter With Air Drag and Noise Behind the Flight
It drops a particle at each point on the flight path, multiplies its velocity by an air drag factor every frame, and pushes it along directions read from a 2D noise field so it drifts apart like smoke.
Best forNewsletter sign-ups and invitation sends
TRAIL_COUNTAIR_DRAGTRAIL_NOISE
<main class="stage">
<div class="sb is-demo" id="sb">
<div class="sb__scene" data-role="scene">
<canvas class="sb__canvas" data-role="canvas" width="480" height="300" aria-hidden="true"></canvas>
<button class="tr__send" data-role="send" type="button"><svg xmlns="http://www.w3.org/2000/svg" class="tr__icon" data-role="icon" aria-hidden="true" focusable="false" viewBox="0 0 256 256"><g fill="currentColor"><path d="m223.69 42.18l-58.22 192a8 8 0 0 1-14.92 1.25L108 148l-87.42-42.55a8 8 0 0 1 1.25-14.92l192-58.22a8 8 0 0 1 9.86 9.87" opacity=".2"/><path d="M227.32 28.68a16 16 0 0 0-15.66-4.08h-.15L19.57 82.84a16 16 0 0 0-2.49 29.8L102 154l41.3 84.87a15.86 15.86 0 0 0 14.44 9.13q.69 0 1.38-.06a15.88 15.88 0 0 0 14-11.51l58.2-191.94v-.15a16 16 0 0 0-4-15.66m-69.49 203.17l-.05.14v-.07l-40.06-82.3l48-48a8 8 0 0 0-11.31-11.31l-48 48l-82.33-40.06h-.07h.14L216 40Z"/></g></svg><span class="tr__label" data-role="label">Send invite</span></button>
<p class="sb__status sb__status--top" data-role="status" aria-live="off">Ready to send</p>
</div>
</div>
</main>@use "../../../../site/static/demo-tokens" as *;
@include stage($stage-paper);
.sb {
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;
}
// 장면 판 — 480×300 좌표로 짜 두고 스크립트가 상자 폭에 맞춰 scale 한다.
// 기준점이 왼쪽 위 모서리인 이유: 판이 상자 왼쪽 위에 붙어 있어 모서리 기준으로 줄여야 줄인 판이 상자와 겹친다
.sb__scene {
position: absolute;
left: 0;
top: 0;
width: 480px;
height: 300px;
transform-origin: 0 0;
}
.sb__canvas {
position: absolute;
left: 0;
top: 0;
width: 480px;
height: 300px;
pointer-events: none;
}
.sb__status {
position: absolute;
left: $sp-4;
bottom: $sp-3;
box-sizing: border-box;
max-width: 260px;
margin: 0;
padding: $sp-1 $sp-3;
border-radius: $r-pill;
background: rgba(255, 255, 255, .9);
color: $subject-ink;
font-weight: 500;
font-size: 12px;
line-height: 1.4;
pointer-events: none;
}
.sb__status--top {
top: $sp-3;
bottom: auto;
}
.sb__status--side {
max-width: 140px;
border-radius: $r-control;
}
.sb { background: #262035; }
// 버튼 안 아이콘 가운데 = 스크립트 PATH 첫 점 (66, 236) — 왼쪽 40 + 안쪽 여백 16 + 아이콘 절반 11
.tr__send {
position: absolute;
left: 40px;
top: 212px;
width: 192px;
height: 48px;
margin: 0;
padding: 0 $sp-4;
border: 0;
border-radius: $r-pill;
background: #c8b8ff;
color: $subject-ink;
font: inherit;
font-weight: 700;
font-size: 15px;
line-height: 1;
display: flex;
align-items: center;
gap: $sp-2;
cursor: pointer;
}
.tr__send.is-sent { background: #b4ecd9; }
.tr__send:focus-visible {
outline: 3px solid #ffffff;
outline-offset: 3px;
}
.tr__icon {
width: 22px;
height: 22px;
flex: none;
}
@media (max-width: 340px) {
// 이 폭에서는 장면이 0.6 배 남짓으로 줄어든다 — 상태 줄 글자를 키워 줄인 뒤에도 읽히게 한다
.sb__status { font-size: 16px; }
}
@media (prefers-reduced-motion: reduce) {
// 움직임은 전부 스크립트가 그리고, 스크립트는 reduce 에서 루프를 돌리지 않고 결과 상태만 둔다. CSS 쪽 전환도 막아 둔다
.sb__scene * {
transition: none !important;
animation: none !important;
}
}html, body {
margin: 0;
overflow: hidden;
}
.stage {
box-sizing: border-box;
min-height: 100vh;
display: grid;
place-items: center;
margin: 0;
background: #ffffff;
font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
padding: clamp(8px, 4vw, 24px);
}
.sb {
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);
}
.sb__scene {
position: absolute;
left: 0;
top: 0;
width: 480px;
height: 300px;
transform-origin: 0 0;
}
.sb__canvas {
position: absolute;
left: 0;
top: 0;
width: 480px;
height: 300px;
pointer-events: none;
}
.sb__status {
position: absolute;
left: 16px;
bottom: 12px;
box-sizing: border-box;
max-width: 260px;
margin: 0;
padding: 4px 12px;
border-radius: 999px;
background: rgba(255, 255, 255, 0.9);
color: #17141a;
font-weight: 500;
font-size: 12px;
line-height: 1.4;
pointer-events: none;
}
.sb__status--top {
top: 12px;
bottom: auto;
}
.sb__status--side {
max-width: 140px;
border-radius: 12px;
}
.sb {
background: #262035;
}
.tr__send {
position: absolute;
left: 40px;
top: 212px;
width: 192px;
height: 48px;
margin: 0;
padding: 0 16px;
border: 0;
border-radius: 999px;
background: #c8b8ff;
color: #17141a;
font: inherit;
font-weight: 700;
font-size: 15px;
line-height: 1;
display: flex;
align-items: center;
gap: 8px;
cursor: pointer;
}
.tr__send.is-sent {
background: #b4ecd9;
}
.tr__send:focus-visible {
outline: 3px solid #ffffff;
outline-offset: 3px;
}
.tr__icon {
width: 22px;
height: 22px;
flex: none;
}
@media (max-width: 340px) {
.sb__status {
font-size: 16px;
}
}
@media (prefers-reduced-motion: reduce) {
.sb__scene * {
transition: none !important;
animation: none !important;
}
}(function () {
const root = document.getElementById("sb");
if (!root) return;
const W = 480;
const H = 300;
const FIXED_DT = 16;
// 파스텔 팔레트 — 캔버스와 스크립트가 칠하는 색은 여기서만 고른다 (scss 쪽 색은 demo-tokens)
const INK = [38, 33, 52];
const PAPER = [255, 252, 246];
const CREAM = [255, 243, 224];
const SKY = [158, 208, 255];
const LILAC = [200, 184, 255];
const MINT = [156, 228, 204];
const PINK = [255, 182, 204];
const PEACH = [255, 214, 184];
function clamp(v, lo, hi) { return v < lo ? lo : (v > hi ? hi : v); }
function lerp(a, b, t) { return a + (b - a) * t; }
function easeOut(x) { const c = clamp(x, 0, 1); return 1 - Math.pow(1 - c, 3); }
function easeInOut(x) {
const c = clamp(x, 0, 1);
return c < 0.5 ? 4 * c * c * c : 1 - Math.pow(-2 * c + 2, 3) / 2;
}
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, t) { return [lerp(a[0], b[0], t), lerp(a[1], b[1], t), lerp(a[2], b[2], t)]; }
// 시드 고정 난수 — 같은 시드면 같은 값이 다시 나온다 (32비트 정수 섞기)
function makeRng(seed) {
let s = seed >>> 0;
return function () {
s = (s + 0x6d2b79f5) >>> 0;
let t = s;
t = Math.imul(t ^ (t >>> 15), t | 1);
t ^= t + Math.imul(t ^ (t >>> 7), t | 61);
return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
};
}
const sceneEl = root.querySelector('[data-role="scene"]');
const statusEl = root.querySelector('[data-role="status"]');
if (!sceneEl || !statusEl) {
return;
}
const scene = sceneEl;
const status = statusEl;
const reduceQuery = window.matchMedia('(prefers-reduced-motion: reduce)');
const still = reduceQuery.matches;
const resizeHooks = [];
// 자동 시연 중인가 — 사람이 처음 만지는 순간 시연을 멈추고 처음 상태로 돌린 뒤 상태 줄을 읽어 주기 시작한다
let demo = root.classList.contains('is-demo');
function wake() {
if (!demo) {
return;
}
demo = false;
root.classList.remove('is-demo');
status.setAttribute('aria-live', 'polite');
resetIdle();
}
function say(text) {
if (status.textContent !== text) {
status.textContent = text;
}
}
// 장면 배율 — 480×300 좌표로 짠 판을 상자 폭에 맞춰 통째로 줄인다
let k = 1;
function fitScene() {
const w = root.clientWidth;
k = w > 0 ? w / W : 1;
scene.style.transform = 'scale(' + k.toFixed(4) + ')';
}
// 화면 좌표(CSS px) → 장면 좌표(480×300). 줄인 배율 k 로 나눠야 판 안의 위치가 된다
function toScene(clientX, clientY) {
const r = root.getBoundingClientRect();
return [(clientX - r.left) / k, (clientY - r.top) / k];
}
// 캡처 단계에서 듣는다 — 버튼 자신의 pointerdown 보다 먼저 시연을 끝내야 사람의 첫 누름이 처음 상태에서 시작한다
root.addEventListener('pointerdown', wake, true);
root.addEventListener('keydown', wake, true);
const canvasEl = root.querySelector('[data-role="canvas"]');
const ctxRaw = canvasEl ? canvasEl.getContext('2d') : null;
if (!canvasEl || !ctxRaw) {
return;
}
const cv = canvasEl;
const ctx = ctxRaw;
let dprNow = 1;
function fitCanvas() {
// 배율은 2 에서 자른다 — 배율 3 기기에서 화소가 2.25배로 늘어 프레임마다 일이 그만큼 커지지 않게
const dpr = Math.min(window.devicePixelRatio || 1, 2);
dprNow = dpr;
cv.width = Math.round(W * dpr);
cv.height = Math.round(H * dpr);
ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
}
fitCanvas();
resizeHooks.push(fitCanvas);
// 2D 값 노이즈 — 격자점마다 시드 난수 값을 두고 사이를 부드럽게 보간한다. 결과는 -1~1
function makeNoise(seed) {
const rng = makeRng(seed);
const perm = new Uint8Array(512);
const vals = new Float32Array(256);
for (let i = 0; i < 256; i += 1) {
vals[i] = rng() * 2 - 1;
perm[i] = i;
}
for (let i = 255; i > 0; i -= 1) {
const j = Math.floor(rng() * (i + 1));
const t = perm[i];
perm[i] = perm[j];
perm[j] = t;
}
for (let i = 0; i < 256; i += 1) {
perm[i + 256] = perm[i];
}
function at(xi, yi) { return vals[perm[(xi & 255) + perm[yi & 255]]]; }
return function (x, y) {
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 = lerp(at(xi, yi), at(xi + 1, yi), u);
const b = lerp(at(xi, yi + 1), at(xi + 1, yi + 1), u);
return lerp(a, b, v);
};
}
// 꼬리 입자 풀 크기 — 이 수를 넘으면 가장 오래된 입자 자리부터 다시 쓴다
const TRAIL_COUNT = 150;
// 공기 저항 — 16ms 한 걸음마다 속도에 곱한다. 1 에 가까울수록 멀리 미끄러진다
const AIR_DRAG = 0.955;
// 노이즈 장이 입자를 미는 세기(px/걸음²). 장의 값이 방향(0~2π)이 된다
const TRAIL_NOISE = 0.06;
const NOISE_SCALE = 0.011;
const NOISE_DRIFT = 0.00045;
const LIFE_MS = 1100;
const SPAWN_PER_STEP = 3;
const FLY_MS = 1150;
const DEMO_CYCLE = 2400;
// 비행 경로 — 버튼 안 아이콘 자리에서 출발하는 3차 베지어 S 곡선
const PATH = [[66, 236], [250, 96], [318, 270], [520, 58]];
// 날아가는 종이비행기 모양 = 버튼 아이콘과 같은 Phosphor paper-plane-tilt 경로(256 격자)
const PLANE_FILL = 'm223.69 42.18l-58.22 192a8 8 0 0 1-14.92 1.25L108 148l-87.42-42.55a8 8 0 0 1 1.25-14.92l192-58.22a8 8 0 0 1 9.86 9.87';
const PLANE_LINE = 'M227.32 28.68a16 16 0 0 0-15.66-4.08h-.15L19.57 82.84a16 16 0 0 0-2.49 29.8L102 154l41.3 84.87a15.86 15.86 0 0 0 14.44 9.13q.69 0 1.38-.06a15.88 15.88 0 0 0 14-11.51l58.2-191.94v-.15a16 16 0 0 0-4-15.66m-69.49 203.17l-.05.14v-.07l-40.06-82.3l48-48a8 8 0 0 0-11.31-11.31l-48 48l-82.33-40.06h-.07h.14L216 40Z';
const TXT_IDLE = 'Send invite';
const TXT_SENDING = 'Sending';
const TXT_SENT = 'Sent';
const TXT_READY = 'Ready to send';
const TXT_FLY = 'Flying off with a trail';
const TXT_DONE = 'Sent — the invite is on its way';
const sendEl = root.querySelector('[data-role="send"]');
const labelEl = root.querySelector('[data-role="label"]');
const iconEl = root.querySelector('[data-role="icon"]');
if (!sendEl || !labelEl || !iconEl) {
return;
}
const send = sendEl;
const label = labelEl;
const icon = iconEl;
const planeFill = new Path2D(PLANE_FILL);
const planeLine = new Path2D(PLANE_LINE);
const noise = makeNoise(466);
const rng = makeRng(4660);
const px = new Float32Array(TRAIL_COUNT);
const py = new Float32Array(TRAIL_COUNT);
const vx = new Float32Array(TRAIL_COUNT);
const vy = new Float32Array(TRAIL_COUNT);
const age = new Float32Array(TRAIL_COUNT);
const alive = new Uint8Array(TRAIL_COUNT);
let head = 0;
let phase = 'idle';
let pt = 0;
let fieldT = 0;
let demoNext = 200;
function pathAt(t) {
const u = 1 - t;
const a = u * u * u, b = 3 * u * u * t, c = 3 * u * t * t, d = t * t * t;
return [a * PATH[0][0] + b * PATH[1][0] + c * PATH[2][0] + d * PATH[3][0], a * PATH[0][1] + b * PATH[1][1] + c * PATH[2][1] + d * PATH[3][1]];
}
function pathDir(t) {
const u = 1 - t;
const dx = 3 * u * u * (PATH[1][0] - PATH[0][0]) + 6 * u * t * (PATH[2][0] - PATH[1][0]) + 3 * t * t * (PATH[3][0] - PATH[2][0]);
const dy = 3 * u * u * (PATH[1][1] - PATH[0][1]) + 6 * u * t * (PATH[2][1] - PATH[1][1]) + 3 * t * t * (PATH[3][1] - PATH[2][1]);
const l = Math.hypot(dx, dy) || 1;
return [dx / l, dy / l];
}
function flyParam(p) { return Math.pow(clamp(p, 0, 1), 1.3); }
// 입자 하나를 꼬리 자리에 떨어뜨린다 — 진행 반대쪽으로 조금, 옆으로 시드 난수만큼 흩뿌린다
function spawn(pos, dir) {
const i = head;
head = (head + 1) % TRAIL_COUNT;
const side = (rng() - 0.5) * 0.9;
const back = 0.6 + rng() * 0.8;
px[i] = pos[0] - dir[0] * 8;
py[i] = pos[1] - dir[1] * 8;
vx[i] = -dir[0] * back - dir[1] * side;
vy[i] = -dir[1] * back + dir[0] * side;
age[i] = 0;
alive[i] = 1;
}
// 한 걸음 — 속도에 저항을 곱해 줄이고, 그 자리 노이즈 값이 가리키는 방향으로 민 뒤 옮긴다
function advance(i) {
vx[i] *= AIR_DRAG;
vy[i] *= AIR_DRAG;
const ang = noise(px[i] * NOISE_SCALE, py[i] * NOISE_SCALE + fieldT * NOISE_DRIFT) * Math.PI * 2;
vx[i] += Math.cos(ang) * TRAIL_NOISE;
vy[i] += Math.sin(ang) * TRAIL_NOISE - 0.004;
px[i] += vx[i];
py[i] += vy[i];
age[i] += FIXED_DT;
if (age[i] >= LIFE_MS) {
alive[i] = 0;
}
}
function aliveCount() {
let n = 0;
for (let i = 0; i < TRAIL_COUNT; i += 1) {
n += alive[i];
}
return n;
}
function setIcon(a, s) {
icon.style.opacity = a === 1 ? '' : a.toFixed(3);
icon.style.transform = s === 1 ? '' : 'scale(' + s.toFixed(3) + ')';
}
function resetIdle() {
phase = 'idle';
pt = 0;
alive.fill(0);
label.textContent = TXT_IDLE;
send.classList.remove('is-sent');
setIcon(1, 1);
say(TXT_READY);
}
function finish() {
phase = 'done';
pt = 0;
alive.fill(0);
label.textContent = TXT_SENT;
send.classList.add('is-sent');
setIcon(1, 1);
say(TXT_DONE);
}
function settle() { finish(); }
function press() {
if (phase !== 'idle' && phase !== 'done') {
return;
}
if (still) {
finish();
return;
}
resetIdle();
phase = 'fly';
label.textContent = TXT_SENDING;
setIcon(0, 1);
say(TXT_FLY);
}
function step() {
fieldT += FIXED_DT;
for (let i = 0; i < TRAIL_COUNT; i += 1) {
if (alive[i] === 1) {
advance(i);
}
}
if (phase === 'idle' || phase === 'done') {
return;
}
pt += FIXED_DT;
if (phase === 'fly') {
const t = flyParam(pt / FLY_MS);
const pos = pathAt(t);
const dir = pathDir(t);
if (pos[0] < W + 10) {
for (let s = 0; s < SPAWN_PER_STEP; s += 1) {
spawn(pos, dir);
}
}
if (pt >= FLY_MS) {
phase = 'drift';
pt = 0;
label.textContent = TXT_SENT;
send.classList.add('is-sent');
}
}
else if (phase === 'drift' && aliveCount() === 0) {
finish();
}
}
function demoTick(t) {
if (t < demoNext) {
return;
}
demoNext += DEMO_CYCLE;
resetIdle();
press();
}
function draw() {
ctx.clearRect(0, 0, W, H);
for (let i = 0; i < TRAIL_COUNT; i += 1) {
if (alive[i] === 0) {
continue;
}
const f = age[i] / LIFE_MS;
ctx.fillStyle = rgba(mix(LILAC, SKY, f), 0.5 * Math.pow(1 - f, 1.3));
ctx.beginPath();
ctx.arc(px[i], py[i], 1.5 + 5 * f, 0, Math.PI * 2);
ctx.fill();
}
if (phase === 'fly') {
const t = flyParam(pt / FLY_MS);
const pos = pathAt(t);
const dir = pathDir(t);
ctx.save();
ctx.translate(pos[0], pos[1]);
// 아이콘 기수는 오른쪽 위(−45°)를 본다 — 진행 각도에 45° 를 더해 기수를 접선에 맞춘다
ctx.rotate(Math.atan2(dir[1], dir[0]) + Math.PI / 4);
ctx.scale(26 / 256, 26 / 256);
ctx.translate(-128, -128);
ctx.fillStyle = rgba(PAPER, 0.55);
ctx.fill(planeFill);
ctx.fillStyle = rgba(PAPER, 1);
ctx.fill(planeLine);
ctx.restore();
}
else if (phase === 'drift') {
const p = clamp(pt / 260, 0, 1);
setIcon(p, lerp(0.4, 1, easeOut(p)));
}
}
send.addEventListener('click', function () { press(); });
resetIdle();
let rafId = 0;
let lastTs = -1;
let acc = 0;
let clock = 0;
function onResize() {
fitScene();
for (const f of resizeHooks) {
f();
}
draw();
}
fitScene();
window.addEventListener('resize', onResize);
function frame(ts) {
if (lastTs < 0) {
lastTs = ts;
}
// 탭이 숨었다 돌아와도 한 번에 100ms 까지만 따라잡는다 — 순간이동 대신 이어서 움직인다
acc += Math.min(ts - lastTs, 100);
lastTs = ts;
let n = 0;
while (acc >= FIXED_DT && n < 6) {
clock += FIXED_DT;
if (demo) {
demoTick(clock);
}
step();
acc -= FIXED_DT;
n += 1;
}
draw();
rafId = window.requestAnimationFrame(frame);
}
if (still) {
settle();
draw();
}
else {
rafId = window.requestAnimationFrame(frame);
}
return function () {
window.cancelAnimationFrame(rafId);
window.removeEventListener('resize', onResize);
};
})();// SendTrailDragNoise - vanilla 판(04-send-btn-trail-drag-noise) 의 React 포트. 같은 계산을 useEffect 안에서 돌린다.
import { useEffect, useRef } from "react";
import styles from "./SendTrailDragNoise.module.scss";
const cx = (s: string): string => s.split(" ").map((n) => styles[n] ?? n).join(" ");
export default function SendTrailDragNoise() {
const rootRef = useRef<HTMLDivElement | null>(null);
useEffect(() => {
const rootEl = rootRef.current;
if (!rootEl) return;
const root: HTMLElement = rootEl;
type RGB = [number, number, number];
const W = 480;
const H = 300;
const FIXED_DT = 16;
// 파스텔 팔레트 — 캔버스와 스크립트가 칠하는 색은 여기서만 고른다 (scss 쪽 색은 demo-tokens)
const INK: RGB = [38, 33, 52];
const PAPER: RGB = [255, 252, 246];
const CREAM: RGB = [255, 243, 224];
const SKY: RGB = [158, 208, 255];
const LILAC: RGB = [200, 184, 255];
const MINT: RGB = [156, 228, 204];
const PINK: RGB = [255, 182, 204];
const PEACH: RGB = [255, 214, 184];
function clamp(v: number, lo: number, hi: number): number { return v < lo ? lo : (v > hi ? hi : v); }
function lerp(a: number, b: number, t: number): number { return a + (b - a) * t; }
function easeOut(x: number): number { const c = clamp(x, 0, 1); return 1 - Math.pow(1 - c, 3); }
function easeInOut(x: number): number {
const c = clamp(x, 0, 1);
return c < 0.5 ? 4 * c * c * c : 1 - Math.pow(-2 * c + 2, 3) / 2;
}
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, t: number): RGB { return [lerp(a[0], b[0], t), lerp(a[1], b[1], t), lerp(a[2], b[2], t)]; }
// 시드 고정 난수 — 같은 시드면 같은 값이 다시 나온다 (32비트 정수 섞기)
function makeRng(seed: number): () => number {
let s = seed >>> 0;
return function (): number {
s = (s + 0x6d2b79f5) >>> 0;
let t = s;
t = Math.imul(t ^ (t >>> 15), t | 1);
t ^= t + Math.imul(t ^ (t >>> 7), t | 61);
return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
};
}
const sceneEl = root.querySelector('[data-role="scene"]') as HTMLElement | null;
const statusEl = root.querySelector('[data-role="status"]') as HTMLElement | null;
if (!sceneEl || !statusEl) { return; }
const scene: HTMLElement = sceneEl;
const status: HTMLElement = statusEl;
const reduceQuery = window.matchMedia('(prefers-reduced-motion: reduce)');
const still = reduceQuery.matches;
const resizeHooks: Array<() => void> = [];
// 자동 시연 중인가 — 사람이 처음 만지는 순간 시연을 멈추고 처음 상태로 돌린 뒤 상태 줄을 읽어 주기 시작한다
let demo = root.classList.contains('is-demo');
function wake(): void {
if (!demo) { return; }
demo = false;
root.classList.remove('is-demo');
status.setAttribute('aria-live', 'polite');
resetIdle();
}
function say(text: string): void {
if (status.textContent !== text) { status.textContent = text; }
}
// 장면 배율 — 480×300 좌표로 짠 판을 상자 폭에 맞춰 통째로 줄인다
let k = 1;
function fitScene(): void {
const w = root.clientWidth;
k = w > 0 ? w / W : 1;
scene.style.transform = 'scale(' + k.toFixed(4) + ')';
}
// 화면 좌표(CSS px) → 장면 좌표(480×300). 줄인 배율 k 로 나눠야 판 안의 위치가 된다
function toScene(clientX: number, clientY: number): [number, number] {
const r = root.getBoundingClientRect();
return [(clientX - r.left) / k, (clientY - r.top) / k];
}
// 캡처 단계에서 듣는다 — 버튼 자신의 pointerdown 보다 먼저 시연을 끝내야 사람의 첫 누름이 처음 상태에서 시작한다
root.addEventListener('pointerdown', wake, true);
root.addEventListener('keydown', wake, true);
const canvasEl = root.querySelector('[data-role="canvas"]') as HTMLCanvasElement | null;
const ctxRaw = canvasEl ? canvasEl.getContext('2d') : null;
if (!canvasEl || !ctxRaw) { return; }
const cv: HTMLCanvasElement = canvasEl;
const ctx: CanvasRenderingContext2D = ctxRaw;
let dprNow = 1;
function fitCanvas(): void {
// 배율은 2 에서 자른다 — 배율 3 기기에서 화소가 2.25배로 늘어 프레임마다 일이 그만큼 커지지 않게
const dpr = Math.min(window.devicePixelRatio || 1, 2);
dprNow = dpr;
cv.width = Math.round(W * dpr);
cv.height = Math.round(H * dpr);
ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
}
fitCanvas();
resizeHooks.push(fitCanvas);
// 2D 값 노이즈 — 격자점마다 시드 난수 값을 두고 사이를 부드럽게 보간한다. 결과는 -1~1
function makeNoise(seed: number): (x: number, y: number) => number {
const rng = makeRng(seed);
const perm = new Uint8Array(512);
const vals = new Float32Array(256);
for (let i = 0; i < 256; i += 1) { vals[i] = rng() * 2 - 1; perm[i] = i; }
for (let i = 255; i > 0; i -= 1) {
const j = Math.floor(rng() * (i + 1));
const t = perm[i];
perm[i] = perm[j];
perm[j] = t;
}
for (let i = 0; i < 256; i += 1) { perm[i + 256] = perm[i]; }
function at(xi: number, yi: number): number { return vals[perm[(xi & 255) + perm[yi & 255]]]; }
return function (x: number, y: 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 = lerp(at(xi, yi), at(xi + 1, yi), u);
const b = lerp(at(xi, yi + 1), at(xi + 1, yi + 1), u);
return lerp(a, b, v);
};
}
type Phase = 'idle' | 'fly' | 'drift' | 'done';
type V2 = [number, number];
// 꼬리 입자 풀 크기 — 이 수를 넘으면 가장 오래된 입자 자리부터 다시 쓴다
const TRAIL_COUNT = 150;
// 공기 저항 — 16ms 한 걸음마다 속도에 곱한다. 1 에 가까울수록 멀리 미끄러진다
const AIR_DRAG = 0.955;
// 노이즈 장이 입자를 미는 세기(px/걸음²). 장의 값이 방향(0~2π)이 된다
const TRAIL_NOISE = 0.06;
const NOISE_SCALE = 0.011;
const NOISE_DRIFT = 0.00045;
const LIFE_MS = 1100;
const SPAWN_PER_STEP = 3;
const FLY_MS = 1150;
const DEMO_CYCLE = 2400;
// 비행 경로 — 버튼 안 아이콘 자리에서 출발하는 3차 베지어 S 곡선
const PATH: V2[] = [[66, 236], [250, 96], [318, 270], [520, 58]];
// 날아가는 종이비행기 모양 = 버튼 아이콘과 같은 Phosphor paper-plane-tilt 경로(256 격자)
const PLANE_FILL = 'm223.69 42.18l-58.22 192a8 8 0 0 1-14.92 1.25L108 148l-87.42-42.55a8 8 0 0 1 1.25-14.92l192-58.22a8 8 0 0 1 9.86 9.87';
const PLANE_LINE = 'M227.32 28.68a16 16 0 0 0-15.66-4.08h-.15L19.57 82.84a16 16 0 0 0-2.49 29.8L102 154l41.3 84.87a15.86 15.86 0 0 0 14.44 9.13q.69 0 1.38-.06a15.88 15.88 0 0 0 14-11.51l58.2-191.94v-.15a16 16 0 0 0-4-15.66m-69.49 203.17l-.05.14v-.07l-40.06-82.3l48-48a8 8 0 0 0-11.31-11.31l-48 48l-82.33-40.06h-.07h.14L216 40Z';
const TXT_IDLE = '초대장 보내기';
const TXT_SENDING = '보내는 중';
const TXT_SENT = '보냈어요';
const TXT_READY = '보낼 준비 됨';
const TXT_FLY = '꼬리를 남기며 날아가는 중';
const TXT_DONE = '보냄 — 초대장이 출발했어요';
const sendEl = root.querySelector('[data-role="send"]') as HTMLButtonElement | null;
const labelEl = root.querySelector('[data-role="label"]') as HTMLElement | null;
const iconEl = root.querySelector('[data-role="icon"]') as SVGElement | null;
if (!sendEl || !labelEl || !iconEl) { return; }
const send: HTMLButtonElement = sendEl;
const label: HTMLElement = labelEl;
const icon: SVGElement = iconEl;
const planeFill = new Path2D(PLANE_FILL);
const planeLine = new Path2D(PLANE_LINE);
const noise = makeNoise(466);
const rng = makeRng(4660);
const px = new Float32Array(TRAIL_COUNT);
const py = new Float32Array(TRAIL_COUNT);
const vx = new Float32Array(TRAIL_COUNT);
const vy = new Float32Array(TRAIL_COUNT);
const age = new Float32Array(TRAIL_COUNT);
const alive = new Uint8Array(TRAIL_COUNT);
let head = 0;
let phase: Phase = 'idle';
let pt = 0;
let fieldT = 0;
let demoNext = 200;
function pathAt(t: number): V2 {
const u = 1 - t;
const a = u * u * u, b = 3 * u * u * t, c = 3 * u * t * t, d = t * t * t;
return [a * PATH[0][0] + b * PATH[1][0] + c * PATH[2][0] + d * PATH[3][0], a * PATH[0][1] + b * PATH[1][1] + c * PATH[2][1] + d * PATH[3][1]];
}
function pathDir(t: number): V2 {
const u = 1 - t;
const dx = 3 * u * u * (PATH[1][0] - PATH[0][0]) + 6 * u * t * (PATH[2][0] - PATH[1][0]) + 3 * t * t * (PATH[3][0] - PATH[2][0]);
const dy = 3 * u * u * (PATH[1][1] - PATH[0][1]) + 6 * u * t * (PATH[2][1] - PATH[1][1]) + 3 * t * t * (PATH[3][1] - PATH[2][1]);
const l = Math.hypot(dx, dy) || 1;
return [dx / l, dy / l];
}
function flyParam(p: number): number { return Math.pow(clamp(p, 0, 1), 1.3); }
// 입자 하나를 꼬리 자리에 떨어뜨린다 — 진행 반대쪽으로 조금, 옆으로 시드 난수만큼 흩뿌린다
function spawn(pos: V2, dir: V2): void {
const i = head;
head = (head + 1) % TRAIL_COUNT;
const side = (rng() - 0.5) * 0.9;
const back = 0.6 + rng() * 0.8;
px[i] = pos[0] - dir[0] * 8;
py[i] = pos[1] - dir[1] * 8;
vx[i] = -dir[0] * back - dir[1] * side;
vy[i] = -dir[1] * back + dir[0] * side;
age[i] = 0;
alive[i] = 1;
}
// 한 걸음 — 속도에 저항을 곱해 줄이고, 그 자리 노이즈 값이 가리키는 방향으로 민 뒤 옮긴다
function advance(i: number): void {
vx[i] *= AIR_DRAG;
vy[i] *= AIR_DRAG;
const ang = noise(px[i] * NOISE_SCALE, py[i] * NOISE_SCALE + fieldT * NOISE_DRIFT) * Math.PI * 2;
vx[i] += Math.cos(ang) * TRAIL_NOISE;
vy[i] += Math.sin(ang) * TRAIL_NOISE - 0.004;
px[i] += vx[i];
py[i] += vy[i];
age[i] += FIXED_DT;
if (age[i] >= LIFE_MS) { alive[i] = 0; }
}
function aliveCount(): number {
let n = 0;
for (let i = 0; i < TRAIL_COUNT; i += 1) { n += alive[i]; }
return n;
}
function setIcon(a: number, s: number): void {
icon.style.opacity = a === 1 ? '' : a.toFixed(3);
icon.style.transform = s === 1 ? '' : 'scale(' + s.toFixed(3) + ')';
}
function resetIdle(): void {
phase = 'idle';
pt = 0;
alive.fill(0);
label.textContent = TXT_IDLE;
send.classList.remove('is-sent');
setIcon(1, 1);
say(TXT_READY);
}
function finish(): void {
phase = 'done';
pt = 0;
alive.fill(0);
label.textContent = TXT_SENT;
send.classList.add('is-sent');
setIcon(1, 1);
say(TXT_DONE);
}
function settle(): void { finish(); }
function press(): void {
if (phase !== 'idle' && phase !== 'done') { return; }
if (still) { finish(); return; }
resetIdle();
phase = 'fly';
label.textContent = TXT_SENDING;
setIcon(0, 1);
say(TXT_FLY);
}
function step(): void {
fieldT += FIXED_DT;
for (let i = 0; i < TRAIL_COUNT; i += 1) { if (alive[i] === 1) { advance(i); } }
if (phase === 'idle' || phase === 'done') { return; }
pt += FIXED_DT;
if (phase === 'fly') {
const t = flyParam(pt / FLY_MS);
const pos = pathAt(t);
const dir = pathDir(t);
if (pos[0] < W + 10) { for (let s = 0; s < SPAWN_PER_STEP; s += 1) { spawn(pos, dir); } }
if (pt >= FLY_MS) {
phase = 'drift';
pt = 0;
label.textContent = TXT_SENT;
send.classList.add('is-sent');
}
} else if (phase === 'drift' && aliveCount() === 0) {
finish();
}
}
function demoTick(t: number): void {
if (t < demoNext) { return; }
demoNext += DEMO_CYCLE;
resetIdle();
press();
}
function draw(): void {
ctx.clearRect(0, 0, W, H);
for (let i = 0; i < TRAIL_COUNT; i += 1) {
if (alive[i] === 0) { continue; }
const f = age[i] / LIFE_MS;
ctx.fillStyle = rgba(mix(LILAC, SKY, f), 0.5 * Math.pow(1 - f, 1.3));
ctx.beginPath();
ctx.arc(px[i], py[i], 1.5 + 5 * f, 0, Math.PI * 2);
ctx.fill();
}
if (phase === 'fly') {
const t = flyParam(pt / FLY_MS);
const pos = pathAt(t);
const dir = pathDir(t);
ctx.save();
ctx.translate(pos[0], pos[1]);
// 아이콘 기수는 오른쪽 위(−45°)를 본다 — 진행 각도에 45° 를 더해 기수를 접선에 맞춘다
ctx.rotate(Math.atan2(dir[1], dir[0]) + Math.PI / 4);
ctx.scale(26 / 256, 26 / 256);
ctx.translate(-128, -128);
ctx.fillStyle = rgba(PAPER, 0.55);
ctx.fill(planeFill);
ctx.fillStyle = rgba(PAPER, 1);
ctx.fill(planeLine);
ctx.restore();
} else if (phase === 'drift') {
const p = clamp(pt / 260, 0, 1);
setIcon(p, lerp(0.4, 1, easeOut(p)));
}
}
send.addEventListener('click', function (): void { press(); });
resetIdle();
let rafId = 0;
let lastTs = -1;
let acc = 0;
let clock = 0;
function onResize(): void {
fitScene();
for (const f of resizeHooks) { f(); }
draw();
}
fitScene();
window.addEventListener('resize', onResize);
function frame(ts: number): void {
if (lastTs < 0) { lastTs = ts; }
// 탭이 숨었다 돌아와도 한 번에 100ms 까지만 따라잡는다 — 순간이동 대신 이어서 움직인다
acc += Math.min(ts - lastTs, 100);
lastTs = ts;
let n = 0;
while (acc >= FIXED_DT && n < 6) {
clock += FIXED_DT;
if (demo) { demoTick(clock); }
step();
acc -= FIXED_DT;
n += 1;
}
draw();
rafId = window.requestAnimationFrame(frame);
}
if (still) {
settle();
draw();
} else {
rafId = window.requestAnimationFrame(frame);
}
return function (): void {
window.cancelAnimationFrame(rafId);
window.removeEventListener('resize', onResize);
};
}, []);
return (
<div className={cx("sb") + " is-demo"} ref={rootRef}>
<div className={cx("sb__scene")} data-role="scene">
<canvas className={cx("sb__canvas")} data-role="canvas" width={480} height={300} aria-hidden="true"></canvas>
<button className={cx("tr__send")} data-role="send" type="button"><svg xmlns="http://www.w3.org/2000/svg" className={cx("tr__icon")} data-role="icon" aria-hidden="true" focusable="false" viewBox="0 0 256 256"><g fill="currentColor"><path d="m223.69 42.18l-58.22 192a8 8 0 0 1-14.92 1.25L108 148l-87.42-42.55a8 8 0 0 1 1.25-14.92l192-58.22a8 8 0 0 1 9.86 9.87" opacity=".2"/><path d="M227.32 28.68a16 16 0 0 0-15.66-4.08h-.15L19.57 82.84a16 16 0 0 0-2.49 29.8L102 154l41.3 84.87a15.86 15.86 0 0 0 14.44 9.13q.69 0 1.38-.06a15.88 15.88 0 0 0 14-11.51l58.2-191.94v-.15a16 16 0 0 0-4-15.66m-69.49 203.17l-.05.14v-.07l-40.06-82.3l48-48a8 8 0 0 0-11.31-11.31l-48 48l-82.33-40.06h-.07h.14L216 40Z"/></g></svg><span className={cx("tr__label")} data-role="label">초대장 보내기</span></button>
<p className={cx("sb__status sb__status--top")} data-role="status" aria-live="off">보낼 준비 됨</p>
</div>
</div>
);
}04 Trail Particles That Scatter With Air Drag and Noise Behind the Flight — Measured area 14.133% · moving frames 22/23Original by GODRICH · SCSS and React ship in the zip · Send Button Animation CSS: 9 Fold-and-Fly Buttons
The post this demo lives in
Send Button Animation CSS: 9 Fold-and-Fly ButtonsA send button should show that something left — 01 folds into a paper plane that banks along a curve, 02 springs back as See all demos in this post
If you like this effect - similar demos
Buttons09 Disabled ripple block — pressing a button whose disabled value is on stops the ripple-spread value midway and answers with a shake value insteadButton Group CSS: 9 Adjoined Patterns
Buttons04 Liquid-metal Button That Merges and Spreads With a Pointer-distance ValueButton Click Effect CSS: 9 Canvas Pixel Patterns
Buttons02 Button that unlocks when the form is valid9 button state css patterns, loading to done