07Loader a Ripple-radius Value Spreads Across a Spring Mesh

<main class="stage">
<div class="ld" id="ld">
  <p class="ld__hint">
    <svg class="ld__ico" viewBox="0 0 256 256" aria-hidden="true"><g fill="currentColor"><path d="M232 56v56a8 8 0 0 1-16 0V91.3l-25.6 25.7A80 80 0 1 1 174 60a8 8 0 1 1-9 13.2A64 64 0 1 0 179.7 128H216a8 8 0 0 1 0 16h-56a8 8 0 0 1-8-8V80a8 8 0 0 1 16 0v20.7L192.7 76A80.1 80.1 0 0 0 64 128a8 8 0 0 1-16 0a96 96 0 0 1 163.6-68.3L224 71.3V56a8 8 0 0 1 8 8" opacity=".2"/><path d="M224 48a8 8 0 0 0-8 8v15.3l-11.7-11.6a96 96 0 1 0 27.6 51.6a8 8 0 0 0-15.8 2.5a80 80 0 1 1-23-43l-25.7 25.7A8 8 0 0 0 173 112h56a8 8 0 0 0 8-8V56a8 8 0 0 0-13-8"/></g></svg>
    <span>Click or press the space bar to pause or restart</span>
  </p>
  <div class="ld__field" id="field" role="application" aria-label="Spring mesh ripple test panel" tabindex="0">
    <canvas class="ld__cv" id="cv"></canvas>
    <b class="ld__badge" aria-hidden="true"><span class="ld__badgeNum" id="pct">0%</span><span class="ld__badgeUnit">Ripple</span></b>
  </div>
</div>
</main>

@use "../../../../site/static/demo-tokens" as *;

// 스프링 격자 로더 — 파동 반경이 번지며 닿은 격자점마다 감쇠 스프링(강성 상수 STIFFNESS)으로 튕긴다.
// 움직임은 전부 캔버스 rAF 루프 안에 있다. CSS 는 무대·판·배지만 맡는다(@keyframes 0개 — 077 선례와 같은 이유).

$duration: $dur-loop;
$easing: $ease-pop;
$color: $subject-orange-deep;

@include stage($stage-orange);

.ld {
  --paper: #{$subject-cream};
  --line: #{rgba($subject-ink, .22)};
  --node: #{rgba($subject-ink, .38)};
  --node-hot: #{$subject-orange-deep};
  --ring: #{rgba($subject-orange-deep, .3)};

  display: flex; flex-direction: column; gap: $sp-2;
  width: 100%; max-width: 424px;
}

.ld__hint {
  display: flex; align-items: center; gap: $sp-1; margin: 0;
  font-weight: 700; font-size: clamp(10px, 2.8vw, 12px); line-height: 1.35;
  color: $subject-ink;
}
.ld__ico { width: 16px; height: 16px; flex: 0 0 auto; color: $subject-orange-deep; }

.ld__field {
  position: relative; height: 208px;
  border-radius: $r-card; overflow: hidden;
  background: $subject-cream;
  box-shadow: inset 0 0 0 1px rgba($subject-ink, .16);
  cursor: pointer;
}
.ld__field:focus-visible { outline: 2px solid $subject-orange-deep; outline-offset: 2px; }

.ld__cv { display: block; width: 100%; height: 100%; }

.ld__badge {
  position: absolute; right: $sp-2; top: $sp-2;
  display: flex; align-items: baseline; gap: $sp-1;
  padding: $sp-1 $sp-2; border-radius: $r-pill;
  background: rgba($subject-ink, .78);
  color: $subject-cream; font-weight: 700; font-size: 11px;
}
.ld__badgeNum { font-size: 13px; color: $stage-yellow; }
.ld__badgeUnit { font-weight: 700; }

@media (max-width: 340px) {
  .ld { gap: $sp-1; }
  .ld__field { height: 124px; }
  .ld__badge { font-size: 10px; padding: 0 $sp-1; }
  .ld__badgeNum { font-size: 11px; }
}

// reduce — 루프를 시작하지 않고 진행률 62% 언저리에서 멈춘 한 장만 그린다.
@media (prefers-reduced-motion: reduce) {
  .ld.is-still .ld__field { cursor: default !important; }
  .ld.is-still .ld__badge { opacity: .92 !important; }
}

html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ff4d1f;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.ld {
  --paper: #fff7e6;
  --line: rgba(23, 20, 26, 0.22);
  --node: rgba(23, 20, 26, 0.38);
  --node-hot: #c93000;
  --ring: rgba(201, 48, 0, 0.3);
  display: flex;
  flex-direction: column;
  gap: 8px;
  width: 100%;
  max-width: 424px;
}

.ld__hint {
  display: flex;
  align-items: center;
  gap: 4px;
  margin: 0;
  font-weight: 700;
  font-size: clamp(10px, 2.8vw, 12px);
  line-height: 1.35;
  color: #17141a;
}

.ld__ico {
  width: 16px;
  height: 16px;
  flex: 0 0 auto;
  color: #c93000;
}

.ld__field {
  position: relative;
  height: 208px;
  border-radius: 16px;
  overflow: hidden;
  background: #fff7e6;
  box-shadow: inset 0 0 0 1px rgba(23, 20, 26, 0.16);
  cursor: pointer;
}

.ld__field:focus-visible {
  outline: 2px solid #c93000;
  outline-offset: 2px;
}

.ld__cv {
  display: block;
  width: 100%;
  height: 100%;
}

.ld__badge {
  position: absolute;
  right: 8px;
  top: 8px;
  display: flex;
  align-items: baseline;
  gap: 4px;
  padding: 4px 8px;
  border-radius: 999px;
  background: rgba(23, 20, 26, 0.78);
  color: #fff7e6;
  font-weight: 700;
  font-size: 11px;
}

.ld__badgeNum {
  font-size: 13px;
  color: #ffd23f;
}

.ld__badgeUnit {
  font-weight: 700;
}

@media (max-width: 340px) {
  .ld {
    gap: 4px;
  }
  .ld__field {
    height: 124px;
  }
  .ld__badge {
    font-size: 10px;
    padding: 0 4px;
  }
  .ld__badgeNum {
    font-size: 11px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .ld.is-still .ld__field {
    cursor: default !important;
  }
  .ld.is-still .ld__badge {
    opacity: 0.92 !important;
  }
}

// 스프링 격자 로더 — Ripple 반경이 중심에서 바깥으로 번지고, 파동이 각 격자점에 닿는 순간
// 그 점은 감쇠 스프링(강성 상수 spring-mesh-stiffness, 닫힌해 SHM)으로 튕겼다가 가라앉는다.
var root = document.getElementById('ld');
var field = document.getElementById('field');
var cv = document.getElementById('cv');
var ctx = cv.getContext('2d');
var pctEl = document.getElementById('pct');

var css = getComputedStyle(root);
var PAPER = css.getPropertyValue('--paper').trim();
var LINE = css.getPropertyValue('--line').trim();
var NODE = css.getPropertyValue('--node').trim();
var NODE_HOT = css.getPropertyValue('--node-hot').trim();
var RING = css.getPropertyValue('--ring').trim();

var GX = 9, GY = 6;
var STIFFNESS = 9;                  // 스프링 강성 상수(훅 대상) — spring-mesh-stiffness, 값이 클수록 빨리 흔들린다
var DAMP = 3.4;                     // 감쇠 계수 — 흔들림이 잦아드는 속도
var AMP = 9;                        // 최대 변위(px)
var LOOP = 2.2;

var W = 0, H = 0, dpr = 1, cxp = 0, cyp = 0, maxR = 0, pts = [];

function fit() {
  var r = field.getBoundingClientRect();
  dpr = window.devicePixelRatio || 1;
  W = r.width; H = r.height;
  cv.width = Math.round(W * dpr); cv.height = Math.round(H * dpr);
  ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
  cxp = W * 0.5; cyp = H * 0.5;
  maxR = Math.max(cxp, cyp) * 1.05 + Math.min(W, H) * 0.1;

  var mx = W * 0.1, my = H * 0.14;
  pts = [];
  for (var gy = 0; gy < GY; gy++) {
    for (var gx = 0; gx < GX; gx++) {
      var px = mx + (W - mx * 2) * (gx / (GX - 1));
      var py = my + (H - my * 2) * (gy / (GY - 1));
      var dx = px - cxp, dy = py - cyp;
      var dist = Math.sqrt(dx * dx + dy * dy) || 0.0001;
      pts.push({ px: px, py: py, ux: dx / dist, uy: dy / dist, dist: dist });
    }
  }
}

function ripple(dt) {
  if (dt < 0) return 0;
  return AMP * Math.exp(-DAMP * dt) * Math.cos(STIFFNESS * dt);
}

function draw(sec) {
  var t = sec % LOOP;
  var p = t / LOOP;
  var frontR = p * maxR;
  var speed = maxR / LOOP;

  ctx.fillStyle = PAPER;
  ctx.fillRect(0, 0, W, H);

  ctx.strokeStyle = RING;
  ctx.lineWidth = 1.4;
  ctx.beginPath();
  ctx.arc(cxp, cyp, Math.max(2, frontR), 0, Math.PI * 2);
  ctx.stroke();

  var disp = new Array(pts.length);
  for (var i = 0; i < pts.length; i++) {
    var q = pts[i];
    var dt = (t - q.dist / speed);
    disp[i] = ripple(dt);
  }

  ctx.strokeStyle = LINE;
  ctx.lineWidth = 1.2;
  for (var gy = 0; gy < GY; gy++) {
    for (var gx = 0; gx < GX; gx++) {
      var idx = gy * GX + gx;
      var q2 = pts[idx];
      var x1 = q2.px + q2.ux * disp[idx];
      var y1 = q2.py + q2.uy * disp[idx];
      if (gx < GX - 1) {
        var idxR = idx + 1;
        var qR = pts[idxR];
        var x2 = qR.px + qR.ux * disp[idxR];
        var y2 = qR.py + qR.uy * disp[idxR];
        ctx.beginPath(); ctx.moveTo(x1, y1); ctx.lineTo(x2, y2); ctx.stroke();
      }
      if (gy < GY - 1) {
        var idxD = idx + GX;
        var qD = pts[idxD];
        var x3 = qD.px + qD.ux * disp[idxD];
        var y3 = qD.py + qD.uy * disp[idxD];
        ctx.beginPath(); ctx.moveTo(x1, y1); ctx.lineTo(x3, y3); ctx.stroke();
      }
    }
  }

  for (var k = 0; k < pts.length; k++) {
    var qq = pts[k];
    var x = qq.px + qq.ux * disp[k];
    var y = qq.py + qq.uy * disp[k];
    var heat = Math.min(1, Math.abs(disp[k]) / AMP);
    ctx.fillStyle = heat > 0.18 ? NODE_HOT : NODE;
    ctx.beginPath();
    ctx.arc(x, y, 2.6 + heat * 2.4, 0, Math.PI * 2);
    ctx.fill();
  }

  pctEl.textContent = Math.round(p * 100) + '%';
}

var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
var paused = false;
var t0 = 0;
var raf = 0;

function togglePause() {
  paused = !paused;
  root.classList.toggle('is-paused', paused);
}
function restart() {
  t0 = performance.now();
  draw(0);
}

field.addEventListener('click', function () { togglePause(); });
field.addEventListener('keydown', function (e) {
  if (e.key === ' ' || e.key === 'Enter') { e.preventDefault(); togglePause(); }
  else if (e.key === 'r' || e.key === 'R') { e.preventDefault(); restart(); }
});
window.addEventListener('resize', function () {
  fit();
  if (paused || reduce) draw(((performance.now() - t0) / 1000));
});

function frame(now) {
  if (!paused) draw((now - t0) / 1000);
  raf = requestAnimationFrame(frame);
}

t0 = performance.now();
fit();
if (reduce) {
  root.classList.add('is-still');
  draw(LOOP * 0.62);
} else {
  raf = requestAnimationFrame(frame);
}

// SpringMesh — vanilla 판(run/395/demo/07-canvas-loader-spring-mesh-ripple-radius/index.html) 의 React 포트.
// 파동 반경이 중심에서 번지고, 파동이 닿은 격자점마다 감쇠 스프링(닫힌해 SHM)으로 튕겼다가 가라앉는다.
import { useEffect, useRef } from "react";
import type { CSSProperties } from "react";
import styles from "./SpringMesh.module.scss";

export type SpringMeshProps = {
  duration?: string;
  easing?: string;
  color?: string;
};

type Vars = CSSProperties & { "--duration"?: string; "--easing"?: string; "--color"?: string };
type Box<T> = { current: T };
type KeyEvt = { key: string; preventDefault(): void };
type Pt = { px: number; py: number; ux: number; uy: number; dist: number };

const GX = 9, GY = 6;
const STIFFNESS = 9;   // 스프링 강성 상수(훅 대상) — spring-mesh-stiffness, 값이 클수록 빨리 흔들린다
const DAMP = 3.4;
const AMP = 9;
const LOOP = 2.2;
const FIELD_LABEL = "스프링 격자 파동 실험판";

function ripple(dt: number): number {
  if (dt < 0) return 0;
  return AMP * Math.exp(-DAMP * dt) * Math.cos(STIFFNESS * dt);
}

export default function SpringMesh({
  duration = "2.2s",
  easing = "cubic-bezier(.2, 1.4, .4, 1)",   // vanilla $easing: $ease-pop
  color = "#c93000",                          // vanilla $color: $subject-orange-deep
}: SpringMeshProps) {
  const rootRef = useRef<HTMLDivElement | null>(null);
  const fieldRef = useRef<HTMLDivElement | null>(null);
  const cvRef = useRef<HTMLCanvasElement | null>(null);
  const ctxRef = useRef<CanvasRenderingContext2D | null>(null);
  const pctRef = useRef<HTMLSpanElement | null>(null);
  const sizeRef = useRef({ w: 0, h: 0, dpr: 1, cx: 0, cy: 0, maxR: 0 }) as Box<{ w: number; h: number; dpr: number; cx: number; cy: number; maxR: number }>;
  const ptsRef = useRef<Pt[]>([]) as Box<Pt[]>;
  const pausedRef = useRef(false) as Box<boolean>;
  const t0Ref = useRef(0) as Box<number>;
  const rafRef = useRef(0) as Box<number>;
  const vars: Vars = { "--duration": duration, "--easing": easing, "--color": color };

  function reduced(): boolean {
    return window.matchMedia("(prefers-reduced-motion: reduce)").matches;
  }

  function fit(): void {
    const field = fieldRef.current;
    const cv = cvRef.current;
    const ctx = ctxRef.current;
    if (!field || !cv || !ctx) return;
    const r = field.getBoundingClientRect();
    const dpr = window.devicePixelRatio || 1;
    const size = sizeRef.current;
    size.w = r.width; size.h = r.height; size.dpr = dpr;
    cv.width = Math.round(r.width * dpr);
    cv.height = Math.round(r.height * dpr);
    ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
    size.cx = r.width * 0.5; size.cy = r.height * 0.5;
    size.maxR = Math.max(size.cx, size.cy) * 1.05 + Math.min(r.width, r.height) * 0.1;

    const mx = r.width * 0.1, my = r.height * 0.14;
    const list: Pt[] = [];
    for (let gy = 0; gy < GY; gy++) {
      for (let gx = 0; gx < GX; gx++) {
        const px = mx + (r.width - mx * 2) * (gx / (GX - 1));
        const py = my + (r.height - my * 2) * (gy / (GY - 1));
        const dx = px - size.cx, dy = py - size.cy;
        const dist = Math.sqrt(dx * dx + dy * dy) || 0.0001;
        list.push({ px, py, ux: dx / dist, uy: dy / dist, dist });
      }
    }
    ptsRef.current = list;
  }

  function draw(sec: number): void {
    const ctx = ctxRef.current;
    const root = rootRef.current;
    if (!ctx || !root) return;
    const size = sizeRef.current;
    const W = size.w, H = size.h;
    const t = sec % LOOP;
    const p = t / LOOP;
    const frontR = p * size.maxR;
    const speed = size.maxR / LOOP;
    const pts = ptsRef.current;

    const cssv = (n: string) => getComputedStyle(root).getPropertyValue(n).trim();
    const PAPER = cssv("--paper"), LINE = cssv("--line"), NODE = cssv("--node"), NODE_HOT = cssv("--node-hot"), RING = cssv("--ring");

    ctx.fillStyle = PAPER;
    ctx.fillRect(0, 0, W, H);

    ctx.strokeStyle = RING;
    ctx.lineWidth = 1.4;
    ctx.beginPath();
    ctx.arc(size.cx, size.cy, Math.max(2, frontR), 0, Math.PI * 2);
    ctx.stroke();

    const disp = new Array(pts.length);
    for (let i = 0; i < pts.length; i++) {
      const q = pts[i];
      const dt = t - q.dist / speed;
      disp[i] = ripple(dt);
    }

    ctx.strokeStyle = LINE;
    ctx.lineWidth = 1.2;
    for (let gy = 0; gy < GY; gy++) {
      for (let gx = 0; gx < GX; gx++) {
        const idx = gy * GX + gx;
        const q2 = pts[idx];
        const x1 = q2.px + q2.ux * disp[idx];
        const y1 = q2.py + q2.uy * disp[idx];
        if (gx < GX - 1) {
          const idxR = idx + 1;
          const qR = pts[idxR];
          const x2 = qR.px + qR.ux * disp[idxR];
          const y2 = qR.py + qR.uy * disp[idxR];
          ctx.beginPath(); ctx.moveTo(x1, y1); ctx.lineTo(x2, y2); ctx.stroke();
        }
        if (gy < GY - 1) {
          const idxD = idx + GX;
          const qD = pts[idxD];
          const x3 = qD.px + qD.ux * disp[idxD];
          const y3 = qD.py + qD.uy * disp[idxD];
          ctx.beginPath(); ctx.moveTo(x1, y1); ctx.lineTo(x3, y3); ctx.stroke();
        }
      }
    }

    for (let k = 0; k < pts.length; k++) {
      const qq = pts[k];
      const x = qq.px + qq.ux * disp[k];
      const y = qq.py + qq.uy * disp[k];
      const heat = Math.min(1, Math.abs(disp[k]) / AMP);
      ctx.fillStyle = heat > 0.18 ? NODE_HOT : NODE;
      ctx.beginPath();
      ctx.arc(x, y, 2.6 + heat * 2.4, 0, Math.PI * 2);
      ctx.fill();
    }

    if (pctRef.current) pctRef.current.textContent = Math.round(p * 100) + "%";
  }

  function togglePause(): void {
    pausedRef.current = !pausedRef.current;
    const root = rootRef.current;
    if (root) root.classList.toggle("is-paused", pausedRef.current);
  }

  function restart(): void {
    t0Ref.current = performance.now();
    draw(0);
  }

  function onKey(e: KeyEvt): void {
    if (e.key === " " || e.key === "Enter") { e.preventDefault(); togglePause(); }
    else if (e.key === "r" || e.key === "R") { e.preventDefault(); restart(); }
  }

  function onClick(): void {
    togglePause();
  }

  function onResize(): void {
    fit();
    if (pausedRef.current || reduced()) draw((performance.now() - t0Ref.current) / 1000);
  }

  function frame(now: number): void {
    if (!pausedRef.current) draw((now - t0Ref.current) / 1000);
    rafRef.current = requestAnimationFrame(frame);
  }

  useEffect(() => {
    const cv = cvRef.current;
    if (!cv) return;
    ctxRef.current = cv.getContext("2d");
    if (!ctxRef.current) return;
    t0Ref.current = performance.now();
    fit();
    window.addEventListener("resize", onResize);
    if (reduced()) {
      const root = rootRef.current;
      if (root) root.classList.add("is-still");
      draw(LOOP * 0.62);
    } else {
      rafRef.current = requestAnimationFrame(frame);
    }
    return () => {
      window.removeEventListener("resize", onResize);
      cancelAnimationFrame(rafRef.current);
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div className={styles.root} ref={rootRef} style={vars}>
        <p className={styles.hint}>
          <svg className={styles.ico} viewBox="0 0 256 256" aria-hidden="true"><g fill="currentColor"><path d="M232 56v56a8 8 0 0 1-16 0V91.3l-25.6 25.7A80 80 0 1 1 174 60a8 8 0 1 1-9 13.2A64 64 0 1 0 179.7 128H216a8 8 0 0 1 0 16h-56a8 8 0 0 1-8-8V80a8 8 0 0 1 16 0v20.7L192.7 76A80.1 80.1 0 0 0 64 128a8 8 0 0 1-16 0a96 96 0 0 1 163.6-68.3L224 71.3V56a8 8 0 0 1 8 8" opacity=".2"/><path d="M224 48a8 8 0 0 0-8 8v15.3l-11.7-11.6a96 96 0 1 0 27.6 51.6a8 8 0 0 0-15.8 2.5a80 80 0 1 1-23-43l-25.7 25.7A8 8 0 0 0 173 112h56a8 8 0 0 0 8-8V56a8 8 0 0 0-13-8"/></g></svg>
          <span>클릭하거나 스페이스바를 누르면 멈추거나 다시 갑니다</span>
        </p>
        <div
          className={styles.field}
          ref={fieldRef}
          role="application"
          aria-label={FIELD_LABEL}
          tabIndex={0}
          onClick={onClick}
          onKeyDown={onKey}
        >
          <canvas className={styles.cv} ref={cvRef}></canvas>
          <b className={styles.badge} aria-hidden="true"><span className={styles.badgeNum} ref={pctRef}>0%</span><span className={styles.badgeUnit}>파동</span></b>
        </div>
      </div>
    </main>
  );
}