01가장자리만 배경을 휘게 하는 굴절 렌즈

<main class="stage">
<div class="lg is-demo" id="lgRoot" tabindex="0">
  <canvas class="lg__canvas" id="lgCanvas" width="480" height="300"></canvas>
  <p class="lg__caption">판 안쪽은 배경이 그대로 보이고, 가장자리 두께만큼 배경 화면이 안쪽으로 휘어 보인다</p>
</div>
</main>

@use "../../../../site/static/demo-tokens" as *;
@include stage($stage-ink);

.lg {
  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;
  outline: none;
}

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

.lg__caption {
  position: absolute;
  left: $sp-3;
  bottom: $sp-3;
  max-width: 78%;
  margin: 0;
  padding: $sp-1 $sp-3;
  border-radius: $r-pill;
  background: rgba(23, 20, 26, .68);
  color: $stage-paper;
  font-weight: 500;
  font-size: 12px;
  line-height: 1.4;
  pointer-events: none;
}

@media (max-width: 340px) {
  .lg__caption { font-size: 10px; padding: $sp-1 $sp-2; }
}

@media (prefers-reduced-motion: reduce) {
  .lg { 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);
}

.lg {
  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);
  outline: none;
}

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

.lg__caption {
  position: absolute;
  left: 12px;
  bottom: 12px;
  max-width: 78%;
  margin: 0;
  padding: 4px 12px;
  border-radius: 999px;
  background: rgba(23, 20, 26, 0.68);
  color: #ffffff;
  font-weight: 500;
  font-size: 12px;
  line-height: 1.4;
  pointer-events: none;
}

@media (max-width: 340px) {
  .lg__caption {
    font-size: 10px;
    padding: 4px 8px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .lg {
    cursor: default;
  }
}

(function () {
  // 기법: 유리 판 사각형의 가장자리 거리(사각 SDF 근사)를 재고, 그 거리로 만든 법선 방향을
  // 따라 배경 샘플 좌표를 안쪽으로 밀어(굴절 오프셋) putImageData 로 그린다. 판 중심은 배경 그대로.
  var root = document.getElementById('lgRoot');
  var canvas = document.getElementById('lgCanvas');
  var ctx = canvas.getContext('2d');
  var wrap = canvas.parentElement;

  function seedRand(seed) {
    var s = seed >>> 0;
    return function () { s = (s * 1664525 + 1013904223) >>> 0; return s / 4294967296; };
  }

  var CALC_W = 160, CALC_H = 100;
  var SCENE_W = 260;
  var scene = document.createElement('canvas');
  scene.width = SCENE_W; scene.height = CALC_H;
  (function drawScene() {
    var pctx = scene.getContext('2d');
    var rand = seedRand(421011);
    var sky = pctx.createLinearGradient(0, 0, 0, CALC_H);
    sky.addColorStop(0, '#dfe8ff');
    sky.addColorStop(1, '#f7f0ff');
    pctx.fillStyle = sky;
    pctx.fillRect(0, 0, SCENE_W, CALC_H);
    var glow = pctx.createRadialGradient(SCENE_W * 0.3, CALC_H * 0.2, 0, SCENE_W * 0.3, CALC_H * 0.2, CALC_H * 0.9);
    glow.addColorStop(0, 'rgba(255,255,255,.6)');
    glow.addColorStop(1, 'rgba(255,255,255,0)');
    pctx.fillStyle = glow;
    pctx.fillRect(0, 0, SCENE_W, CALC_H);
    var bands = ['#b9a0ff', '#6ec8ff', '#4cd4a6'];
    for (var i = 0; i < bands.length; i += 1) {
      var baseY = CALC_H * (0.42 + i * 0.17);
      pctx.beginPath();
      pctx.moveTo(0, CALC_H);
      var step = 6;
      for (var x = 0; x <= SCENE_W; x += step) {
        var n = Math.sin(x * 0.05 + i * 2.1) * CALC_H * 0.05;
        pctx.lineTo(x, baseY + n);
      }
      pctx.lineTo(SCENE_W, CALC_H);
      pctx.closePath();
      pctx.fillStyle = bands[i];
      pctx.fill();
    }
    for (var k = 0; k < 60; k += 1) {
      var px = rand() * SCENE_W, py = rand() * CALC_H, r = rand() * 1.1 + 0.4;
      pctx.beginPath();
      pctx.arc(px, py, r, 0, Math.PI * 2);
      pctx.fillStyle = 'rgba(255,255,255,' + (0.1 + rand() * 0.2) + ')';
      pctx.fill();
    }
  }());
  var sceneCtx = scene.getContext('2d');
  var sceneImg = sceneCtx.getImageData(0, 0, SCENE_W, CALC_H);
  var sceneBuf = sceneImg.data;

  function sampleScene(sx, sy) {
    sx = sx < 0 ? 0 : (sx > SCENE_W - 1 ? SCENE_W - 1 : sx);
    sy = sy < 0 ? 0 : (sy > CALC_H - 1 ? CALC_H - 1 : sy);
    var i = (Math.round(sy) * SCENE_W + Math.round(sx)) * 4;
    return [sceneBuf[i], sceneBuf[i + 1], sceneBuf[i + 2]];
  }

  var PANEL_X0 = 20, PANEL_Y0 = 16, PANEL_X1 = 140, PANEL_Y1 = 84;
  var EDGE_BAND = 16;
  var GLASS_REFRACTION_STRENGTH = 8;
  var SCENE_OFFSET_X = (SCENE_W - CALC_W) / 2;
  var PAN_AMP = 34;
  var PERIOD_MS = 2000;

  function boxEdgeSample(x, y, x0, y0, x1, y1, band) {
    var dl = x - x0, dr = x1 - x, dt = y - y0, db = y1 - y;
    var dmin = Math.min(dl, dr, dt, db);
    if (dmin >= band || dmin < 0) return { f: 0, nx: 0, ny: 0 };
    var nx = 0, ny = 0;
    if (dl < band) nx -= (band - dl);
    if (dr < band) nx += (band - dr);
    if (dt < band) ny -= (band - dt);
    if (db < band) ny += (band - db);
    var len = Math.sqrt(nx * nx + ny * ny);
    if (len > 0.0001) { nx /= len; ny /= len; }
    return { f: Math.max(0, (band - dmin) / band), nx: nx, ny: ny };
  }

  function panX(t) {
    return PAN_AMP * Math.sin(t * 2 * Math.PI / PERIOD_MS);
  }

  var out = document.createElement('canvas');
  out.width = CALC_W; out.height = CALC_H;
  var outCtx = out.getContext('2d');
  var outImg = outCtx.createImageData(CALC_W, CALC_H);
  var outBuf = outImg.data;

  function renderFrame(t) {
    var pan = panX(t);
    var idx = 0;
    for (var y = 0; y < CALC_H; y += 1) {
      for (var x = 0; x < CALC_W; x += 1) {
        var baseSx = x + SCENE_OFFSET_X + pan;
        var rgb;
        if (x >= PANEL_X0 && x <= PANEL_X1 && y >= PANEL_Y0 && y <= PANEL_Y1) {
          var e = boxEdgeSample(x, y, PANEL_X0, PANEL_Y0, PANEL_X1, PANEL_Y1, EDGE_BAND);
          var ripple = Math.sin((x + y) * 0.12 - t * 0.006) * 0.25 * e.f;
          var mag = (e.f + ripple) * GLASS_REFRACTION_STRENGTH;
          rgb = sampleScene(baseSx - e.nx * mag, y - e.ny * mag);
          var shine = e.f * 26 - Math.max(0, ripple) * 10;
          rgb = [Math.min(255, rgb[0] + shine), Math.min(255, rgb[1] + shine), Math.min(255, rgb[2] + shine)];
        } else {
          rgb = sampleScene(baseSx, y);
        }
        outBuf[idx] = rgb[0]; outBuf[idx + 1] = rgb[1]; outBuf[idx + 2] = rgb[2]; outBuf[idx + 3] = 255;
        idx += 4;
      }
    }
  }

  var cw = 480, ch = 300;
  function fit() {
    var r = wrap.getBoundingClientRect();
    cw = Math.max(1, Math.round(r.width));
    ch = Math.max(1, Math.round(r.height));
    canvas.width = cw; canvas.height = ch;
    draw(lastElapsed);
  }

  var lastElapsed = 0;
  function draw(t) {
    lastElapsed = t;
    renderFrame(t);
    outCtx.putImageData(outImg, 0, 0);
    ctx.clearRect(0, 0, cw, ch);
    ctx.drawImage(out, 0, 0, CALC_W, CALC_H, 0, 0, cw, ch);
  }

  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  if (reduce) { root.classList.remove('is-demo'); }

  var lastTs = null;
  var elapsed = 0;
  function tick(ts) {
    if (lastTs === null) lastTs = ts;
    var dt = ts - lastTs;
    lastTs = ts;
    elapsed += dt;
    draw(elapsed);
    requestAnimationFrame(tick);
  }
  fit();
  window.addEventListener('resize', fit);
  draw(elapsed);
  if (!reduce) requestAnimationFrame(tick);
})();

// EdgeRefractionLens — vanilla 판(run/421/demo/01-liquid-glass-edge-refraction-lens/index.html) 의 React 포트.
// 유리 판 사각형의 가장자리 거리(사각 SDF 근사)를 재고, 그 거리로 만든 법선 방향을
// 따라 배경 샘플 좌표를 안쪽으로 밀어(굴절 오프셋) putImageData 로 그린다. 판 중심은 배경 그대로.
import { useEffect, useRef } from "react";
import styles from "./EdgeRefractionLens.module.scss";

type Box<T> = { current: T };
type Edge = { f: number; nx: number; ny: number };

const CALC_W = 160, CALC_H = 100;
const SCENE_W = 260;
const PANEL_X0 = 20, PANEL_Y0 = 16, PANEL_X1 = 140, PANEL_Y1 = 84;
const EDGE_BAND = 16;
const GLASS_REFRACTION_STRENGTH = 8;
const SCENE_OFFSET_X = (SCENE_W - CALC_W) / 2;
const PAN_AMP = 34;
const PERIOD_MS = 2000;

interface State {
  ctx: CanvasRenderingContext2D | null;
  wrap: HTMLElement | null;
  sceneBuf: Uint8ClampedArray | null;
  outCtx: CanvasRenderingContext2D | null;
  out: HTMLCanvasElement | null;
  outImg: ImageData | null;
  outBuf: Uint8ClampedArray | null;
  cw: number; ch: number;
  lastElapsed: number;
  lastTs: number | null;
  elapsed: number;
  raf: number;
  reduce: boolean;
}

function seedRand(seed: number): () => number {
  let s = seed >>> 0;
  return function () { s = (s * 1664525 + 1013904223) >>> 0; return s / 4294967296; };
}

function boxEdgeSample(x: number, y: number, x0: number, y0: number, x1: number, y1: number, band: number): Edge {
  const dl = x - x0, dr = x1 - x, dt = y - y0, db = y1 - y;
  const dmin = Math.min(dl, dr, dt, db);
  if (dmin >= band || dmin < 0) return { f: 0, nx: 0, ny: 0 };
  let nx = 0, ny = 0;
  if (dl < band) nx -= (band - dl);
  if (dr < band) nx += (band - dr);
  if (dt < band) ny -= (band - dt);
  if (db < band) ny += (band - db);
  const len = Math.sqrt(nx * nx + ny * ny);
  if (len > 0.0001) { nx /= len; ny /= len; }
  return { f: Math.max(0, (band - dmin) / band), nx, ny };
}

function panX(t: number): number {
  return PAN_AMP * Math.sin((t * 2 * Math.PI) / PERIOD_MS);
}

export default function EdgeRefractionLens() {
  const rootRef = useRef<HTMLDivElement | null>(null);
  const canvasRef = useRef<HTMLCanvasElement | null>(null);
  const st = useRef({
    ctx: null, wrap: null, sceneBuf: null, outCtx: null, out: null, outImg: null, outBuf: null,
    cw: 480, ch: 300, lastElapsed: 0, lastTs: null, elapsed: 0, raf: 0, reduce: false,
  }) as Box<State>;

  function sampleScene(sx: number, sy: number): number[] {
    const buf = st.current.sceneBuf!;
    const cx = sx < 0 ? 0 : sx > SCENE_W - 1 ? SCENE_W - 1 : sx;
    const cy = sy < 0 ? 0 : sy > CALC_H - 1 ? CALC_H - 1 : sy;
    const i = (Math.round(cy) * SCENE_W + Math.round(cx)) * 4;
    return [buf[i], buf[i + 1], buf[i + 2]];
  }

  function renderFrame(t: number): void {
    const outBuf = st.current.outBuf!;
    const pan = panX(t);
    let idx = 0;
    for (let y = 0; y < CALC_H; y += 1) {
      for (let x = 0; x < CALC_W; x += 1) {
        const baseSx = x + SCENE_OFFSET_X + pan;
        let rgb: number[];
        if (x >= PANEL_X0 && x <= PANEL_X1 && y >= PANEL_Y0 && y <= PANEL_Y1) {
          const e = boxEdgeSample(x, y, PANEL_X0, PANEL_Y0, PANEL_X1, PANEL_Y1, EDGE_BAND);
          const ripple = Math.sin((x + y) * 0.12 - t * 0.006) * 0.25 * e.f;
          const mag = (e.f + ripple) * GLASS_REFRACTION_STRENGTH;
          rgb = sampleScene(baseSx - e.nx * mag, y - e.ny * mag);
          const shine = e.f * 26 - Math.max(0, ripple) * 10;
          rgb = [Math.min(255, rgb[0] + shine), Math.min(255, rgb[1] + shine), Math.min(255, rgb[2] + shine)];
        } else {
          rgb = sampleScene(baseSx, y);
        }
        outBuf[idx] = rgb[0]; outBuf[idx + 1] = rgb[1]; outBuf[idx + 2] = rgb[2]; outBuf[idx + 3] = 255;
        idx += 4;
      }
    }
  }

  function draw(t: number): void {
    const s = st.current;
    s.lastElapsed = t;
    renderFrame(t);
    s.outCtx!.putImageData(s.outImg!, 0, 0);
    s.ctx!.clearRect(0, 0, s.cw, s.ch);
    s.ctx!.drawImage(s.out!, 0, 0, CALC_W, CALC_H, 0, 0, s.cw, s.ch);
  }

  function fit(): void {
    const s = st.current;
    const canvas = canvasRef.current;
    if (!s.wrap || !canvas) return;
    const r = s.wrap.getBoundingClientRect();
    s.cw = Math.max(1, Math.round(r.width));
    s.ch = Math.max(1, Math.round(r.height));
    canvas.width = s.cw; canvas.height = s.ch;
    draw(s.lastElapsed);
  }

  function tick(ts: number): void {
    const s = st.current;
    if (s.lastTs === null) s.lastTs = ts;
    const dt = ts - s.lastTs;
    s.lastTs = ts;
    s.elapsed += dt;
    draw(s.elapsed);
    s.raf = requestAnimationFrame(tick);
  }

  useEffect(() => {
    const root = rootRef.current;
    const canvas = canvasRef.current;
    if (!root || !canvas) return;
    const ctx = canvas.getContext("2d");
    const wrap = canvas.parentElement;
    if (!ctx || !wrap) return;

    const scene = document.createElement("canvas");
    scene.width = SCENE_W; scene.height = CALC_H;
    const pctx = scene.getContext("2d")!;
    const rand = seedRand(421011);
    const sky = pctx.createLinearGradient(0, 0, 0, CALC_H);
    sky.addColorStop(0, "#dfe8ff");
    sky.addColorStop(1, "#f7f0ff");
    pctx.fillStyle = sky;
    pctx.fillRect(0, 0, SCENE_W, CALC_H);
    const glow = pctx.createRadialGradient(SCENE_W * 0.3, CALC_H * 0.2, 0, SCENE_W * 0.3, CALC_H * 0.2, CALC_H * 0.9);
    glow.addColorStop(0, "rgba(255,255,255,.6)");
    glow.addColorStop(1, "rgba(255,255,255,0)");
    pctx.fillStyle = glow;
    pctx.fillRect(0, 0, SCENE_W, CALC_H);
    const bands = ["#b9a0ff", "#6ec8ff", "#4cd4a6"];
    for (let i = 0; i < bands.length; i += 1) {
      const baseY = CALC_H * (0.42 + i * 0.17);
      pctx.beginPath();
      pctx.moveTo(0, CALC_H);
      const step = 6;
      for (let x = 0; x <= SCENE_W; x += step) {
        const n = Math.sin(x * 0.05 + i * 2.1) * CALC_H * 0.05;
        pctx.lineTo(x, baseY + n);
      }
      pctx.lineTo(SCENE_W, CALC_H);
      pctx.closePath();
      pctx.fillStyle = bands[i];
      pctx.fill();
    }
    for (let k = 0; k < 60; k += 1) {
      const px = rand() * SCENE_W, py = rand() * CALC_H, r = rand() * 1.1 + 0.4;
      pctx.beginPath();
      pctx.arc(px, py, r, 0, Math.PI * 2);
      pctx.fillStyle = "rgba(255,255,255," + (0.1 + rand() * 0.2) + ")";
      pctx.fill();
    }
    const sceneImg = pctx.getImageData(0, 0, SCENE_W, CALC_H);

    const out = document.createElement("canvas");
    out.width = CALC_W; out.height = CALC_H;
    const outCtx = out.getContext("2d")!;
    const outImg = outCtx.createImageData(CALC_W, CALC_H);

    const s = st.current;
    s.ctx = ctx; s.wrap = wrap; s.sceneBuf = sceneImg.data;
    s.outCtx = outCtx; s.out = out; s.outImg = outImg; s.outBuf = outImg.data;
    s.reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    if (s.reduce) { root.classList.remove("is-demo"); }

    fit();
    window.addEventListener("resize", fit);
    draw(s.elapsed);
    if (!s.reduce) s.raf = requestAnimationFrame(tick);

    return () => {
      window.removeEventListener("resize", fit);
      cancelAnimationFrame(st.current.raf);
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div className={`${styles.lg} is-demo`} ref={rootRef} tabIndex={0}>
        <canvas className={styles.lg__canvas} ref={canvasRef} width={480} height={300} />
        <p className={styles.lg__caption}>판 안쪽은 배경이 그대로 보이고, 가장자리 두께만큼 배경 화면이 안쪽으로 휘어 보인다</p>
      </div>
    </main>
  );
}