07Ripple That Grows With Sound Level

<main class="stage">
<div class="rv is-demo" id="rvRoot">
  <canvas class="rv__canvas" id="rvCanvas" width="480" height="300"></canvas>
  <p class="rv__caption">Each time the synthesized audio level rises, ripples strike the image's surface harder.</p>
  <div class="rv__control">
    <label class="rv__label" for="rvGain">Response strength</label>
    <input class="rv__range" id="rvGain" type="range" min="10" max="160" value="40" step="1" aria-label="Response strength">
  </div>
</div>
</main>

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

.rv {
  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;
}

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

.rv__caption {
  position: absolute;
  left: $sp-3;
  top: $sp-3;
  max-width: 70%;
  margin: 0;
  padding: $sp-1 $sp-3;
  border-radius: $r-pill;
  background: rgba(255, 247, 230, .85);
  color: $subject-ink;
  font-weight: 500;
  font-size: 12px;
  line-height: 1.4;
  pointer-events: none;
}

.rv__control {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  display: flex;
  align-items: center;
  gap: $sp-2;
  box-sizing: border-box;
  padding: $sp-2 $sp-3;
  background: rgba(23, 20, 26, .55);
}

.rv__label {
  flex: 0 0 auto;
  font-size: 11px;
  font-weight: 600;
  color: $stage-paper;
  white-space: nowrap;
}

.rv__range {
  flex: 1 1 auto;
  min-width: 0;
  width: 0;
  accent-color: $subject-blue;
}

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

@media (prefers-reduced-motion: reduce) {
  .rv { cursor: default; }
}

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);
}

.rv {
  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);
}

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

.rv__caption {
  position: absolute;
  left: 12px;
  top: 12px;
  max-width: 70%;
  margin: 0;
  padding: 4px 12px;
  border-radius: 999px;
  background: rgba(255, 247, 230, 0.85);
  color: #17141a;
  font-weight: 500;
  font-size: 12px;
  line-height: 1.4;
  pointer-events: none;
}

.rv__control {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  display: flex;
  align-items: center;
  gap: 8px;
  box-sizing: border-box;
  padding: 8px 12px;
  background: rgba(23, 20, 26, 0.55);
}

.rv__label {
  flex: 0 0 auto;
  font-size: 11px;
  font-weight: 600;
  color: #ffffff;
  white-space: nowrap;
}

.rv__range {
  flex: 1 1 auto;
  min-width: 0;
  width: 0;
  accent-color: #2f6df6;
}

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

(function () {
  // 기법: 실제 마이크·파일 없이 시간 함수로 합성한 가상 오디오 레벨 곡선(virtualAudioLevel)을 만든다.
  // 레벨이 문턱을 넘을 때마다 높이 필드 2버퍼 파동식에 임펄스를 찍어 RIPPLE_AUDIO_GAIN 배율로 세기를 조절한다.
  var root = document.getElementById('rvRoot');
  var canvas = document.getElementById('rvCanvas');
  var ctx = canvas.getContext('2d');
  var wrap = canvas.parentElement;
  var gainInput = document.getElementById('rvGain');

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

  function drawPhotoBase(pctx, w, h, seed) {
    var rand = seedRand(seed);
    var sky = pctx.createLinearGradient(0, 0, 0, h);
    sky.addColorStop(0, '#2a1640');
    sky.addColorStop(1, '#5c2a6b');
    pctx.fillStyle = sky;
    pctx.fillRect(0, 0, w, h);
    var sunX = w * 0.62, sunY = h * 0.24, sunR = h * 0.14;
    var glow = pctx.createRadialGradient(sunX, sunY, 0, sunX, sunY, sunR * 2.8);
    glow.addColorStop(0, 'rgba(255,140,200,.75)');
    glow.addColorStop(1, 'rgba(255,140,200,0)');
    pctx.fillStyle = glow;
    pctx.fillRect(0, 0, w, h);
    pctx.beginPath();
    pctx.arc(sunX, sunY, sunR, 0, Math.PI * 2);
    pctx.fillStyle = '#ffd6f2';
    pctx.fill();
    var hillColors = ['#7a3b8a', '#4a2364', '#251140'];
    for (var i = 0; i < hillColors.length; i += 1) {
      var baseY = h * (0.5 + i * 0.14);
      pctx.beginPath();
      pctx.moveTo(0, h);
      var step = Math.max(2, w / 24);
      for (var x = 0; x <= w; x += step) {
        var n = Math.sin(x * 0.06 + i * 2 + seed * 0.0003) * h * 0.04;
        pctx.lineTo(x, baseY + n);
      }
      pctx.lineTo(w, h);
      pctx.closePath();
      pctx.fillStyle = hillColors[i];
      pctx.fill();
    }
    for (var k = 0; k < 60; k += 1) {
      var px = rand() * w, py = rand() * h * 0.6, r = rand() * 1.2 + 0.3;
      pctx.beginPath();
      pctx.arc(px, py, r, 0, Math.PI * 2);
      pctx.fillStyle = 'rgba(255,255,255,' + (0.12 + rand() * 0.22) + ')';
      pctx.fill();
    }
  }

  var CALC_W = 160, CALC_H = 100;
  var RIPPLE_AUDIO_GAIN = 0.4;

  var gridA = new Float32Array(CALC_W * CALC_H);
  var gridB = new Float32Array(CALC_W * CALC_H);
  var damping = 0.965;

  function cellIndex(x, y) { return y * CALC_W + x; }

  function splashAt(gx, gy, amp) {
    gx = Math.round(gx); gy = Math.round(gy);
    for (var dy = -1; dy <= 1; dy += 1) {
      for (var dx = -1; dx <= 1; dx += 1) {
        var x = gx + dx, y = gy + dy;
        if (x > 0 && x < CALC_W - 1 && y > 0 && y < CALC_H - 1) {
          gridA[cellIndex(x, y)] += amp * (dx === 0 && dy === 0 ? 1 : 0.4);
        }
      }
    }
  }

  function stepWave() {
    for (var y = 1; y < CALC_H - 1; y += 1) {
      var row = y * CALC_W;
      for (var x = 1; x < CALC_W - 1; x += 1) {
        var i = row + x;
        var next = (gridA[i - 1] + gridA[i + 1] + gridA[i - CALC_W] + gridA[i + CALC_W]) / 2 - gridB[i];
        gridB[i] = next * damping;
      }
    }
    var t = gridA; gridA = gridB; gridB = t;
  }

  var off = document.createElement('canvas');
  off.width = CALC_W; off.height = CALC_H;
  var octx = off.getContext('2d');
  drawPhotoBase(octx, CALC_W, CALC_H, 419071);
  var baseImg = octx.getImageData(0, 0, CALC_W, CALC_H);
  var baseBuf = baseImg.data;

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

  function renderField() {
    var idx = 0;
    for (var y = 0; y < CALC_H; y += 1) {
      var row = y * CALC_W;
      for (var x = 0; x < CALC_W; x += 1) {
        var i = row + x;
        var hl = x > 0 ? gridA[i - 1] : gridA[i];
        var hr = x < CALC_W - 1 ? gridA[i + 1] : gridA[i];
        var hu = y > 0 ? gridA[i - CALC_W] : gridA[i];
        var hd = y < CALC_H - 1 ? gridA[i + CALC_W] : gridA[i];
        var dx = (hr - hl) * 0.8;
        var dy = (hd - hu) * 0.8;
        var rgb = sampleBase(x + dx, y + dy);
        var shine = Math.max(-30, Math.min(60, (hu - hd) * 0.5));
        outBuf[idx] = Math.max(0, Math.min(255, rgb[0] + shine));
        outBuf[idx + 1] = Math.max(0, Math.min(255, rgb[1] + shine));
        outBuf[idx + 2] = Math.max(0, Math.min(255, rgb[2] + shine));
        outBuf[idx + 3] = 255;
        idx += 4;
      }
    }
  }

  function virtualAudioLevel(t) {
    var beat = Math.pow(Math.abs(Math.sin(t * 0.0026)), 3);
    var pulse = Math.pow(Math.abs(Math.sin(t * 0.00071 + 1.3)), 5);
    var flicker = 0.5 + 0.5 * Math.sin(t * 0.021);
    var level = beat * 0.6 + pulse * 0.5 + flicker * 0.15;
    return Math.max(0, Math.min(1, level));
  }

  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();
  }

  function draw() {
    renderField();
    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;
  var playing = !reduce;
  if (reduce) { root.classList.remove('is-demo'); }

  var gainMul = parseFloat(gainInput.value);
  gainInput.addEventListener('input', function () {
    gainMul = parseFloat(gainInput.value);
    if (reduce) { splashAt(CALC_W * 0.5, CALC_H * 0.5, RIPPLE_AUDIO_GAIN * gainMul * 6); draw(); }
  });

  var lastBeatIdx = -1;
  var BEAT_INTERVAL_MS = 220;
  var lastTs = null;
  var elapsed = 0;
  function tick(ts) {
    if (lastTs === null) lastTs = ts;
    var dt = ts - lastTs;
    lastTs = ts;
    if (playing) {
      elapsed += dt;
      var beatIdx = Math.floor(elapsed / BEAT_INTERVAL_MS);
      if (beatIdx !== lastBeatIdx) {
        lastBeatIdx = beatIdx;
        var level = virtualAudioLevel(elapsed);
        if (level > 0.25) {
          var gx = CALC_W * (0.3 + 0.4 * ((Math.sin(elapsed * 0.0017) + 1) / 2));
          var gy = CALC_H * (0.3 + 0.4 * ((Math.cos(elapsed * 0.0013) + 1) / 2));
          splashAt(gx, gy, -level * RIPPLE_AUDIO_GAIN * gainMul * 10);
        }
      }
      stepWave();
      draw();
    }
    requestAnimationFrame(tick);
  }
  fit();
  window.addEventListener('resize', fit);
  splashAt(CALC_W * 0.5, CALC_H * 0.5, -RIPPLE_AUDIO_GAIN * gainMul * 6);
  draw();
  requestAnimationFrame(tick);
})();

import { useEffect, useRef } from "react";
import styles from "./RippleCanvasAudioReactive.module.scss";

export default function RippleCanvasAudioReactive() {
  const rootRef = useRef<HTMLDivElement>(null);
  const canvasRef = useRef<HTMLCanvasElement>(null);
  const gainRef = useRef<HTMLInputElement>(null);

  useEffect(() => {
    const root = rootRef.current;
    const canvas = canvasRef.current;
    const gainInput = gainRef.current;
    if (!root || !canvas || !gainInput) return;
    const ctx = canvas.getContext("2d") as CanvasRenderingContext2D;
    const wrap = canvas.parentElement as HTMLElement;

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

    function drawPhotoBase(pctx: CanvasRenderingContext2D, w: number, h: number, seed: number) {
      const rand = seedRand(seed);
      const sky = pctx.createLinearGradient(0, 0, 0, h);
      sky.addColorStop(0, "#2a1640");
      sky.addColorStop(1, "#5c2a6b");
      pctx.fillStyle = sky;
      pctx.fillRect(0, 0, w, h);
      const sunX = w * 0.62, sunY = h * 0.24, sunR = h * 0.14;
      const glow = pctx.createRadialGradient(sunX, sunY, 0, sunX, sunY, sunR * 2.8);
      glow.addColorStop(0, "rgba(255,140,200,.75)");
      glow.addColorStop(1, "rgba(255,140,200,0)");
      pctx.fillStyle = glow;
      pctx.fillRect(0, 0, w, h);
      pctx.beginPath();
      pctx.arc(sunX, sunY, sunR, 0, Math.PI * 2);
      pctx.fillStyle = "#ffd6f2";
      pctx.fill();
      const hillColors = ["#7a3b8a", "#4a2364", "#251140"];
      for (let i = 0; i < hillColors.length; i += 1) {
        const baseY = h * (0.5 + i * 0.14);
        pctx.beginPath();
        pctx.moveTo(0, h);
        const step = Math.max(2, w / 24);
        for (let x = 0; x <= w; x += step) {
          const n = Math.sin(x * 0.06 + i * 2 + seed * 0.0003) * h * 0.04;
          pctx.lineTo(x, baseY + n);
        }
        pctx.lineTo(w, h);
        pctx.closePath();
        pctx.fillStyle = hillColors[i];
        pctx.fill();
      }
      for (let k = 0; k < 60; k += 1) {
        const px = rand() * w, py = rand() * h * 0.6, r = rand() * 1.2 + 0.3;
        pctx.beginPath();
        pctx.arc(px, py, r, 0, Math.PI * 2);
        pctx.fillStyle = "rgba(255,255,255," + (0.12 + rand() * 0.22) + ")";
        pctx.fill();
      }
    }

    const CALC_W = 160, CALC_H = 100;
    const RIPPLE_AUDIO_GAIN = 0.4;

    let gridA = new Float32Array(CALC_W * CALC_H);
    let gridB = new Float32Array(CALC_W * CALC_H);
    const damping = 0.965;

    function cellIndex(x: number, y: number) { return y * CALC_W + x; }

    function splashAt(gx: number, gy: number, amp: number) {
      gx = Math.round(gx); gy = Math.round(gy);
      for (let dy = -1; dy <= 1; dy += 1) {
        for (let dx = -1; dx <= 1; dx += 1) {
          const x = gx + dx, y = gy + dy;
          if (x > 0 && x < CALC_W - 1 && y > 0 && y < CALC_H - 1) {
            gridA[cellIndex(x, y)] += amp * (dx === 0 && dy === 0 ? 1 : 0.4);
          }
        }
      }
    }

    function stepWave() {
      for (let y = 1; y < CALC_H - 1; y += 1) {
        const row = y * CALC_W;
        for (let x = 1; x < CALC_W - 1; x += 1) {
          const i = row + x;
          const next = (gridA[i - 1] + gridA[i + 1] + gridA[i - CALC_W] + gridA[i + CALC_W]) / 2 - gridB[i];
          gridB[i] = next * damping;
        }
      }
      const t = gridA; gridA = gridB; gridB = t;
    }

    const off = document.createElement("canvas");
    off.width = CALC_W; off.height = CALC_H;
    const octx = off.getContext("2d") as CanvasRenderingContext2D;
    drawPhotoBase(octx, CALC_W, CALC_H, 419071);
    const baseBuf = octx.getImageData(0, 0, CALC_W, CALC_H).data;

    const out = document.createElement("canvas");
    out.width = CALC_W; out.height = CALC_H;
    const outCtx = out.getContext("2d") as CanvasRenderingContext2D;
    const outImg = outCtx.createImageData(CALC_W, CALC_H);
    const outBuf = outImg.data;

    function sampleBase(sx: number, sy: number): [number, number, number] {
      sx = sx < 0 ? 0 : (sx > CALC_W - 1 ? CALC_W - 1 : sx);
      sy = sy < 0 ? 0 : (sy > CALC_H - 1 ? CALC_H - 1 : sy);
      const i = (Math.round(sy) * CALC_W + Math.round(sx)) * 4;
      return [baseBuf[i], baseBuf[i + 1], baseBuf[i + 2]];
    }

    function renderField() {
      let idx = 0;
      for (let y = 0; y < CALC_H; y += 1) {
        const row = y * CALC_W;
        for (let x = 0; x < CALC_W; x += 1) {
          const i = row + x;
          const hl = x > 0 ? gridA[i - 1] : gridA[i];
          const hr = x < CALC_W - 1 ? gridA[i + 1] : gridA[i];
          const hu = y > 0 ? gridA[i - CALC_W] : gridA[i];
          const hd = y < CALC_H - 1 ? gridA[i + CALC_W] : gridA[i];
          const dx = (hr - hl) * 0.8;
          const dy = (hd - hu) * 0.8;
          const rgb = sampleBase(x + dx, y + dy);
          const shine = Math.max(-30, Math.min(60, (hu - hd) * 0.5));
          outBuf[idx] = Math.max(0, Math.min(255, rgb[0] + shine));
          outBuf[idx + 1] = Math.max(0, Math.min(255, rgb[1] + shine));
          outBuf[idx + 2] = Math.max(0, Math.min(255, rgb[2] + shine));
          outBuf[idx + 3] = 255;
          idx += 4;
        }
      }
    }

    function virtualAudioLevel(t: number) {
      const beat = Math.pow(Math.abs(Math.sin(t * 0.0026)), 3);
      const pulse = Math.pow(Math.abs(Math.sin(t * 0.00071 + 1.3)), 5);
      const flicker = 0.5 + 0.5 * Math.sin(t * 0.021);
      const level = beat * 0.6 + pulse * 0.5 + flicker * 0.15;
      return Math.max(0, Math.min(1, level));
    }

    let cw = 480, ch = 300;
    function draw() {
      renderField();
      outCtx.putImageData(outImg, 0, 0);
      ctx.clearRect(0, 0, cw, ch);
      ctx.drawImage(out, 0, 0, CALC_W, CALC_H, 0, 0, cw, ch);
    }

    function fit() {
      const 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();
    }

    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    const playing = !reduce;
    if (reduce) { root.classList.remove("is-demo"); }

    let gainMul = parseFloat(gainInput.value);
    function onGainInput() {
      gainMul = parseFloat(gainInput!.value);
      if (reduce) { splashAt(CALC_W * 0.5, CALC_H * 0.5, RIPPLE_AUDIO_GAIN * gainMul * 6); draw(); }
    }
    gainInput.addEventListener("input", onGainInput);

    let lastBeatIdx = -1;
    const BEAT_INTERVAL_MS = 220;
    let lastTs: number | null = null;
    let elapsed = 0;
    let raf = 0;
    function tick(ts: number) {
      if (lastTs === null) lastTs = ts;
      const dt = ts - lastTs;
      lastTs = ts;
      if (playing) {
        elapsed += dt;
        const beatIdx = Math.floor(elapsed / BEAT_INTERVAL_MS);
        if (beatIdx !== lastBeatIdx) {
          lastBeatIdx = beatIdx;
          const level = virtualAudioLevel(elapsed);
          if (level > 0.25) {
            const gx = CALC_W * (0.3 + 0.4 * ((Math.sin(elapsed * 0.0017) + 1) / 2));
            const gy = CALC_H * (0.3 + 0.4 * ((Math.cos(elapsed * 0.0013) + 1) / 2));
            splashAt(gx, gy, -level * RIPPLE_AUDIO_GAIN * gainMul * 10);
          }
        }
        stepWave();
        draw();
      }
      raf = requestAnimationFrame(tick);
    }
    fit();
    window.addEventListener("resize", fit);
    splashAt(CALC_W * 0.5, CALC_H * 0.5, -RIPPLE_AUDIO_GAIN * gainMul * 6);
    draw();
    raf = requestAnimationFrame(tick);

    return () => {
      cancelAnimationFrame(raf);
      window.removeEventListener("resize", fit);
      gainInput.removeEventListener("input", onGainInput);
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div className={`${styles.rv} is-demo`} ref={rootRef}>
        <canvas className={styles.rv__canvas} ref={canvasRef} width={480} height={300} />
        <p className={styles.rv__caption}>합성된 오디오 레벨 곡선이 커질 때마다 이미지 표면에 물결이 세게 친다</p>
        <div className={styles.rv__control}>
          <label className={styles.rv__label} htmlFor="rvGain">반응 세기</label>
          <input
            className={styles.rv__range}
            id="rvGain"
            ref={gainRef}
            type="range"
            min={10}
            max={160}
            defaultValue={40}
            step={1}
            aria-label="반응 세기"
          />
        </div>
      </div>
    </main>
  );
}