05Pressure ripple — as a press-pressure value rises, a concentric ripple's radius and amplitude values grow together

<main class="stage">
<div class="ripple-wrap">
<button type="button" class="ripple is-demo" id="ripple" aria-pressed="false">
  <svg class="ripple__icon" viewBox="0 0 120 120" aria-hidden="true">
    <path class="ripple__wave" id="wave"></path>
    <circle class="ripple__core" cx="60" cy="60" r="10"></circle>
  </svg>
  <span class="ripple__label">Press to authenticate</span>
</button>
<p class="ripple__status" id="status">Pressure 0%</p>
</div>
</main>

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

// 계산 겹은 index.html 의 buildPath() 에 있다 — 각도마다 반지름을 사인 함수로 계산해(물결 진폭)
// 매 프레임 점을 다시 찍는다. 진폭은 포인터 압력(pointerPressure) 에 비례한다.
@include stage($stage-paper);

.ripple-wrap {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-3;
}

.ripple {
  appearance: none;
  border: none;
  background: transparent;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: $sp-3;
  cursor: pointer;
  padding: $sp-4;
  border-radius: $r-card;
  touch-action: none;

  &:focus-visible { outline: 2px solid $subject-blue-light; outline-offset: 4px; }
}

.ripple__icon {
  width: clamp(120px, 30vw, 160px);
  height: auto;
  overflow: visible;
}

.ripple__wave {
  fill: none;
  stroke: $subject-blue-light;
  stroke-width: 2.5;
}

.ripple__core {
  fill: $subject-blue-deep;
}

.ripple__label {
  color: $stage-ink;
  font-weight: 600;
  font-size: 13px;
  line-height: 1.2;
  letter-spacing: .02em;
}

.ripple__status {
  margin: 0;
  color: rgba($stage-ink, .58);
  font-weight: 500;
  font-size: 12px;
  line-height: 1.2;
}

@media (max-width: 340px) {
  .stage { padding: $sp-2; }
  .ripple-wrap { gap: $sp-2; }
  .ripple { padding: $sp-2 $sp-3; gap: $sp-2; }
  .ripple__icon { width: 104px; }
  .ripple__label { font-size: 12px; }
  .ripple__status { font-size: 11px; }
}

@media (prefers-reduced-motion: reduce) {
  .ripple__wave { transition: none; }
}

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);
}

.ripple-wrap {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
}

.ripple {
  appearance: none;
  border: none;
  background: transparent;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  cursor: pointer;
  padding: 16px;
  border-radius: 16px;
  touch-action: none;
}
.ripple:focus-visible {
  outline: 2px solid #5b8cf8;
  outline-offset: 4px;
}

.ripple__icon {
  width: clamp(120px, 30vw, 160px);
  height: auto;
  overflow: visible;
}

.ripple__wave {
  fill: none;
  stroke: #5b8cf8;
  stroke-width: 2.5;
}

.ripple__core {
  fill: #0a4fe8;
}

.ripple__label {
  color: #17141a;
  font-weight: 600;
  font-size: 13px;
  line-height: 1.2;
  letter-spacing: 0.02em;
}

.ripple__status {
  margin: 0;
  color: rgba(23, 20, 26, 0.58);
  font-weight: 500;
  font-size: 12px;
  line-height: 1.2;
}

@media (max-width: 340px) {
  .stage {
    padding: 8px;
  }
  .ripple-wrap {
    gap: 8px;
  }
  .ripple {
    padding: 8px 12px;
    gap: 8px;
  }
  .ripple__icon {
    width: 104px;
  }
  .ripple__label {
    font-size: 12px;
  }
  .ripple__status {
    font-size: 11px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .ripple__wave {
    transition: none;
  }
}

(function () {
  // 계산 겹: 물결 진폭 — 각도(θ)마다 반지름을 BASE_R + AMPLITUDE*pressure*sin(WAVE_K*θ - t*WAVE_SPEED)
  // 로 계산해 M 개 점을 매 프레임 다시 찍는다. pressure 는 실 포인터 압력(e.pressure) 또는
  // 자동 루프의 누르기-떼기 사인 곡선에서 온다 — 눌린 힘이 셀수록 물결의 진폭이 커진다.
  var BASE_R = 30;
  var AMPLITUDE = 11; // 최대 압력일 때 물결이 흔들리는 폭
  var WAVE_K = 5; // 물결 마루 개수
  var WAVE_SPEED = 0.0032; // 물결이 도는 각속도(rad/ms)
  var M = 32; // 원둘레를 따라 찍는 점 개수
  var PRESS_CYCLE_MS = 1400; // 자동 루프에서 누르기→떼기 한 번의 시간
  var GAP_MS = 500;
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  var root = document.getElementById('ripple');
  var wave = document.getElementById('wave');
  var status = document.getElementById('status');
  var isDemo = true;
  var pointerPressure = 0;
  var pointerDown = false;
  var autoStart = 0;

  function buildPath(t, pressure) {
    var d = '';
    for (var i = 0; i <= M; i++) {
      var theta = (i / M) * Math.PI * 2;
      var r = BASE_R + AMPLITUDE * pressure * Math.sin(WAVE_K * theta - t * WAVE_SPEED);
      var x = 60 + r * Math.cos(theta);
      var y = 60 + r * Math.sin(theta);
      d += (i === 0 ? 'M' : 'L') + x.toFixed(2) + ',' + y.toFixed(2) + ' ';
    }
    return d + 'Z';
  }

  function autoPressure(now) {
    if (!autoStart) autoStart = now;
    var phase = (now - autoStart) % (PRESS_CYCLE_MS + GAP_MS);
    if (phase > PRESS_CYCLE_MS) return 0;
    return Math.max(0, Math.sin((phase / PRESS_CYCLE_MS) * Math.PI));
  }

  function human() { if (isDemo) { root.classList.remove('is-demo'); isDemo = false; } }

  root.addEventListener('pointerdown', function (e) {
    human();
    pointerDown = true;
    pointerPressure = e.pressure > 0 ? e.pressure : 0.6;
    root.setAttribute('aria-pressed', 'true');
  });
  root.addEventListener('pointermove', function (e) {
    if (!pointerDown) return;
    pointerPressure = e.pressure > 0 ? e.pressure : pointerPressure;
  });
  window.addEventListener('pointerup', function () {
    if (!pointerDown) return;
    pointerDown = false;
    pointerPressure = 0;
    root.setAttribute('aria-pressed', 'false');
  });
  root.addEventListener('keydown', function (e) {
    if (e.key === ' ' || e.key === 'Enter') { human(); }
  });

  function loop(ts) {
    var reduceNow = reduce && isDemo;
    var pressure = pointerDown ? pointerPressure : (isDemo && !reduce ? autoPressure(ts) : 0);
    if (reduceNow) { pressure = 0; }
    wave.setAttribute('d', buildPath(ts, pressure));
    status.textContent = 'Pressure ' + Math.round(pressure * 100) + '%';
    requestAnimationFrame(loop);
  }
  requestAnimationFrame(loop);
})();

// PressureRipple — vanilla 판(run/371/demo/05-biometric-scan-pressure-ripple/index.html) 의 React 포트.
// 계산 겹(물결 진폭)은 usePressureRipple 훅 안에 있다: 각도(θ)마다 반지름을
// BASE_R + AMPLITUDE*pressure*sin(WAVE_K*θ - t*WAVE_SPEED) 로 계산해 매 프레임 점을 다시 찍는다.
// pressure 는 실 포인터 압력(e.pressure) 또는 자동 루프의 누르기-떼기 사인 곡선에서 온다.
import { useEffect, useRef, useState } from "react";
import styles from "./PressureRipple.module.scss";

type Box<T> = { current: T };

function usePressureRipple(
  rootRef: Box<HTMLButtonElement>,
  waveRef: Box<SVGPathElement>,
  setPressure: (p: number) => void,
  setPressed: (b: boolean) => void
) {
  useEffect(() => {
    const BASE_R = 30;
    const AMPLITUDE = 11;
    const WAVE_K = 5;
    const WAVE_SPEED = 0.0032;
    const M = 32;
    const PRESS_CYCLE_MS = 1400;
    const GAP_MS = 500;
    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;

    const root = rootRef.current;
    const wave = waveRef.current;
    if (!root || !wave) return;

    let isDemo = true;
    let pointerPressure = 0;
    let pointerDown = false;
    let autoStart = 0;
    let rafId = 0;

    function buildPath(t: number, pressure: number) {
      let d = "";
      for (let i = 0; i <= M; i++) {
        const theta = (i / M) * Math.PI * 2;
        const r = BASE_R + AMPLITUDE * pressure * Math.sin(WAVE_K * theta - t * WAVE_SPEED);
        const x = 60 + r * Math.cos(theta);
        const y = 60 + r * Math.sin(theta);
        d += (i === 0 ? "M" : "L") + x.toFixed(2) + "," + y.toFixed(2) + " ";
      }
      return d + "Z";
    }

    function autoPressure(now: number) {
      if (!autoStart) autoStart = now;
      const phase = (now - autoStart) % (PRESS_CYCLE_MS + GAP_MS);
      if (phase > PRESS_CYCLE_MS) return 0;
      return Math.max(0, Math.sin((phase / PRESS_CYCLE_MS) * Math.PI));
    }

    function human() { if (isDemo) { root.classList.remove(styles.isDemo); isDemo = false; } }

    function onPointerDown(e: PointerEvent) {
      human();
      pointerDown = true;
      pointerPressure = e.pressure > 0 ? e.pressure : 0.6;
      setPressed(true);
    }
    function onPointerMove(e: PointerEvent) {
      if (!pointerDown) return;
      pointerPressure = e.pressure > 0 ? e.pressure : pointerPressure;
    }
    function onPointerUp() {
      if (!pointerDown) return;
      pointerDown = false;
      pointerPressure = 0;
      setPressed(false);
    }
    function onKeyDown(e: KeyboardEvent) { if (e.key === " " || e.key === "Enter") human(); }

    root.addEventListener("pointerdown", onPointerDown);
    root.addEventListener("pointermove", onPointerMove);
    window.addEventListener("pointerup", onPointerUp);
    root.addEventListener("keydown", onKeyDown);

    function loop(ts: number) {
      const reduceNow = reduce && isDemo;
      let pressure = pointerDown ? pointerPressure : (isDemo && !reduce ? autoPressure(ts) : 0);
      if (reduceNow) pressure = 0;
      wave.setAttribute("d", buildPath(ts, pressure));
      setPressure(pressure);
      rafId = requestAnimationFrame(loop);
    }
    rafId = requestAnimationFrame(loop);

    return () => {
      root.removeEventListener("pointerdown", onPointerDown);
      root.removeEventListener("pointermove", onPointerMove);
      window.removeEventListener("pointerup", onPointerUp);
      root.removeEventListener("keydown", onKeyDown);
      cancelAnimationFrame(rafId);
    };
  }, []);
}

export default function PressureRipple() {
  const rootRef = useRef(null) as unknown as Box<HTMLButtonElement>;
  const waveRef = useRef(null) as unknown as Box<SVGPathElement>;
  const [pressure, setPressure] = useState(0);
  const [pressed, setPressed] = useState(false);

  usePressureRipple(rootRef, waveRef, setPressure, setPressed);

  return (
    <main className={styles.stage}>
      <div className={styles.rippleWrap}>
        <button
          type="button"
          className={styles.ripple + " " + styles.isDemo}
          ref={rootRef}
          aria-pressed={pressed}
        >
          <svg className={styles.rippleIcon} viewBox="0 0 120 120" aria-hidden="true">
            <path className={styles.rippleWave} ref={waveRef} />
            <circle className={styles.rippleCore} cx={60} cy={60} r={10} />
          </svg>
          <span className={styles.rippleLabel}>눌러서 인증</span>
        </button>
        <p className={styles.rippleStatus}>{"누르는 힘 " + Math.round(pressure * 100) + "%"}</p>
      </div>
    </main>
  );
}