05Critical-threshold pulse toggle — once a value enters a set low range, the whole bar brightens and dims on a steady rhythm

<main class="stage">
<div class="gb is-demo" id="gb">
  <div class="gb__head">
    <span class="gb__label">HP</span>
    <span class="gb__value" id="gbValue">70 / 100</span>
  </div>
  <div class="gb__track" role="progressbar" aria-label="HP" aria-valuemin="0" aria-valuemax="100" aria-valuenow="70" id="gbTrack">
    <div class="gb__fill" id="gbFill"></div>
  </div>
  <button type="button" class="gb__hit" id="gbHit">Take Damage</button>
</div>
</main>

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

// 계산 겹: index.html pulseFor() 가 잔량 v 에서 매 프레임 박동 주기·진폭을 반비례로 다시 계산한다
// (잔량이 낮을수록 주기는 짧고 진폭은 크다) — 고정 keyframe 반복이 아니다.
@include stage($stage-ink);

.gb { width: 100%; max-width: 260px; background: $subject-cream; border-radius: $r-card; padding: $sp-5; box-shadow: $shadow-raised; box-sizing: border-box; }
.gb__head { display: flex; justify-content: space-between; align-items: baseline; margin-bottom: $sp-3; }
.gb__label { font-size: 12px; font-weight: 700; letter-spacing: .04em; color: rgba($subject-ink, .72); text-transform: uppercase; }
.gb__value { font-size: 15px; font-weight: 700; color: $subject-ink; }

.gb__track { position: relative; height: 18px; border-radius: $r-pill; background: rgba($subject-ink, .1); overflow: hidden; }
.gb__fill {
  position: absolute; left: 0; top: 0; height: 100%; width: 70%; border-radius: $r-pill;
  background: $error; will-change: filter, box-shadow;
}

.gb__hit {
  margin-top: $sp-4; width: 100%; border: none; border-radius: $r-control;
  background: $subject-blue; color: $subject-cream;
  font-weight: 700; font-size: 13px; line-height: 1;
  padding: $sp-3 0; cursor: pointer;
}
.gb__hit:active { box-shadow: $shadow-press; }

@media (max-width: 340px) {
  .gb { max-width: 220px; padding: $sp-4; }
  .gb__track { height: 15px; }
  .gb__value { font-size: 13px; }
}

@media (prefers-reduced-motion: reduce) {
  .gb__fill { filter: none !important; box-shadow: none !important; }
}

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);
}

.gb {
  width: 100%;
  max-width: 260px;
  background: #fff7e6;
  border-radius: 16px;
  padding: 20px;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  box-sizing: border-box;
}

.gb__head {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 12px;
}

.gb__label {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: rgba(23, 20, 26, 0.72);
  text-transform: uppercase;
}

.gb__value {
  font-size: 15px;
  font-weight: 700;
  color: #17141a;
}

.gb__track {
  position: relative;
  height: 18px;
  border-radius: 999px;
  background: rgba(23, 20, 26, 0.1);
  overflow: hidden;
}

.gb__fill {
  position: absolute;
  left: 0;
  top: 0;
  height: 100%;
  width: 70%;
  border-radius: 999px;
  background: #c2361a;
  will-change: filter, box-shadow;
}

.gb__hit {
  margin-top: 16px;
  width: 100%;
  border: none;
  border-radius: 12px;
  background: #2f6df6;
  color: #fff7e6;
  font-weight: 700;
  font-size: 13px;
  line-height: 1;
  padding: 12px 0;
  cursor: pointer;
}

.gb__hit:active {
  box-shadow: 0 6px 12px rgba(23, 20, 26, 0.32);
}

@media (max-width: 340px) {
  .gb {
    max-width: 220px;
    padding: 16px;
  }
  .gb__track {
    height: 15px;
  }
  .gb__value {
    font-size: 13px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .gb__fill {
    filter: none !important;
    box-shadow: none !important;
  }
}

(function () {
  var HP_MAX = 100;
  var THRESHOLD = 30; // 계산 겹 상수: 위험 구간 진입 기준
  var START = 70;
  var EVENTS = [[400, -20], [1400, -15], [2200, -10], [3000, -15]]; // ms, 값 변화
  var PERIOD_MAX = 900; // ms, 임계 진입 직후(잔량 많음) 박동 주기
  var PERIOD_MIN = 280; // ms, 잔량 0 에 가까울 때 박동 주기
  var AMP_MIN = 0.12; // 임계 진입 직후 박동 진폭
  var AMP_MAX = 0.5; // 잔량 0 에 가까울 때 박동 진폭
  var HIT_LIST = [20, 15, 10, 15, 20];
  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;

  var gb = document.getElementById('gb');
  var track = document.getElementById('gbTrack');
  var fill = document.getElementById('gbFill');
  var valueEl = document.getElementById('gbValue');
  var hitBtn = document.getElementById('gbHit');

  var isDemo = true;
  var value = START;
  var appliedIdx = 0;
  var cycleStart = 0;
  var hitIdx = 0;

  function pulseFor(v, ts) {
    if (v >= THRESHOLD) return { brightness: 1, glow: 0 };
    // 계산 겹: 잔량이 낮을수록 박동 주기는 짧아지고 진폭은 커진다(반비례) — 매 프레임 v 에서 다시 계산
    var ratio = (THRESHOLD - v) / THRESHOLD; // 0..1
    var period = PERIOD_MAX - (PERIOD_MAX - PERIOD_MIN) * ratio;
    var amp = AMP_MIN + (AMP_MAX - AMP_MIN) * ratio;
    var phase = (ts % period) / period * Math.PI * 2;
    var osc = Math.sin(phase);
    return { brightness: 1 + amp * osc, glow: Math.max(0, osc) * amp };
  }

  function render(ts) {
    var v = Math.max(0, Math.min(HP_MAX, value));
    fill.style.width = v.toFixed(2) + '%';
    var p = pulseFor(v, ts);
    fill.style.filter = 'brightness(' + p.brightness.toFixed(3) + ')';
    fill.style.boxShadow = p.glow > 0.02
      ? '0 0 ' + (6 + p.glow * 18).toFixed(1) + 'px ' + (p.glow * 6).toFixed(1) + 'px rgba(255,120,90,' + p.glow.toFixed(3) + ')'
      : 'none';
    track.setAttribute('aria-valuenow', String(Math.round(v)));
    valueEl.textContent = Math.round(v) + ' / ' + HP_MAX;
  }

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

  hitBtn.addEventListener('click', function () {
    human();
    if (value <= 0) { value = START; }
    else { value = Math.max(0, value - HIT_LIST[hitIdx % HIT_LIST.length]); hitIdx++; }
    render(performance.now());
  });
  hitBtn.addEventListener('keydown', function (ev) {
    if (ev.key !== 'Enter' && ev.key !== ' ') return;
    ev.preventDefault();
    hitBtn.click();
  });

  function loop(ts) {
    if (!cycleStart) cycleStart = ts;
    var elapsed = ts - cycleStart;

    if (isDemo) {
      if (elapsed >= EVENTS[EVENTS.length - 1][0] + 1000) {
        cycleStart = ts; elapsed = 0; appliedIdx = 0; value = START;
      }
      while (appliedIdx < EVENTS.length && elapsed >= EVENTS[appliedIdx][0]) {
        value = Math.max(0, Math.min(HP_MAX, value + EVENTS[appliedIdx][1]));
        appliedIdx++;
      }
    }

    render(ts);
    requestAnimationFrame(loop);
  }

  if (!reduce) {
    requestAnimationFrame(loop);
  } else {
    render(0);
  }
})();

import { useEffect, useRef, useState } from 'react';
import styles from './GaugeBarCriticalPulse.module.scss';

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

const HP_MAX = 100;
const THRESHOLD = 30; // 계산 겹 상수: 위험 구간 진입 기준
const START = 70;
const EVENTS: [number, number][] = [[400, -20], [1400, -15], [2200, -10], [3000, -15]]; // ms, 값 변화
const PERIOD_MAX = 900; // ms, 임계 진입 직후(잔량 많음) 박동 주기
const PERIOD_MIN = 280; // ms, 잔량 0 에 가까울 때 박동 주기
const AMP_MIN = 0.12; // 임계 진입 직후 박동 진폭
const AMP_MAX = 0.5; // 잔량 0 에 가까울 때 박동 진폭
const HIT_LIST = [20, 15, 10, 15, 20];

function pulseFor(v: number, ts: number) {
  if (v >= THRESHOLD) return { brightness: 1, glow: 0 };
  // 계산 겹: 잔량이 낮을수록 박동 주기는 짧아지고 진폭은 커진다(반비례) — 매 프레임 v 에서 다시 계산
  const ratio = (THRESHOLD - v) / THRESHOLD; // 0..1
  const period = PERIOD_MAX - (PERIOD_MAX - PERIOD_MIN) * ratio;
  const amp = AMP_MIN + (AMP_MAX - AMP_MIN) * ratio;
  const phase = ((ts % period) / period) * Math.PI * 2;
  const osc = Math.sin(phase);
  return { brightness: 1 + amp * osc, glow: Math.max(0, osc) * amp };
}

export default function GaugeBarCriticalPulse() {
  const fillRef = useRef(null) as unknown as Box<HTMLDivElement>;
  const trackRef = useRef(null) as unknown as Box<HTMLDivElement>;
  const isDemoRef = useRef(true) as unknown as Box<boolean>;
  const [isDemo, setIsDemo] = useState(true);
  const [value, setValue] = useState(START);

  const valueRef = useRef(START) as unknown as Box<number>;
  const hitIdxRef = useRef(0) as unknown as Box<number>;

  function human() {
    isDemoRef.current = false;
    setIsDemo(false);
  }

  function render(ts: number) {
    const v = Math.max(0, Math.min(HP_MAX, valueRef.current));
    const fill = fillRef.current;
    const track = trackRef.current;
    if (fill) {
      fill.style.width = v.toFixed(2) + '%';
      const p = pulseFor(v, ts);
      fill.style.filter = 'brightness(' + p.brightness.toFixed(3) + ')';
      fill.style.boxShadow = p.glow > 0.02
        ? '0 0 ' + (6 + p.glow * 18).toFixed(1) + 'px ' + (p.glow * 6).toFixed(1) + 'px rgba(255,120,90,' + p.glow.toFixed(3) + ')'
        : 'none';
    }
    if (track) track.setAttribute('aria-valuenow', String(Math.round(v)));
    setValue(Math.round(v));
  }

  useEffect(() => {
    const reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
    let cycleStart = 0;
    let appliedIdx = 0;
    let rafId = 0;

    function loop(ts: number) {
      if (!cycleStart) cycleStart = ts;
      let elapsed = ts - cycleStart;

      if (isDemoRef.current) {
        if (elapsed >= EVENTS[EVENTS.length - 1][0] + 1000) {
          cycleStart = ts; elapsed = 0; appliedIdx = 0; valueRef.current = START;
        }
        while (appliedIdx < EVENTS.length && elapsed >= EVENTS[appliedIdx][0]) {
          valueRef.current = Math.max(0, Math.min(HP_MAX, valueRef.current + EVENTS[appliedIdx][1]));
          appliedIdx++;
        }
      }

      render(ts);
      rafId = requestAnimationFrame(loop);
    }

    if (!reduce) {
      rafId = requestAnimationFrame(loop);
    } else {
      render(0);
    }
    return () => cancelAnimationFrame(rafId);
  }, []);

  function onHit() {
    human();
    if (valueRef.current <= 0) { valueRef.current = START; }
    else { valueRef.current = Math.max(0, valueRef.current - HIT_LIST[hitIdxRef.current % HIT_LIST.length]); hitIdxRef.current++; }
    render(performance.now());
  }

  function onKeyDown(e: { key: string; preventDefault: () => void }) {
    if (e.key !== 'Enter' && e.key !== ' ') return;
    e.preventDefault();
    onHit();
  }

  return (
    <div className={`${styles.gb} ${isDemo ? styles.isDemo : ''}`}>
      <div className={styles.gbHead}>
        <span className={styles.gbLabel}>HP</span>
        <span className={styles.gbValue}>{value} / {HP_MAX}</span>
      </div>
      <div
        className={styles.gbTrack}
        role="progressbar"
        aria-label="HP"
        aria-valuemin={0}
        aria-valuemax={100}
        aria-valuenow={value}
        ref={trackRef}
      >
        <div className={styles.gbFill} ref={fillRef} />
      </div>
      <button type="button" className={styles.gbHit} onClick={onHit} onKeyDown={onKeyDown}>
        피해 입기
      </button>
    </div>
  );
}