09Loader Whose Inner Ring Widens Its Precession Angle With the Value

<main class="stage">
<div class="ld" id="ld">
  <p class="ld__hint">Click or press the space bar to pause or restart</p>
  <div class="ld__field" id="field" role="application" aria-label="Gyroscope precession-ring test panel" tabindex="0">
    <div class="c3__scene">
      <div class="c3__gyro" id="gyro">
        <div class="c3__ring c3__ring--outer" id="outer"></div>
        <div class="c3__ring c3__ring--inner" id="inner"></div>
      </div>
    </div>
    <b class="ld__badge" aria-hidden="true"><span class="ld__badgeNum" id="pct">0%</span><span class="ld__badgeUnit">Progress</span></b>
  </div>
</div>
</main>

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

// 자이로스코프 세차 고리 로더 — 안쪽 고리의 회전축이 진행률 값에 비례해 원뿔 모양으로 벌어지며
// 도는 세차운동(precession)을 계산한다. 바깥 고리는 고정 기울기로 계속 돌고, 안쪽 고리는
// 진행률만큼 커지는 세차각을 cos/sin 으로 두 축(X·Z)에 나눠 실어 원뿔을 그리며 돈다.
// 값이 다 차면 세차각이 가장 크게 벌어져 바깥 고리와의 차이가 가장 눈에 띈다.
// 01(문턱 인덱스 스왑)·02(정점 좌표 보간)·03(연속 순환 랭크)·04(고리별 개별 기울기)·05(구면 중심 수렴)
// ·06(면별 독립 문턱 램프)·07(회전각+거리 깊이 순위)·08(고정 가중치 필드+원근) 과 다른 축
// — 세차각을 원뿔 위상(phase)의 삼각함수로 두 축에 나눠 계산한다.

$duration: $dur-loop;
$easing: linear;
$color: $subject-blue-deep;

@include stage($stage-ink);

.ld { display: flex; flex-direction: column; gap: $sp-2; width: 100%; max-width: 360px; }

.ld__hint {
  margin: 0;
  font-weight: 700; font-size: clamp(10px, 2.8vw, 12px); line-height: 1.35;
  color: rgba($subject-cream, .78);
  text-align: center;
}

.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-blue-light; outline-offset: 2px; }

.c3__scene { position: absolute; inset: 0; perspective: clamp(320px, 70vw, 480px); }

.c3__gyro { position: absolute; left: 50%; top: 50%; width: 0; height: 0; transform-style: preserve-3d; }

.c3__ring {
  position: absolute; left: -60px; top: -60px;
  width: 120px; height: 120px;
  border-radius: 50%;
  transform-style: preserve-3d;
}
.c3__ring--outer { box-shadow: inset 0 0 0 3px rgba($subject-ink, .28); }
.c3__ring--inner {
  left: -42px; top: -42px; width: 84px; height: 84px;
  box-shadow: inset 0 0 0 3px $color;
}

.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; }
}

@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: #17141a;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.ld {
  display: flex;
  flex-direction: column;
  gap: 8px;
  width: 100%;
  max-width: 360px;
}

.ld__hint {
  margin: 0;
  font-weight: 700;
  font-size: clamp(10px, 2.8vw, 12px);
  line-height: 1.35;
  color: rgba(255, 247, 230, 0.78);
  text-align: center;
}

.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 #5b8cf8;
  outline-offset: 2px;
}

.c3__scene {
  position: absolute;
  inset: 0;
  perspective: clamp(320px, 70vw, 480px);
}

.c3__gyro {
  position: absolute;
  left: 50%;
  top: 50%;
  width: 0;
  height: 0;
  transform-style: preserve-3d;
}

.c3__ring {
  position: absolute;
  left: -60px;
  top: -60px;
  width: 120px;
  height: 120px;
  border-radius: 50%;
  transform-style: preserve-3d;
}

.c3__ring--outer {
  box-shadow: inset 0 0 0 3px rgba(23, 20, 26, 0.28);
}

.c3__ring--inner {
  left: -42px;
  top: -42px;
  width: 84px;
  height: 84px;
  box-shadow: inset 0 0 0 3px #0a4fe8;
}

.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;
  }
}

(function () {
'use strict';
var root = document.getElementById('ld');
var field = document.getElementById('field');
var pctEl = document.getElementById('pct');
var outer = document.getElementById('outer');
var inner = document.getElementById('inner');

var OUTER_TILT = 22;
var SPIN_TURNS = 1;
var PRECESSION_TURNS = 1.5;
var PRECESSION_FACTOR = 26; // 진행률이 다 찼을 때 세차각이 벌어지는 최대 각도(도) — 변형 03 대상

var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
var LOOP = 2;
var REDUCE_P = 0.7;
var t0 = 0, raf = 0, paused = false, lastP = 0;

// 안쪽 고리의 회전축이 그리는 원뿔 — 세차각(진행률에 비례해 커진다)을 원뿔 위상의 cos/sin 으로
// X축·Z축 두 방향에 나눠 실어, 축 자체가 원을 그리며 벌어지는 세차운동을 흉내 낸다.
function render(p) {
  lastP = p;
  var spinY = (p * 360 * SPIN_TURNS) % 360;
  var maxAngle = PRECESSION_FACTOR * p;
  var conePhase = (p * 360 * PRECESSION_TURNS) % 360;
  var rad = conePhase * Math.PI / 180;
  var tiltX = OUTER_TILT + maxAngle * Math.cos(rad);
  var tiltZ = maxAngle * Math.sin(rad);
  outer.style.transform = 'rotateY(' + spinY + 'deg) rotateX(' + OUTER_TILT + 'deg)';
  inner.style.transform = 'rotateY(' + spinY + 'deg) rotateX(' + tiltX + 'deg) rotateZ(' + tiltZ + 'deg)';
  pctEl.textContent = Math.round(p * 100) + '%';
}

function frame(now) {
  if (!paused) { var t = (now - t0) / 1000; render((t % LOOP) / LOOP); }
  raf = requestAnimationFrame(frame);
}
function togglePause() {
  paused = !paused;
  root.classList.toggle('is-paused', paused);
  render(reduce ? REDUCE_P : lastP);
}
function restart() {
  t0 = performance.now();
  render(reduce ? REDUCE_P : 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 () {
  if (paused || reduce) render(reduce ? REDUCE_P : lastP);
});

t0 = performance.now();
if (reduce) {
  root.classList.add('is-still');
  render(REDUCE_P);
} else {
  raf = requestAnimationFrame(frame);
}
})();

// GyroscopeRingPrecession — vanilla 판(run/399/demo/09-loader-3d-gyroscope-ring-precession/index.html) 의 React 포트.
// 안쪽 고리의 회전축이 그리는 원뿔 — 세차각(진행률에 비례해 커진다)을 원뿔 위상의 cos/sin 으로
// X축·Z축 두 방향에 나눠 실어, 축 자체가 원을 그리며 벌어지는 세차운동을 흉내 낸다.
// 01~08 과 다른 축 — 세차각을 원뿔 위상의 삼각함수로 두 축에 나눠 계산한다.
import { useEffect, useRef } from "react";
import type { CSSProperties } from "react";
import styles from "./GyroscopeRingPrecession.module.scss";

export type GyroscopeRingPrecessionProps = {
  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 };

const OUTER_TILT = 22;
const SPIN_TURNS = 1;
const PRECESSION_TURNS = 1.5;
const PRECESSION_FACTOR = 26;
const LOOP = 2;
const REDUCE_P = 0.7;
const FIELD_LABEL = "자이로스코프 세차 고리 진행 실험판";

export default function GyroscopeRingPrecession({
  duration = "2s",
  easing = "linear",
  color = "#0a4fe8",
}: GyroscopeRingPrecessionProps) {
  const rootRef = useRef<HTMLDivElement | null>(null);
  const fieldRef = useRef<HTMLDivElement | null>(null);
  const outerRef = useRef<HTMLDivElement | null>(null);
  const innerRef = useRef<HTMLDivElement | null>(null);
  const pctRef = useRef<HTMLSpanElement | null>(null);
  const pausedRef = useRef(false) as Box<boolean>;
  const lastPRef = useRef(0) as Box<number>;
  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 render(p: number): void {
    lastPRef.current = p;
    const spinY = (p * 360 * SPIN_TURNS) % 360;
    const maxAngle = PRECESSION_FACTOR * p;
    const conePhase = (p * 360 * PRECESSION_TURNS) % 360;
    const rad = (conePhase * Math.PI) / 180;
    const tiltX = OUTER_TILT + maxAngle * Math.cos(rad);
    const tiltZ = maxAngle * Math.sin(rad);
    const outer = outerRef.current;
    const inner = innerRef.current;
    if (outer) outer.style.transform = "rotateY(" + spinY + "deg) rotateX(" + OUTER_TILT + "deg)";
    if (inner) inner.style.transform = "rotateY(" + spinY + "deg) rotateX(" + tiltX + "deg) rotateZ(" + tiltZ + "deg)";
    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);
    render(reduced() ? REDUCE_P : lastPRef.current);
  }

  function restart(): void {
    t0Ref.current = performance.now();
    render(reduced() ? REDUCE_P : 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 {
    if (pausedRef.current || reduced()) render(reduced() ? REDUCE_P : lastPRef.current);
  }

  function frame(now: number): void {
    if (!pausedRef.current) {
      const t = (now - t0Ref.current) / 1000;
      render((t % LOOP) / LOOP);
    }
    rafRef.current = requestAnimationFrame(frame);
  }

  useEffect(() => {
    t0Ref.current = performance.now();
    window.addEventListener("resize", onResize);
    if (reduced()) {
      const root = rootRef.current;
      if (root) root.classList.add("is-still");
      render(REDUCE_P);
    } 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}>클릭하거나 스페이스바를 누르면 멈추거나 다시 갑니다</p>
        <div
          className={styles.field}
          ref={fieldRef}
          role="application"
          aria-label={FIELD_LABEL}
          tabIndex={0}
          onClick={onClick}
          onKeyDown={onKey}
        >
          <div className={styles.scene}>
            <div className={styles.gyro}>
              <div className={styles.ring + " " + styles.ringOuter} ref={outerRef} />
              <div className={styles.ring + " " + styles.ringInner} ref={innerRef} />
            </div>
          </div>
          <b className={styles.badge} aria-hidden="true"><span className={styles.badgeNum} ref={pctRef}>0%</span><span className={styles.badgeUnit}>진행</span></b>
        </div>
      </div>
    </main>
  );
}