04値が上がるほどリング間の傾き差が狭まる軌道ローダー

<main class="stage">
<div class="ld" id="ld">
  <p class="ld__hint">クリックするかスペースバーを押すと一時停止または再開します</p>
  <div class="ld__field" id="field" role="application" aria-label="軌道リング傾き収束テストパネル" tabindex="0">
    <div class="c3__orbit">
      <div class="c3__ring c3__ring--0" id="r0"></div>
      <div class="c3__ring c3__ring--1" id="r1"></div>
      <div class="c3__ring c3__ring--2" id="r2"></div>
      <div class="c3__ring c3__ring--3" id="r3"></div>
    </div>
    <b class="ld__badge" aria-hidden="true"><span class="ld__badgeNum" id="pct">0%</span><span class="ld__badgeUnit">進行</span></b>
  </div>
</div>
</main>

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

// 궤도 고리 기울기 수렴 로더 — 고리마다 다른 시작 기울기(rotateX)를 두고, 진행률 값이 오르는
// 비율만큼 각 고리의 기울기를 0(정면) 쪽으로 선형 보간한다. 링마다 수렴 속도가 달라 겹치는 순간이 갈린다.
// 395(캔버스 rAF 물리)·393(포인터 tilt) 과 다른 축 — 고리마다 다른 시작 기울기를 진행률에 비례해 개별 보간한다.

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

@include stage($stage-paper);

.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: $subject-ink;
  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);
  display: grid; place-items: center;
  cursor: pointer;
  perspective: clamp(320px, 70vw, 480px);
}
.ld__field:focus-visible { outline: 2px solid $subject-blue-deep; outline-offset: 2px; }

.c3__orbit { position: relative; width: 10px; height: 10px; transform-style: preserve-3d; }

.c3__ring {
  position: absolute; left: 50%; top: 50%;
  border-radius: 50%;
  border-style: solid;
  border-color: $color;
  transform-style: preserve-3d;
  will-change: transform;
}
.c3__ring--0 { width: 168px; height: 168px; margin: -84px 0 0 -84px; border-width: 3px; opacity: 1; }
.c3__ring--1 { width: 138px; height: 138px; margin: -69px 0 0 -69px; border-width: 3px; opacity: .82; border-color: mix($color, $subject-cream, 80%); }
.c3__ring--2 { width: 108px; height: 108px; margin: -54px 0 0 -54px; border-width: 3px; opacity: .64; border-color: mix($color, $subject-cream, 62%); }
.c3__ring--3 { width: 78px;  height: 78px;  margin: -39px 0 0 -39px; border-width: 3px; opacity: .48; border-color: mix($color, $subject-cream, 46%); }

.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; }
  .c3__ring--0 { width: 108px; height: 108px; margin: -54px 0 0 -54px; }
  .c3__ring--1 { width: 90px; height: 90px; margin: -45px 0 0 -45px; }
  .c3__ring--2 { width: 72px; height: 72px; margin: -36px 0 0 -36px; }
  .c3__ring--3 { width: 52px; height: 52px; margin: -26px 0 0 -26px; }
  .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: #ffffff;
  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: #17141a;
  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);
  display: grid;
  place-items: center;
  cursor: pointer;
  perspective: clamp(320px, 70vw, 480px);
}

.ld__field:focus-visible {
  outline: 2px solid #0a4fe8;
  outline-offset: 2px;
}

.c3__orbit {
  position: relative;
  width: 10px;
  height: 10px;
  transform-style: preserve-3d;
}

.c3__ring {
  position: absolute;
  left: 50%;
  top: 50%;
  border-radius: 50%;
  border-style: solid;
  border-color: #0a4fe8;
  transform-style: preserve-3d;
  will-change: transform;
}

.c3__ring--0 {
  width: 168px;
  height: 168px;
  margin: -84px 0 0 -84px;
  border-width: 3px;
  opacity: 1;
}

.c3__ring--1 {
  width: 138px;
  height: 138px;
  margin: -69px 0 0 -69px;
  border-width: 3px;
  opacity: 0.82;
  border-color: rgb(23.137254902%, 44.1568627451%, 90.8235294118%);
}

.c3__ring--2 {
  width: 108px;
  height: 108px;
  margin: -54px 0 0 -54px;
  border-width: 3px;
  opacity: 0.64;
  border-color: rgb(40.431372549%, 56.0156862745%, 90.6823529412%);
}

.c3__ring--3 {
  width: 78px;
  height: 78px;
  margin: -39px 0 0 -39px;
  border-width: 3px;
  opacity: 0.48;
  border-color: rgb(55.8039215686%, 66.5568627451%, 90.5568627451%);
}

.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;
  }
  .c3__ring--0 {
    width: 108px;
    height: 108px;
    margin: -54px 0 0 -54px;
  }
  .c3__ring--1 {
    width: 90px;
    height: 90px;
    margin: -45px 0 0 -45px;
  }
  .c3__ring--2 {
    width: 72px;
    height: 72px;
    margin: -36px 0 0 -36px;
  }
  .c3__ring--3 {
    width: 52px;
    height: 52px;
    margin: -26px 0 0 -26px;
  }
  .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 rings = [document.getElementById('r0'), document.getElementById('r1'), document.getElementById('r2'), document.getElementById('r3')];

var INITIAL_TILT = [72, 54, 36, 18]; // 고리마다 다른 시작 기울기(deg) — 값이 오를수록 0 으로 수렴
var SPIN_TURNS = 0.6;                 // 한 루프 동안 고리 묶음이 도는 회전수

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;

function render(p) {
  lastP = p;
  var spinY = (p * 360 * SPIN_TURNS) % 360;
  for (var i = 0; i < rings.length; i++) {
    var tilt = INITIAL_TILT[i] * (1 - p); // 정면 각도(0deg) 쪽으로 진행률 비례 보간
    rings[i].style.transform = 'rotateY(' + spinY + 'deg) rotateX(' + tilt + '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);
}
})();

// RingOrbitTiltStack — vanilla 판(run/399/demo/04-loader-3d-ring-orbit-tilt-stack/index.html) 의 React 포트.
// 고리마다 다른 시작 기울기(rotateX)를 진행률 비율만큼 0(정면) 으로 개별 보간한다.
// 395(캔버스 rAF 물리)·393(포인터 tilt) 과 다른 축 — 고리마다 다른 시작 기울기를 진행률에 비례해 개별 보간한다.
import { useEffect, useRef } from "react";
import type { CSSProperties } from "react";
import styles from "./RingOrbitTiltStack.module.scss";

export type RingOrbitTiltStackProps = {
  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 INITIAL_TILT = [72, 54, 36, 18];
const SPIN_TURNS = 0.6;
const LOOP = 2;
const REDUCE_P = 0.7;
const FIELD_LABEL = "궤도 고리 기울기 수렴 진행 실험판";

export default function RingOrbitTiltStack({
  duration = "2s",
  easing = "cubic-bezier(.2,.8,.2,1)",
  color = "#0a4fe8",
}: RingOrbitTiltStackProps) {
  const rootRef = useRef<HTMLDivElement | null>(null);
  const fieldRef = useRef<HTMLDivElement | null>(null);
  const pctRef = useRef<HTMLSpanElement | null>(null);
  const ringsRef = useRef<(HTMLDivElement | null)[]>([null, null, null, null]) as Box<(HTMLDivElement | 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 };
  const ringClasses = [styles.ring0, styles.ring1, styles.ring2, styles.ring3];

  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 rings = ringsRef.current;
    for (let i = 0; i < rings.length; i++) {
      const el = rings[i];
      if (!el) continue;
      const tilt = INITIAL_TILT[i] * (1 - p);
      el.style.transform = "rotateY(" + spinY + "deg) rotateX(" + tilt + "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.orbit}>
            {[0, 1, 2, 3].map((i) => (
              <div key={i} className={styles.ring + " " + ringClasses[i]} ref={(el: HTMLDivElement | null) => { ringsRef.current[i] = el; }} />
            ))}
          </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>
  );
}