02Loader Whose Wireframe Vertices Settle Into Place With the Progress 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="Wireframe vertex convergence test panel" tabindex="0">
    <div class="c3__scene">
      <div class="c3__cube" id="c3cube">
        <svg class="c3__svg" id="svg">
          <line class="c3__edge" id="e0"></line><line class="c3__edge" id="e1"></line>
          <line class="c3__edge" id="e2"></line><line class="c3__edge" id="e3"></line>
          <line class="c3__edge" id="e4"></line><line class="c3__edge" id="e5"></line>
          <line class="c3__edge" id="e6"></line><line class="c3__edge" id="e7"></line>
          <line class="c3__edge" id="e8"></line><line class="c3__edge" id="e9"></line>
          <line class="c3__edge" id="e10"></line><line class="c3__edge" id="e11"></line>
        </svg>
        <div class="c3__vtx" id="v0"></div><div class="c3__vtx" id="v1"></div>
        <div class="c3__vtx" id="v2"></div><div class="c3__vtx" id="v3"></div>
        <div class="c3__vtx" id="v4"></div><div class="c3__vtx" id="v5"></div>
        <div class="c3__vtx" id="v6"></div><div class="c3__vtx" id="v7"></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 *;

// 와이어프레임 정점 수렴 로더 — 시작 위치(고정 산점 배열)에서 목표 정점(정육면체 모서리)까지
// 진행률(0~1)을 지수 곡선(ease)으로 눌러 보간하고, 매 프레임 getBoundingClientRect() 로
// preserve-3d 가 투영한 실제 화면 좌표를 읽어 SVG 선을 다시 그린다.
// 395(캔버스 rAF 물리)·393(포인터 tilt) 과 다른 축 — 3D 투영 결과의 실측 좌표로 2D 선을 그린다.

$duration: $dur-loop;
$easing: linear;
$color: $subject-ink;

@include stage($stage-yellow);

.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: $stage-paper;
  box-shadow: inset 0 0 0 1px rgba($subject-ink, .16);
  cursor: pointer;
}
.ld__field:focus-visible { outline: 2px solid $subject-blue-deep; outline-offset: 2px; }

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

.c3__cube {
  position: absolute; left: 50%; top: 50%;
  width: 0; height: 0;
  transform-style: preserve-3d;
}

.c3__vtx {
  position: absolute; left: 0; top: 0;
  width: 9px; height: 9px; margin: -4.5px 0 0 -4.5px;
  border-radius: 50%;
  background: $color;
  will-change: transform, opacity;
}

.c3__svg {
  position: absolute; inset: 0;
  width: 100%; height: 100%;
  pointer-events: none;
}
.c3__edge { stroke: $color; stroke-width: 1.6; }

.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: #ffd23f;
  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: #ffffff;
  box-shadow: inset 0 0 0 1px rgba(23, 20, 26, 0.16);
  cursor: pointer;
}

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

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

.c3__cube {
  position: absolute;
  left: 50%;
  top: 50%;
  width: 0;
  height: 0;
  transform-style: preserve-3d;
}

.c3__vtx {
  position: absolute;
  left: 0;
  top: 0;
  width: 9px;
  height: 9px;
  margin: -4.5px 0 0 -4.5px;
  border-radius: 50%;
  background: #17141a;
  will-change: transform, opacity;
}

.c3__svg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
}

.c3__edge {
  stroke: #17141a;
  stroke-width: 1.6;
}

.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 cube = document.getElementById('c3cube');
var vtx = [];
for (var vi = 0; vi < 8; vi++) vtx.push(document.getElementById('v' + vi));
var lines = [];
for (var li = 0; li < 12; li++) lines.push(document.getElementById('e' + li));

// 정육면체 모서리(정점 인덱스 비트: 0=x·1=y·2=z, -/+)
var EDGES = [[0,1],[0,2],[0,4],[1,3],[1,5],[2,3],[2,6],[3,7],[4,5],[4,6],[5,7],[6,7]];
var HALF = 42;
var TARGETS = [];
for (var ti = 0; ti < 8; ti++) {
  TARGETS.push([(ti & 1) ? HALF : -HALF, (ti & 2) ? HALF : -HALF, (ti & 4) ? HALF : -HALF]);
}
// 시작 산점 좌표 — 고정 배열(실호출 Math.random 없음)
var SCATTER = [
  [-70, -55, 10], [60, -65, -20], [-50, 60, 30], [75, 50, -10],
  [-65, -30, -40], [55, -20, 45], [-40, 65, -25], [65, 70, 15]
];

var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
var LOOP = 2;
var REDUCE_P = 0.7;
var LERP_EASE_POW = 1.8; // 정점 수렴 곡선 지수 — 변형 02 대상 (클수록 막판에 몰려 맺힌다)
var ROT_TURNS = 1;        // 한 루프 동안 큐브가 도는 회전수
var t0 = 0, raf = 0, paused = false, lastP = 0;

function ease(p) { return Math.pow(p, LERP_EASE_POW); }

function updateLines(e) {
  var fr = field.getBoundingClientRect();
  for (var i = 0; i < 12; i++) {
    var a = vtx[EDGES[i][0]].getBoundingClientRect();
    var b = vtx[EDGES[i][1]].getBoundingClientRect();
    var ax = a.left + a.width / 2 - fr.left;
    var ay = a.top + a.height / 2 - fr.top;
    var bx = b.left + b.width / 2 - fr.left;
    var by = b.top + b.height / 2 - fr.top;
    var ln = lines[i];
    ln.setAttribute('x1', ax); ln.setAttribute('y1', ay);
    ln.setAttribute('x2', bx); ln.setAttribute('y2', by);
    ln.setAttribute('stroke-opacity', String(0.15 + 0.85 * e));
  }
}

function render(p) {
  lastP = p;
  var e = ease(p);
  var rotY = (p * 360 * ROT_TURNS) % 360;
  cube.style.transform = 'rotateX(18deg) rotateY(' + rotY + 'deg)';
  for (var i = 0; i < 8; i++) {
    var sx = SCATTER[i][0], sy = SCATTER[i][1], sz = SCATTER[i][2];
    var tx = TARGETS[i][0], ty = TARGETS[i][1], tz = TARGETS[i][2];
    var cx = sx + (tx - sx) * e;
    var cy = sy + (ty - sy) * e;
    var cz = sz + (tz - sz) * e;
    vtx[i].style.transform = 'translate3d(' + cx + 'px,' + cy + 'px,' + cz + 'px)';
    vtx[i].style.opacity = String(0.25 + 0.75 * e);
  }
  updateLines(e);
  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);
}
})();

// WireframeVertexSnap — vanilla 판(run/399/demo/02-loader-3d-wireframe-vertex-snap/index.html) 의 React 포트.
// 시작 산점 좌표(고정 배열)에서 목표 정육면체 모서리까지 진행률을 지수 곡선(ease)으로 보간하고,
// 매 프레임 getBoundingClientRect() 로 preserve-3d 가 투영한 실제 화면 좌표를 읽어 SVG 선을 다시 그린다.
import { useEffect, useRef } from "react";
import type { CSSProperties } from "react";
import styles from "./WireframeVertexSnap.module.scss";

export type WireframeVertexSnapProps = {
  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 EDGES: [number, number][] = [[0,1],[0,2],[0,4],[1,3],[1,5],[2,3],[2,6],[3,7],[4,5],[4,6],[5,7],[6,7]];
const HALF = 42;
const TARGETS: [number, number, number][] = [0,1,2,3,4,5,6,7].map((i) => [
  (i & 1) ? HALF : -HALF, (i & 2) ? HALF : -HALF, (i & 4) ? HALF : -HALF,
]);
const SCATTER: [number, number, number][] = [
  [-70, -55, 10], [60, -65, -20], [-50, 60, 30], [75, 50, -10],
  [-65, -30, -40], [55, -20, 45], [-40, 65, -25], [65, 70, 15],
];
const LOOP = 2;
const REDUCE_P = 0.7;
const LERP_EASE_POW = 1.8; // 정점 수렴 곡선 지수 — 변형 02 대상
const ROT_TURNS = 1;
const FIELD_LABEL = "와이어프레임 정점 수렴 진행 실험판";

export default function WireframeVertexSnap({
  duration = "2s",
  easing = "linear",
  color = "#17141a",
}: WireframeVertexSnapProps) {
  const rootRef = useRef<HTMLDivElement | null>(null);
  const fieldRef = useRef<HTMLDivElement | null>(null);
  const cubeRef = useRef<HTMLDivElement | null>(null);
  const pctRef = useRef<HTMLSpanElement | null>(null);
  const vtxRef = useRef<(HTMLDivElement | null)[]>([null, null, null, null, null, null, null, null]) as Box<(HTMLDivElement | null)[]>;
  const lineRef = useRef<(SVGLineElement | null)[]>(new Array(12).fill(null)) as Box<(SVGLineElement | 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 ease(p: number): number {
    return Math.pow(p, LERP_EASE_POW);
  }

  function updateLines(e: number): void {
    const field = fieldRef.current;
    const vtx = vtxRef.current;
    const lines = lineRef.current;
    if (!field) return;
    const fr = field.getBoundingClientRect();
    for (let i = 0; i < 12; i++) {
      const av = vtx[EDGES[i][0]];
      const bv = vtx[EDGES[i][1]];
      const ln = lines[i];
      if (!av || !bv || !ln) continue;
      const a = av.getBoundingClientRect();
      const b = bv.getBoundingClientRect();
      const ax = a.left + a.width / 2 - fr.left;
      const ay = a.top + a.height / 2 - fr.top;
      const bx = b.left + b.width / 2 - fr.left;
      const by = b.top + b.height / 2 - fr.top;
      ln.setAttribute("x1", String(ax));
      ln.setAttribute("y1", String(ay));
      ln.setAttribute("x2", String(bx));
      ln.setAttribute("y2", String(by));
      ln.setAttribute("stroke-opacity", String(0.15 + 0.85 * e));
    }
  }

  function render(p: number): void {
    lastPRef.current = p;
    const e = ease(p);
    const cube = cubeRef.current;
    const rotY = (p * 360 * ROT_TURNS) % 360;
    if (cube) cube.style.transform = "rotateX(18deg) rotateY(" + rotY + "deg)";
    const vtx = vtxRef.current;
    for (let i = 0; i < 8; i++) {
      const el = vtx[i];
      if (!el) continue;
      const [sx, sy, sz] = SCATTER[i];
      const [tx, ty, tz] = TARGETS[i];
      const cx = sx + (tx - sx) * e;
      const cy = sy + (ty - sy) * e;
      const cz = sz + (tz - sz) * e;
      el.style.transform = "translate3d(" + cx + "px," + cy + "px," + cz + "px)";
      el.style.opacity = String(0.25 + 0.75 * e);
    }
    updateLines(e);
    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.cube} ref={cubeRef}>
              <svg className={styles.svg}>
                {EDGES.map((_, i) => (
                  <line key={i} className={styles.edge} ref={(el: SVGLineElement | null) => { lineRef.current[i] = el; }} />
                ))}
              </svg>
              {[0, 1, 2, 3, 4, 5, 6, 7].map((i) => (
                <div key={i} className={styles.vtx} ref={(el: HTMLDivElement | null) => { vtxRef.current[i] = el; }} />
              ))}
            </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>
  );
}