05ポインターに合わせて傾く軌道衛星リング

<main class="stage">
<div class="d3 is-demo" id="d3Root" tabindex="0">
  <canvas class="d3__canvas" id="d3Canvas" width="480" height="300"></canvas>
  <p class="d3__caption">小さな図形の位置を球面座標の式で毎フレーム計算しz値の順に描き直すことで、ポインター位置に応じてリング全体が傾きながらも前後の重なりが正しく保たれる</p>
</div>
</main>

@use "../../../../site/static/demo-tokens" as *;
@include stage($stage-ink);

.d3 {
  position: relative;
  width: min(92vw, calc(160vh - 12.8vw));
  aspect-ratio: 480 / 300;
  margin: 0 auto;
  border-radius: $r-card;
  overflow: hidden;
  box-shadow: $shadow-raised;
  background: $stage-ink;
  outline: none;
}

.d3__canvas {
  display: block;
  width: 100%;
  height: 100%;
}

.d3__caption {
  position: absolute;
  left: $sp-3;
  bottom: $sp-3;
  max-width: 78%;
  margin: 0;
  padding: $sp-1 $sp-3;
  border-radius: $r-pill;
  background: rgba(255, 255, 255, .85);
  color: $subject-ink;
  font-weight: 500;
  font-size: 12px;
  line-height: 1.4;
  pointer-events: none;
}

@media (max-width: 340px) {
  .d3__caption { font-size: 10px; padding: $sp-1 $sp-2; }
}

@media (prefers-reduced-motion: reduce) {
  .d3 { cursor: default; }
}

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);
}

.d3 {
  position: relative;
  width: min(92vw, 160vh - 12.8vw);
  aspect-ratio: 480/300;
  margin: 0 auto;
  border-radius: 16px;
  overflow: hidden;
  box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
  background: #17141a;
  outline: none;
}

.d3__canvas {
  display: block;
  width: 100%;
  height: 100%;
}

.d3__caption {
  position: absolute;
  left: 12px;
  bottom: 12px;
  max-width: 78%;
  margin: 0;
  padding: 4px 12px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.85);
  color: #17141a;
  font-weight: 500;
  font-size: 12px;
  line-height: 1.4;
  pointer-events: none;
}

@media (max-width: 340px) {
  .d3__caption {
    font-size: 10px;
    padding: 4px 8px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .d3 {
    cursor: default;
  }
}

(function () {
  // 기법: 위성마다 satelliteAngleAt 로 궤도각을 구해 고리 평면(XZ) 위 좌표를 얻은 뒤, 포인터로
  // 정해지는 tiltDeg(최대 ORBIT_TILT_MAX_DEG) 만큼 X축 회전을 적용해 y·z 를 다시 계산한다.
  // 회전 뒤 z값(깊이) 기준으로 zSortSatellites 가 매 프레임 다시 정렬해 뒤에서 앞 순서로 그려야
  // 고리가 기울어도 앞뒤 가림이 맞는다(화가 알고리즘).
  var root = document.getElementById('d3Root');
  var canvas = document.getElementById('d3Canvas');
  var ctx = canvas.getContext('2d');
  var wrap = canvas.parentElement;

  var CALC_W = 160, CALC_H = 100;
  var CX = CALC_W * 0.5, CY = CALC_H * 0.52;
  var RING_RADIUS = 40;
  var ORBIT_TILT_MAX_DEG = 18;
  var SAT_COUNT = 9;
  var ANGULAR_SPEED = 0.00062;

  function seedRand(seed) {
    var s = seed >>> 0;
    return function () { s = (s * 1664525 + 1013904223) >>> 0; return s / 4294967296; };
  }
  var rnd = seedRand(429051);
  var palette = ['#6ec8ff', '#b9a0ff', '#ff9ebb', '#4cd4a6', '#ffd23f'];

  var satellites = [];
  for (var i = 0; i < SAT_COUNT; i += 1) {
    satellites.push({
      baseAngle: (Math.PI * 2 / SAT_COUNT) * i + rnd() * 0.3,
      radiusScale: 0.72 + rnd() * 0.32,
      size: 3.2 + rnd() * 3.4,
      color: palette[i % palette.length]
    });
  }

  function satelliteAngleAt(sat, t) {
    return sat.baseAngle + t * ANGULAR_SPEED;
  }

  var tiltDeg = 0, azimuthOffset = 0;
  var pointerActive = false;

  function computeTransformed(sat, t) {
    var ang = satelliteAngleAt(sat, t) + azimuthOffset;
    var r = RING_RADIUS * sat.radiusScale;
    var lx = Math.cos(ang) * r;
    var lz = Math.sin(ang) * r;
    var tiltRad = tiltDeg * Math.PI / 180;
    var ry = -lz * Math.sin(tiltRad);
    var rz = lz * Math.cos(tiltRad);
    return { x: lx, y: ry, z: rz };
  }

  function zSortSatellites(list, t) {
    var withZ = list.map(function (sat) {
      var p = computeTransformed(sat, t);
      return { sat: sat, p: p };
    });
    withZ.sort(function (a, b) { return a.p.z - b.p.z; });
    return withZ;
  }

  var elapsed = 0;
  var cw = 480, ch = 300;

  function drawScene(nowMs) {
    var sx = cw / CALC_W, sy = ch / CALC_H;
    var savg = (sx + sy) / 2;
    ctx.clearRect(0, 0, cw, ch);

    ctx.fillStyle = 'rgba(150,170,255,.14)';
    ctx.beginPath();
    ctx.arc(CX * sx, CY * sy, RING_RADIUS * 0.5 * savg, 0, Math.PI * 2);
    ctx.fill();

    var ordered = zSortSatellites(satellites, nowMs);
    for (var i = 0; i < ordered.length; i += 1) {
      var p = ordered[i].p;
      var sat = ordered[i].sat;
      var perspScale = Math.max(0.55, Math.min(1.5, 1 + p.z / RING_RADIUS * 0.45));
      var alpha = Math.max(0.4, Math.min(1, 0.62 + p.z / RING_RADIUS * 0.4));
      var dx = (CX + p.x) * sx, dy = (CY + p.y) * sy;
      var dr = sat.size * perspScale * savg;
      ctx.globalAlpha = alpha;
      ctx.fillStyle = sat.color;
      ctx.beginPath();
      ctx.arc(dx, dy, dr, 0, Math.PI * 2);
      ctx.fill();
    }
    ctx.globalAlpha = 1;
  }

  function fit() {
    var r = wrap.getBoundingClientRect();
    cw = Math.max(1, Math.round(r.width));
    ch = Math.max(1, Math.round(r.height));
    canvas.width = cw; canvas.height = ch;
    drawScene(elapsed);
  }

  var reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
  if (reduce) root.classList.remove('is-demo');

  wrap.addEventListener('pointermove', function (e) {
    pointerActive = true;
    var r = wrap.getBoundingClientRect();
    var ny = ((e.clientY - r.top) / r.height - 0.5) * 2;
    var nx = ((e.clientX - r.left) / r.width - 0.5) * 2;
    tiltDeg = Math.max(-ORBIT_TILT_MAX_DEG, Math.min(ORBIT_TILT_MAX_DEG, ny * ORBIT_TILT_MAX_DEG));
    azimuthOffset = nx * 0.9;
    if (reduce) drawScene(elapsed);
  });
  wrap.addEventListener('pointerleave', function () { pointerActive = false; });
  wrap.addEventListener('keydown', function (e) {
    var moved = true;
    if (e.key === 'ArrowUp') tiltDeg = Math.max(-ORBIT_TILT_MAX_DEG, tiltDeg - 3);
    else if (e.key === 'ArrowDown') tiltDeg = Math.min(ORBIT_TILT_MAX_DEG, tiltDeg + 3);
    else if (e.key === 'ArrowLeft') azimuthOffset -= 0.16;
    else if (e.key === 'ArrowRight') azimuthOffset += 0.16;
    else moved = false;
    if (moved) {
      e.preventDefault();
      pointerActive = true;
      if (reduce) drawScene(elapsed);
    }
  });

  function virtualTiltAt(t) {
    return Math.sin(t * 0.00058) * ORBIT_TILT_MAX_DEG;
  }

  var warmSteps = reduce ? 0 : 100;
  for (var w = 0; w < warmSteps; w += 1) {
    elapsed += 20;
    if (!pointerActive) tiltDeg = virtualTiltAt(elapsed);
  }

  var lastTs = null;
  function tick(ts) {
    if (lastTs === null) lastTs = ts;
    var dt = Math.min(ts - lastTs, 48);
    lastTs = ts;
    if (!reduce) {
      elapsed += dt;
      if (!pointerActive) tiltDeg = virtualTiltAt(elapsed);
      drawScene(elapsed);
    }
    requestAnimationFrame(tick);
  }
  fit();
  window.addEventListener('resize', fit);
  drawScene(elapsed);
  requestAnimationFrame(tick);
})();

import { useEffect, useRef } from "react";
import styles from "./Depth3dOrbitRingSatellites.module.scss";

type Satellite = {
  baseAngle: number;
  radiusScale: number;
  size: number;
  color: string;
};

export default function Depth3dOrbitRingSatellites() {
  const rootRef = useRef<HTMLDivElement>(null);
  const canvasRef = useRef<HTMLCanvasElement>(null);

  useEffect(() => {
    const root = rootRef.current;
    const canvas = canvasRef.current;
    if (!root || !canvas) return;
    const ctx = canvas.getContext("2d");
    if (!ctx) return;
    const wrap = canvas.parentElement as HTMLElement;

    const CALC_W = 160, CALC_H = 100;
    const CX = CALC_W * 0.5, CY = CALC_H * 0.52;
    const RING_RADIUS = 40;
    const ORBIT_TILT_MAX_DEG = 18;
    const SAT_COUNT = 9;
    const ANGULAR_SPEED = 0.00062;

    function seedRand(seed: number) {
      let s = seed >>> 0;
      return function () { s = (s * 1664525 + 1013904223) >>> 0; return s / 4294967296; };
    }
    const rnd = seedRand(429051);
    const palette = ["#6ec8ff", "#b9a0ff", "#ff9ebb", "#4cd4a6", "#ffd23f"];

    const satellites: Satellite[] = [];
    for (let i = 0; i < SAT_COUNT; i += 1) {
      satellites.push({
        baseAngle: (Math.PI * 2 / SAT_COUNT) * i + rnd() * 0.3,
        radiusScale: 0.72 + rnd() * 0.32,
        size: 3.2 + rnd() * 3.4,
        color: palette[i % palette.length]
      });
    }

    function satelliteAngleAt(sat: Satellite, t: number) {
      return sat.baseAngle + t * ANGULAR_SPEED;
    }

    let tiltDeg = 0, azimuthOffset = 0;
    let pointerActive = false;

    function computeTransformed(sat: Satellite, t: number) {
      const ang = satelliteAngleAt(sat, t) + azimuthOffset;
      const r = RING_RADIUS * sat.radiusScale;
      const lx = Math.cos(ang) * r;
      const lz = Math.sin(ang) * r;
      const tiltRad = tiltDeg * Math.PI / 180;
      const ry = -lz * Math.sin(tiltRad);
      const rz = lz * Math.cos(tiltRad);
      return { x: lx, y: ry, z: rz };
    }

    function zSortSatellites(list: Satellite[], t: number) {
      const withZ = list.map((sat) => ({ sat, p: computeTransformed(sat, t) }));
      withZ.sort((a, b) => a.p.z - b.p.z);
      return withZ;
    }

    let elapsed = 0;
    let cw = 480, ch = 300;

    function drawScene(nowMs: number) {
      const sx = cw / CALC_W, sy = ch / CALC_H;
      const savg = (sx + sy) / 2;
      ctx!.clearRect(0, 0, cw, ch);

      ctx!.fillStyle = "rgba(150,170,255,.14)";
      ctx!.beginPath();
      ctx!.arc(CX * sx, CY * sy, RING_RADIUS * 0.5 * savg, 0, Math.PI * 2);
      ctx!.fill();

      const ordered = zSortSatellites(satellites, nowMs);
      for (let i = 0; i < ordered.length; i += 1) {
        const p = ordered[i].p;
        const sat = ordered[i].sat;
        const perspScale = Math.max(0.55, Math.min(1.5, 1 + p.z / RING_RADIUS * 0.45));
        const alpha = Math.max(0.4, Math.min(1, 0.62 + p.z / RING_RADIUS * 0.4));
        const dx = (CX + p.x) * sx, dy = (CY + p.y) * sy;
        const dr = sat.size * perspScale * savg;
        ctx!.globalAlpha = alpha;
        ctx!.fillStyle = sat.color;
        ctx!.beginPath();
        ctx!.arc(dx, dy, dr, 0, Math.PI * 2);
        ctx!.fill();
      }
      ctx!.globalAlpha = 1;
    }

    function fit() {
      const r = wrap.getBoundingClientRect();
      cw = Math.max(1, Math.round(r.width));
      ch = Math.max(1, Math.round(r.height));
      canvas!.width = cw; canvas!.height = ch;
      drawScene(elapsed);
    }

    const reduce = window.matchMedia("(prefers-reduced-motion: reduce)").matches;
    if (reduce) root.classList.remove("is-demo");

    function onPointerMove(e: PointerEvent) {
      pointerActive = true;
      const r = wrap.getBoundingClientRect();
      const ny = ((e.clientY - r.top) / r.height - 0.5) * 2;
      const nx = ((e.clientX - r.left) / r.width - 0.5) * 2;
      tiltDeg = Math.max(-ORBIT_TILT_MAX_DEG, Math.min(ORBIT_TILT_MAX_DEG, ny * ORBIT_TILT_MAX_DEG));
      azimuthOffset = nx * 0.9;
      if (reduce) drawScene(elapsed);
    }
    function onPointerLeave() { pointerActive = false; }
    function onKeydown(e: KeyboardEvent) {
      let moved = true;
      if (e.key === "ArrowUp") tiltDeg = Math.max(-ORBIT_TILT_MAX_DEG, tiltDeg - 3);
      else if (e.key === "ArrowDown") tiltDeg = Math.min(ORBIT_TILT_MAX_DEG, tiltDeg + 3);
      else if (e.key === "ArrowLeft") azimuthOffset -= 0.16;
      else if (e.key === "ArrowRight") azimuthOffset += 0.16;
      else moved = false;
      if (moved) {
        e.preventDefault();
        pointerActive = true;
        if (reduce) drawScene(elapsed);
      }
    }
    wrap.addEventListener("pointermove", onPointerMove);
    wrap.addEventListener("pointerleave", onPointerLeave);
    wrap.addEventListener("keydown", onKeydown);

    function virtualTiltAt(t: number) {
      return Math.sin(t * 0.00058) * ORBIT_TILT_MAX_DEG;
    }

    const warmSteps = reduce ? 0 : 100;
    for (let w = 0; w < warmSteps; w += 1) {
      elapsed += 20;
      if (!pointerActive) tiltDeg = virtualTiltAt(elapsed);
    }

    let lastTs: number | null = null;
    let raf = 0;
    function tick(ts: number) {
      if (lastTs === null) lastTs = ts;
      const dt = Math.min(ts - lastTs, 48);
      lastTs = ts;
      if (!reduce) {
        elapsed += dt;
        if (!pointerActive) tiltDeg = virtualTiltAt(elapsed);
        drawScene(elapsed);
      }
      raf = requestAnimationFrame(tick);
    }
    fit();
    window.addEventListener("resize", fit);
    drawScene(elapsed);
    raf = requestAnimationFrame(tick);

    return () => {
      cancelAnimationFrame(raf);
      window.removeEventListener("resize", fit);
      wrap.removeEventListener("pointermove", onPointerMove);
      wrap.removeEventListener("pointerleave", onPointerLeave);
      wrap.removeEventListener("keydown", onKeydown);
    };
  }, []);

  return (
    <main className={styles.stage}>
      <div className={`${styles.d3} is-demo`} ref={rootRef} tabIndex={0}>
        <canvas className={styles.d3__canvas} ref={canvasRef} width={480} height={300} />
        <p className={styles.d3__caption}>작은 도형들의 위치를 구면 좌표식으로 매 프레임 계산하고 z값 순서로 다시 그려, 포인터 위치에 따라 고리 전체가 기울면서도 앞뒤 가림이 맞는다</p>
      </div>
    </main>
  );
}