01層ごとに異なる速度でずれる図形パララックス背景

<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">図形ごとに仮の距離値を持たせ、ポインターの移動量にその距離に反比例する倍率を掛けることで、近い図形は大きくずれ遠い図形はわずかしかずれない</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: 도형마다 가상 거리값(distancePx)을 갖고, 포인터 오프셋에 distanceMultiplier(거리에
  // 반비례하는 배수)를 곱해 목표 위치를 정한다. 목표 위치는 순간 이동하지 않고 매 프레임
  // INERTIA_LERP_RATE 비율로 관성 보간(lerp)해 따라간다 — 가까운 도형은 크게, 먼 도형은
  // 조금만 밀리며 부드럽게 뒤쫓는다.
  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 * 0.5;
  var PARALLAX_REF_DISTANCE_PX = 70;
  var PARALLAX_MAX_OFFSET_PX = 26;
  var INERTIA_LERP_RATE = 5.2;
  var SHAPE_COUNT = 16;

  function seedRand(seed) {
    var s = seed >>> 0;
    return function () { s = (s * 1664525 + 1013904223) >>> 0; return s / 4294967296; };
  }
  var rnd = seedRand(429011);
  var palette = ['#2f6df6', '#ff9ebb', '#4cd4a6', '#b9a0ff', '#6ec8ff'];

  function distanceMultiplier(distancePx) {
    var m = PARALLAX_REF_DISTANCE_PX / distancePx;
    return Math.max(0.18, Math.min(3.1, m));
  }

  var shapes = [];
  for (var i = 0; i < SHAPE_COUNT; i += 1) {
    var distancePx = 26 + rnd() * 150;
    var ang = rnd() * Math.PI * 2;
    var rad = 14 + rnd() * 62;
    shapes.push({
      distancePx: distancePx,
      baseX: CX + Math.cos(ang) * rad,
      baseY: CY + Math.sin(ang) * rad * 0.72,
      size: Math.max(3.2, Math.min(15, 620 / distancePx)),
      round: rnd() < 0.55,
      color: palette[i % palette.length],
      curX: 0, curY: 0
    });
  }
  shapes.sort(function (a, b) { return b.distancePx - a.distancePx; });

  var pointerNormX = 0, pointerNormY = 0;
  var pointerActive = false;

  function stepSim(dtMs) {
    var dtS = dtMs / 1000;
    var rate = Math.min(1, INERTIA_LERP_RATE * dtS);
    for (var i = 0; i < shapes.length; i += 1) {
      var s = shapes[i];
      var mult = distanceMultiplier(s.distancePx);
      var tx = pointerNormX * PARALLAX_MAX_OFFSET_PX * mult;
      var ty = pointerNormY * PARALLAX_MAX_OFFSET_PX * mult * 0.6;
      s.curX += (tx - s.curX) * rate;
      s.curY += (ty - s.curY) * rate;
    }
  }

  function drawScene() {
    var sx = cw / CALC_W, sy = ch / CALC_H;
    ctx.clearRect(0, 0, cw, ch);
    for (var i = 0; i < shapes.length; i += 1) {
      var s = shapes[i];
      var alpha = Math.max(0.35, Math.min(1, 1 - s.distancePx / 190));
      var dx = (s.baseX + s.curX) * sx, dy = (s.baseY + s.curY) * sy;
      var dr = s.size * ((sx + sy) / 2);
      ctx.globalAlpha = alpha;
      ctx.fillStyle = s.color;
      ctx.beginPath();
      if (s.round) {
        ctx.arc(dx, dy, dr, 0, Math.PI * 2);
      } else {
        ctx.save();
        ctx.translate(dx, dy);
        ctx.rotate(s.distancePx * 0.01);
        ctx.fillRect(-dr, -dr * 0.7, dr * 2, dr * 1.4);
        ctx.restore();
        ctx.beginPath();
      }
      ctx.fill();
    }
    ctx.globalAlpha = 1;
  }

  var cw = 480, ch = 300;
  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();
  }

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

  function toNorm(e) {
    var r = wrap.getBoundingClientRect();
    var t0 = (e.touches && e.touches[0]) ? e.touches[0] : e;
    return {
      x: Math.max(-1, Math.min(1, ((t0.clientX - r.left) / r.width - 0.5) * 2)),
      y: Math.max(-1, Math.min(1, ((t0.clientY - r.top) / r.height - 0.5) * 2))
    };
  }
  wrap.addEventListener('pointermove', function (e) {
    pointerActive = true;
    var n = toNorm(e);
    pointerNormX = n.x; pointerNormY = n.y;
    if (reduce) { stepSim(16); drawScene(); }
  });
  wrap.addEventListener('pointerleave', function () { pointerActive = false; });
  wrap.addEventListener('keydown', function (e) {
    var moved = true;
    if (e.key === 'ArrowLeft') pointerNormX = Math.max(-1, pointerNormX - 0.14);
    else if (e.key === 'ArrowRight') pointerNormX = Math.min(1, pointerNormX + 0.14);
    else if (e.key === 'ArrowUp') pointerNormY = Math.max(-1, pointerNormY - 0.14);
    else if (e.key === 'ArrowDown') pointerNormY = Math.min(1, pointerNormY + 0.14);
    else moved = false;
    if (moved) {
      e.preventDefault();
      pointerActive = true;
      if (reduce) { stepSim(16); drawScene(); }
    }
  });

  function virtualPointerPath(t) {
    return {
      x: Math.sin(t * 0.00072) * 0.85,
      y: Math.cos(t * 0.00104) * 0.6
    };
  }

  var elapsed = 0;
  var warmSteps = reduce ? 160 : 120;
  for (var w = 0; w < warmSteps; w += 1) {
    elapsed += 20;
    if (!pointerActive) { var v0 = virtualPointerPath(elapsed); pointerNormX = v0.x; pointerNormY = v0.y; }
    stepSim(20);
  }

  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) {
        var v = virtualPointerPath(elapsed);
        pointerNormX = v.x; pointerNormY = v.y;
      }
      stepSim(dt);
      drawScene();
    }
    requestAnimationFrame(tick);
  }
  fit();
  window.addEventListener('resize', fit);
  drawScene();
  requestAnimationFrame(tick);
})();

import { useEffect, useRef } from "react";
import styles from "./Depth3dShapeLayerParallax.module.scss";

type ShapeItem = {
  distancePx: number;
  baseX: number;
  baseY: number;
  size: number;
  round: boolean;
  color: string;
  curX: number;
  curY: number;
};

export default function Depth3dShapeLayerParallax() {
  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 * 0.5;
    const PARALLAX_REF_DISTANCE_PX = 70;
    const PARALLAX_MAX_OFFSET_PX = 26;
    const INERTIA_LERP_RATE = 5.2;
    const SHAPE_COUNT = 16;

    function seedRand(seed: number) {
      let s = seed >>> 0;
      return function () { s = (s * 1664525 + 1013904223) >>> 0; return s / 4294967296; };
    }
    const rnd = seedRand(429011);
    const palette = ["#2f6df6", "#ff9ebb", "#4cd4a6", "#b9a0ff", "#6ec8ff"];

    function distanceMultiplier(distancePx: number) {
      const m = PARALLAX_REF_DISTANCE_PX / distancePx;
      return Math.max(0.18, Math.min(3.1, m));
    }

    const shapes: ShapeItem[] = [];
    for (let i = 0; i < SHAPE_COUNT; i += 1) {
      const distancePx = 26 + rnd() * 150;
      const ang = rnd() * Math.PI * 2;
      const rad = 14 + rnd() * 62;
      shapes.push({
        distancePx,
        baseX: CX + Math.cos(ang) * rad,
        baseY: CY + Math.sin(ang) * rad * 0.72,
        size: Math.max(3.2, Math.min(15, 620 / distancePx)),
        round: rnd() < 0.55,
        color: palette[i % palette.length],
        curX: 0, curY: 0
      });
    }
    shapes.sort((a, b) => b.distancePx - a.distancePx);

    let pointerNormX = 0, pointerNormY = 0;
    let pointerActive = false;

    function stepSim(dtMs: number) {
      const dtS = dtMs / 1000;
      const rate = Math.min(1, INERTIA_LERP_RATE * dtS);
      for (let i = 0; i < shapes.length; i += 1) {
        const s = shapes[i];
        const mult = distanceMultiplier(s.distancePx);
        const tx = pointerNormX * PARALLAX_MAX_OFFSET_PX * mult;
        const ty = pointerNormY * PARALLAX_MAX_OFFSET_PX * mult * 0.6;
        s.curX += (tx - s.curX) * rate;
        s.curY += (ty - s.curY) * rate;
      }
    }

    let cw = 480, ch = 300;
    function drawScene() {
      const sx = cw / CALC_W, sy = ch / CALC_H;
      ctx!.clearRect(0, 0, cw, ch);
      for (let i = 0; i < shapes.length; i += 1) {
        const s = shapes[i];
        const alpha = Math.max(0.35, Math.min(1, 1 - s.distancePx / 190));
        const dx = (s.baseX + s.curX) * sx, dy = (s.baseY + s.curY) * sy;
        const dr = s.size * ((sx + sy) / 2);
        ctx!.globalAlpha = alpha;
        ctx!.fillStyle = s.color;
        ctx!.beginPath();
        if (s.round) {
          ctx!.arc(dx, dy, dr, 0, Math.PI * 2);
        } else {
          ctx!.save();
          ctx!.translate(dx, dy);
          ctx!.rotate(s.distancePx * 0.01);
          ctx!.fillRect(-dr, -dr * 0.7, dr * 2, dr * 1.4);
          ctx!.restore();
          ctx!.beginPath();
        }
        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();
    }

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

    function toNorm(e: PointerEvent) {
      const r = wrap.getBoundingClientRect();
      return {
        x: Math.max(-1, Math.min(1, ((e.clientX - r.left) / r.width - 0.5) * 2)),
        y: Math.max(-1, Math.min(1, ((e.clientY - r.top) / r.height - 0.5) * 2))
      };
    }
    function onPointerMove(e: PointerEvent) {
      pointerActive = true;
      const n = toNorm(e);
      pointerNormX = n.x; pointerNormY = n.y;
      if (reduce) { stepSim(16); drawScene(); }
    }
    function onPointerLeave() { pointerActive = false; }
    function onKeydown(e: KeyboardEvent) {
      let moved = true;
      if (e.key === "ArrowLeft") pointerNormX = Math.max(-1, pointerNormX - 0.14);
      else if (e.key === "ArrowRight") pointerNormX = Math.min(1, pointerNormX + 0.14);
      else if (e.key === "ArrowUp") pointerNormY = Math.max(-1, pointerNormY - 0.14);
      else if (e.key === "ArrowDown") pointerNormY = Math.min(1, pointerNormY + 0.14);
      else moved = false;
      if (moved) {
        e.preventDefault();
        pointerActive = true;
        if (reduce) { stepSim(16); drawScene(); }
      }
    }
    wrap.addEventListener("pointermove", onPointerMove);
    wrap.addEventListener("pointerleave", onPointerLeave);
    wrap.addEventListener("keydown", onKeydown);

    function virtualPointerPath(t: number) {
      return {
        x: Math.sin(t * 0.00072) * 0.85,
        y: Math.cos(t * 0.00104) * 0.6
      };
    }

    let elapsed = 0;
    const warmSteps = reduce ? 160 : 120;
    for (let w = 0; w < warmSteps; w += 1) {
      elapsed += 20;
      if (!pointerActive) { const v0 = virtualPointerPath(elapsed); pointerNormX = v0.x; pointerNormY = v0.y; }
      stepSim(20);
    }

    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) {
          const v = virtualPointerPath(elapsed);
          pointerNormX = v.x; pointerNormY = v.y;
        }
        stepSim(dt);
        drawScene();
      }
      raf = requestAnimationFrame(tick);
    }
    fit();
    window.addEventListener("resize", fit);
    drawScene();
    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}>도형마다 가상의 거리값을 부여해 포인터 이동량에 그 거리에 반비례하는 배수를 곱하고, 가까운 도형은 크게 밀리고 먼 도형은 조금만 밀린다</p>
      </div>
    </main>
  );
}