Parallax Unzoom

<!--
  Parallax Unzoom — focus card scales down from full frame while siblings
  parallax IN to form a grid. The reverse of parallax-zoom.

  Pairs naturally with parallax-zoom: zoom INTO a card in scene 1, then
  unzoom OUT of it in scene 2 to reveal a fresh grid underneath.

  Usage:
  1. Wrap your card grid with class="parallax-unzoom-grid".
  2. Mark each card with class="parallax-unzoom-card".
  3. Add data-pu-row="0|1|2|..." and data-pu-col="0|1|2|..." per card.
  4. Mark the card that starts at full size with data-pu-focus="true".
  5. Drive --pu-progress 0 → 1 on the .parallax-unzoom-grid from your
     composition's paused GSAP timeline (see example at bottom).

  Tunable CSS variables on .parallax-unzoom-grid:
  - --pu-focus-scale  (default 6)      starting scale of the focus card
  - --pu-sibling-push (default 900px)  outward distance siblings start at
  - --pu-sibling-fade (default 1)      sibling opacity falloff (0–1)
-->

<style>
  .parallax-unzoom-grid {
    --pu-progress: 0;
    --pu-focus-scale: 6;
    --pu-sibling-push: 900px;
    --pu-sibling-fade: 1;
    position: relative;
  }

  .parallax-unzoom-card {
    transform-origin: center center;
    will-change: transform, opacity;
    transform: translate3d(
        calc(var(--pu-dx, 0px) * (1 - var(--pu-progress))),
        calc(var(--pu-dy, 0px) * (1 - var(--pu-progress))),
        0
      )
      scale(calc(0.7 + 0.3 * var(--pu-progress)));
    opacity: calc(var(--pu-progress) * var(--pu-sibling-fade));
  }

  .parallax-unzoom-card[data-pu-focus="true"] {
    z-index: 10;
    transform: translate3d(0, 0, 0)
      scale(calc(var(--pu-focus-scale) - (var(--pu-focus-scale) - 1) * var(--pu-progress)));
    opacity: 1;
  }
</style>

<script>
  (function () {
    const grids = document.querySelectorAll(".parallax-unzoom-grid");

    grids.forEach((grid) => {
      const cards = Array.from(grid.querySelectorAll(".parallax-unzoom-card"));
      if (cards.length === 0) return;

      let focal = cards.find((c) => c.dataset.puFocus === "true");
      if (!focal) {
        focal = cards[Math.floor(cards.length / 2)];
        focal.dataset.puFocus = "true";
      }

      const focusRow = Number(focal.dataset.puRow ?? 0);
      const focusCol = Number(focal.dataset.puCol ?? 0);
      const push = parseFloat(getComputedStyle(grid).getPropertyValue("--pu-sibling-push")) || 900;

      cards.forEach((card) => {
        if (card === focal) return;
        const row = Number(card.dataset.puRow ?? 0);
        const col = Number(card.dataset.puCol ?? 0);
        const dCol = col - focusCol;
        const dRow = row - focusRow;
        const mag = Math.hypot(dCol, dRow) || 1;
        const nx = (dCol / mag) * push * mag;
        const ny = (dRow / mag) * push * mag;
        card.style.setProperty("--pu-dx", `${nx}px`);
        card.style.setProperty("--pu-dy", `${ny}px`);
      });
    });
  })();
</script>

<!--
  Timeline integration example (paste into your composition's GSAP timeline):

  tl.fromTo(
    ".parallax-unzoom-grid",
    { "--pu-progress": 0 },
    {
      "--pu-progress": 1,
      duration: 2.4,
      ease: "power2.inOut",
    },
    startTime, // start time in seconds
  );

  Chaining with parallax-zoom example:
  // Scene 1 (0-3s): zoom IN to the focal card via parallax-zoom
  // Scene 2 (3-6s): unzoom OUT of a NEW grid via parallax-unzoom,
  //                 with the focal card pre-positioned to match scene 1
-->