Soft Blur In

<!--
  Soft Blur In - web-native motion primitive.

  Usage:
  1. Add class="hf-soft-blur-in" to the element you want to reveal.
  2. Paste this style block and script once.
  3. Add the timeline snippet to your paused GSAP timeline.

  Variables. The script reads each one, falls back to the declared default on
  anything missing or unrecognised, and writes the result as a custom property
  on the document root, which every element carrying the class inherits. These
  set where the reveal STARTS: the timeline snippet below still drives offset
  and blur to zero, so each knob decides how far and how hazy the element is
  before it settles, not how long it takes.

    - distance (close | standard | far, default standard): how far the element
      is offset before it slides home, 14px, 28px or 52px.
    - direction (up | down, default up): up starts the element below its
      resting place so it rises in, down starts it above so it drops in.
    - blur (soft | standard | heavy, default standard): the starting blur
      radius, 8px, 18px or 34px, from a light haze to a full smear.

  On every default the result is identical to the original: the element starts
  28px low behind an 18px blur.
-->

<style
  data-composition-variables='[
    { "id": "distance", "type": "enum", "role": "motion", "label": "Distance", "description": "How far the element is offset before it slides home: 14px, 28px or 52px.", "default": "standard", "options": [{ "value": "close", "label": "Close" }, { "value": "standard", "label": "Standard" }, { "value": "far", "label": "Far" }] },
    { "id": "direction", "type": "enum", "role": "motion", "label": "Direction", "description": "up starts the element below its resting place so it rises in, down starts it above so it drops in.", "default": "up", "options": [{ "value": "up", "label": "Up" }, { "value": "down", "label": "Down" }] },
    { "id": "blur", "type": "enum", "role": "style", "label": "Blur", "description": "Starting blur radius, from a light haze to a full smear.", "default": "standard", "options": [{ "value": "soft", "label": "Soft" }, { "value": "standard", "label": "Standard" }, { "value": "heavy", "label": "Heavy" }] }
  ]'
>
  .hf-soft-blur-in {
    opacity: 0;
    transform: translate3d(0, var(--hf-soft-blur-y, 28px), 0);
    filter: blur(var(--hf-soft-blur-radius, 18px));
    will-change: transform, opacity, filter;
  }
</style>

<script>
  (function () {
    "use strict";

    var vars =
      window.__hyperframes && window.__hyperframes.getVariables
        ? window.__hyperframes.getVariables()
        : {};

    // Unrecognised overrides return to their declared defaults.
    function pick(table, value, fallback) {
      return Object.prototype.hasOwnProperty.call(table, value) ? value : fallback;
    }

    var distances = { close: 14, standard: 28, far: 52 };
    var directions = { up: 1, down: -1 };
    var blurs = { soft: 8, standard: 18, heavy: 34 };

    var distance = distances[pick(distances, vars.distance, "standard")];
    var direction = directions[pick(directions, vars.direction, "up")];
    var blur = blurs[pick(blurs, vars.blur, "standard")];

    // Set on the root so every element carrying the class inherits the values,
    // whether it exists yet or not.
    var root = document.documentElement;
    root.style.setProperty("--hf-soft-blur-y", distance * direction + "px");
    root.style.setProperty("--hf-soft-blur-radius", blur + "px");
  })();
</script>

<!--
  Timeline integration:

  tl.to(".hf-soft-blur-in", {
    opacity: 1,
    y: 0,
    filter: "blur(0px)",
    duration: 0.8,
    ease: "power3.out",
    stagger: 0.08,
  }, startTime);
-->