> ## Documentation Index
> Fetch the complete documentation index at: https://hyperframes-fix-nested-composition-media-inpoint.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Rack Focus

> A focus pull with real aperture bokeh: the focal plane travels from a near subject to a far one, so one resolves as the other blows into hard-edged polygon discs that clip to a cat's eye toward the corners. A focus pull only reads against content at two clearly separated depths, so this block carries its own depth-layered night exterior and puts both subject depths on variables.

export const VariablesExplorer = ({previewSrc, compositionId, compositionSrc, variables, children}) => {
  const SHIKI = {
    punct: {
      color: "rgb(31, 35, 40)",
      "--shiki-dark": "#808080"
    },
    tag: {
      color: "rgb(17, 99, 41)",
      "--shiki-dark": "#569CD6"
    },
    attr: {
      color: "rgb(5, 80, 174)",
      "--shiki-dark": "#9CDCFE"
    },
    equals: {
      color: "rgb(31, 35, 40)",
      "--shiki-dark": "#D4D4D4"
    },
    value: {
      color: "rgb(10, 48, 105)",
      "--shiki-dark": "#CE9178"
    }
  };
  const CSS = `
.hf-ve {
  --ve-fg: #18181b;
  --ve-muted: #71717a;
  --ve-line: #e4e4e7;
  --ve-surface: #ffffff;
  --ve-sunken: #fafafa;
  --ve-hover: #f4f4f5;
  --ve-on-bg: #18181b;
  --ve-on-fg: #ffffff;
  --ve-ring: rgba(24, 24, 27, 0.14);
  --ve-danger: #b42318;
}
:where(html.dark) .hf-ve {
  --ve-fg: #f4f4f5;
  --ve-muted: #a1a1aa;
  --ve-line: #27272a;
  --ve-surface: #18181b;
  --ve-sunken: #131316;
  --ve-hover: #27272a;
  --ve-on-bg: #f4f4f5;
  --ve-on-fg: #18181b;
  --ve-ring: rgba(244, 244, 245, 0.2);
  --ve-danger: #ff9d95;
}

.hf-ve-tabs {
  display: inline-flex;
  gap: 2px;
  padding: 3px;
  border: 1px solid var(--ve-line);
  border-radius: 9999px;
  background: var(--ve-sunken);
}
.hf-ve-tab {
  padding: 4px 12px;
  border-radius: 9999px;
  font-size: 12px;
  font-weight: 500;
  color: var(--ve-muted);
  background: transparent;
}
.hf-ve-tab[data-on="true"] {
  color: var(--ve-fg);
  background: var(--ve-surface);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.08);
}
.hf-ve-tab:hover:not([data-on="true"]) { color: var(--ve-fg); }

/* Not a grid. A grid row is as tall as its tallest cell, so a five-line snippet
   sat in the preview's 16:9 box with 300px of dead area under it. The inactive
   pane is taken out of flow instead — and stretches left/right rather than to
   inset 0, so the iframe keeps its own height. An iframe resized on every tab
   switch reflows the composition running inside it. */
.hf-ve-frame { position: relative; }
.hf-ve-cell { min-width: 0; }
.hf-ve-cell[data-on="false"] {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  visibility: hidden;
  pointer-events: none;
}
.hf-ve-preview {
  overflow: hidden;
  border: 1px solid var(--ve-line);
  border-radius: 12px;
}
/* CodeBlock carries the page margins (mt-5 mb-8) that separate it from prose,
   which is dead space inside a tab. Element plus two classes out-specifies a
   Tailwind utility without !important. */
.hf-ve-cell > div.code-block { margin: 0; }
/* The snippet wraps; the source does not.
   A value the reader has to read in full should not hide half of itself off the
   right edge, so the snippet pane wraps — what \`\`\`html wrap does for a fence.
   The width reset is the half that matters: the block's own <code> is sized to
   max-content, and content that never meets an edge never wraps.
   Source is left to scroll sideways like every other code block on the site.
   Wrapping it breaks its indentation, and a comment paragraph re-flowed to a
   narrow column reads worse than one the reader can scroll. */
.hf-ve-snippet .shiki,
.hf-ve-snippet .shiki code {
  white-space: pre-wrap;
  overflow-wrap: anywhere;
}
/* A composition source runs to several hundred lines, and an un-capped tab
   pushes the Customize panel off the screen. The cap goes on the scroll box
   rather than the block, so the filename and its copy button stay put; and it
   is a max-height, so a short source still hugs its own content and the dead
   area under it stays gone. */
.hf-ve-cell .code-block pre {
  max-height: 460px;
  overflow: auto;
}
/* Four classes deep because the rule being answered is three
   (\`html:not(.dark) .codeblock-light pre.shiki code\`), and a shorter selector
   silently loses to it. */
.hf-ve .hf-ve-snippet .code-block pre.shiki code {
  width: auto;
  min-width: 0;
}

.hf-ve-panel {
  margin-top: 12px;
  border: 1px solid var(--ve-line);
  border-radius: 12px;
}
.hf-ve-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 16px;
  border-bottom: 1px solid var(--ve-line);
}
.hf-ve-title {
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ve-muted);
}
.hf-ve-grid {
  display: grid;
  gap: 16px 28px;
  padding: 16px;
}
@media (min-width: 640px) {
  .hf-ve-grid { grid-template-columns: 1fr 1fr; }
}
.hf-ve-row {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 6px;
}
.hf-ve-label { font-size: 14px; font-weight: 500; color: var(--ve-fg); }
.hf-ve-value {
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 12px;
  font-variant-numeric: tabular-nums;
  color: var(--ve-muted);
}
.hf-ve-desc {
  margin: 6px 0 0;
  font-size: 12px;
  line-height: 1.45;
  color: var(--ve-muted);
}

.hf-ve-btn {
  padding: 4px 10px;
  border: 1px solid transparent;
  border-radius: 8px;
  font-size: 12px;
  font-weight: 500;
  color: var(--ve-muted);
  background: transparent;
}
.hf-ve-btn:hover:not(:disabled) { color: var(--ve-fg); background: var(--ve-hover); }
.hf-ve-btn:disabled { opacity: 0.4; cursor: default; }

.hf-ve-field {
  width: 100%;
  height: 36px;
  padding: 0 12px;
  border: 1px solid var(--ve-line);
  border-radius: 8px;
  font-size: 14px;
  line-height: 1.4;
  color: var(--ve-fg);
  background: var(--ve-surface);
}
.hf-ve-field::placeholder { color: var(--ve-muted); }
.hf-ve-mono { font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: 13px; }

/* Focus, once, for every control here. A ring outside the border rather than a
   border colour alone: the border already carries the resting state, so
   recolouring it is a change a reader can miss. Nothing shifts, because the
   ring is a shadow. :focus-visible, so a pointer click does not light it up. */
.hf-ve-field:focus-visible,
.hf-ve-seg-btn:focus-visible,
.hf-ve-tab:focus-visible,
.hf-ve-btn:focus-visible,
.hf-ve-switch:focus-visible,
.hf-ve-swatch:focus-visible {
  outline: none;
  border-color: var(--ve-on-bg);
  box-shadow: 0 0 0 3px var(--ve-ring);
}
/* A range is a track, and ringing the track rings a pill the width of the
   panel. The thumb is the part that has focus, so the thumb is what says so. */
.hf-ve-range:focus-visible { outline: none; }
.hf-ve-range:focus-visible::-webkit-slider-thumb { box-shadow: 0 0 0 4px var(--ve-ring); }
.hf-ve-range:focus-visible::-moz-range-thumb { box-shadow: 0 0 0 4px var(--ve-ring); }
/* Safari still fires :focus for a click on a button, so the pair is kept. */
.hf-ve-field:focus { outline: none; border-color: var(--ve-on-bg); }

/* The enum branch above sends anything past four options here. No shipped item
   does today (every enum in the registry has two to four), so this is styled to
   the point of not looking foreign and no further — the chevron is one neutral
   grey rather than a per-theme pair, because a data URI cannot read a token. */
.hf-ve-select {
  appearance: none;
  -webkit-appearance: none;
  padding-right: 34px;
  background-image: url("data:image/svg+xml;charset=utf-8,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' fill='none' stroke='%2389898f' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpath d='m4 6 4 4 4-4'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 10px center;
  cursor: pointer;
}

.hf-ve-seg {
  display: flex;
  padding: 2px;
  border: 1px solid var(--ve-line);
  border-radius: 8px;
}
.hf-ve-seg-btn {
  flex: 1;
  padding: 4px 8px;
  border-radius: 6px;
  font-size: 12px;
  font-weight: 500;
  color: var(--ve-muted);
  background: transparent;
}
.hf-ve-seg-btn:hover:not([data-on="true"]) { color: var(--ve-fg); background: var(--ve-hover); }
.hf-ve-seg-btn[data-on="true"] { color: var(--ve-on-fg); background: var(--ve-on-bg); }

/* A range, rebuilt. \`accent-color\` alone leaves the platform's hairline track,
   which reads as an unstyled browser part next to everything else here. Each
   engine names its parts differently and shares none of them, so the same
   track and thumb are written twice; a selector either engine cannot parse
   drops the whole rule, which is why they are never grouped. */
.hf-ve-range {
  width: 100%;
  height: 20px;
  appearance: none;
  -webkit-appearance: none;
  border: 0;
  border-radius: 9999px;
  background: transparent;
  cursor: pointer;
}
/* --ve-fill is set per render: painting progress on a native track means a
   two-stop gradient, and only the component knows where the value sits. */
.hf-ve-range::-webkit-slider-runnable-track {
  height: 6px;
  border-radius: 9999px;
  background: linear-gradient(
    to right,
    var(--ve-on-bg) var(--ve-fill, 0%),
    var(--ve-line) var(--ve-fill, 0%)
  );
}
.hf-ve-range::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 16px;
  height: 16px;
  margin-top: -5px;
  border: 2px solid var(--ve-on-bg);
  border-radius: 9999px;
  background: var(--ve-surface);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.14);
}
.hf-ve-range::-moz-range-track { height: 6px; border-radius: 9999px; background: var(--ve-line); }
.hf-ve-range::-moz-range-progress { height: 6px; border-radius: 9999px; background: var(--ve-on-bg); }
.hf-ve-range::-moz-range-thumb {
  width: 16px;
  height: 16px;
  border: 2px solid var(--ve-on-bg);
  border-radius: 9999px;
  background: var(--ve-surface);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.14);
}
/* Hover reads on the part being aimed at rather than on the whole strip: a
   track that darkens under the pointer says "click me and the thumb comes
   here", which is what a native range actually does. */
.hf-ve-range:hover::-webkit-slider-thumb { border-color: var(--ve-fg); }
.hf-ve-range:hover::-moz-range-thumb { border-color: var(--ve-fg); }

/* The number control, and the three things it used to leave unsaid.
 *
 * It could not say where the range ends, so a reader dragging \`stroke_width\`
 * had no idea whether 12 was nearly nothing or nearly everything: the ends now
 * carry min and max.
 *
 * It could not say where the author left the knob, which is the one reference
 * point a panel built around deviating from the author's choice needs: a mark
 * on the track is the default, and a double click puts the value back on it.
 *
 * And it printed the value in the label row, a fixed distance from a thumb that
 * moves, so reading a drag meant looking in two places at once. The value rides
 * the thumb instead.
 *
 * Still a real <input type="range">. Every custom slider on the web reimplements
 * keyboard stepping, touch, and the screen-reader contract, and most of them do
 * one of the three badly; none of what is added here needed the element
 * replaced. Nothing moves that a finger is not moving: the value tracks the
 * pointer because it is the pointer's own readout, and the only transition is
 * the colour one every other control here shares. */
.hf-ve-slider {
  display: grid;
  gap: 1px;
}
.hf-ve-ruler {
  position: relative;
  height: 17px;
  font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
  font-size: 11px;
  font-variant-numeric: tabular-nums;
  line-height: 17px;
  color: var(--ve-muted);
}
.hf-ve-bound {
  position: absolute;
  top: 0;
}
.hf-ve-bound[data-end="min"] { left: 0; }
.hf-ve-bound[data-end="max"] { right: 0; }
/* An end steps aside rather than being overprinted by the value arriving on
   top of it. Visibility, not opacity: there is no fade here, the label is
   either the thing being read or it is out of the way. */
.hf-ve-ruler[data-near="min"] .hf-ve-bound[data-end="min"],
.hf-ve-ruler[data-near="max"] .hf-ve-bound[data-end="max"] {
  visibility: hidden;
}
/* translateX is centring, not motion: the readout is as wide as its own digits
   and has to hang half of that either side of the thumb. */
.hf-ve-readout {
  position: absolute;
  top: 0;
  left: calc(var(--ve-fill, 0%) + var(--ve-fill-nudge, 0px));
  transform: translateX(-50%);
  color: var(--ve-fg);
  font-weight: 600;
  white-space: nowrap;
}
.hf-ve-track {
  position: relative;
  display: block;
}
.hf-ve-range { display: block; }
.hf-ve-default {
  position: absolute;
  top: 5px;
  left: calc(var(--ve-default, 50%) + var(--ve-default-nudge, 0px));
  width: 2px;
  height: 10px;
  margin-left: -1px;
  border-radius: 1px;
  background: var(--ve-muted);
  pointer-events: none;
}

/* A switch, for the boolean type. It used to fall through to the text input at
   the end of control(), which asked the reader to type the word "true". */
.hf-ve-switch {
  display: inline-flex;
  align-items: center;
  width: 40px;
  height: 24px;
  padding: 2px;
  border: 1px solid var(--ve-line);
  border-radius: 9999px;
  background: var(--ve-sunken);
  cursor: pointer;
}
.hf-ve-switch[data-on="true"] { border-color: var(--ve-on-bg); background: var(--ve-on-bg); }
.hf-ve-switch-dot {
  width: 18px;
  height: 18px;
  border-radius: 9999px;
  background: var(--ve-surface);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.18);
}
.hf-ve-switch[data-on="true"] .hf-ve-switch-dot {
  background: var(--ve-on-fg);
  transform: translateX(16px);
}

/* The SVG import control: the same text field, with a way to fill it.
 *
 * The whole block is the drop target, not just the field, so a file let go over
 * the button lands too. It says so by taking the same border colour a focused
 * field takes, which is the one feedback channel this panel has left.
 *
 * A bare <input type="file"> is unlabelled, unstyleable and reads as "No file
 * chosen" next to controls that carry their own value, so the real input is
 * taken out of the layout and the tab order and a button in front of it is what
 * a reader sees and what a keyboard reaches. Hidden with size and opacity
 * rather than display:none, because an input that is not rendered at all is one
 * some browsers decline to open a picker for. */
.hf-ve-drop {
  display: grid;
  gap: 8px;
}
.hf-ve-drop[data-over="true"] .hf-ve-dropzone {
  border-color: var(--ve-on-bg);
  border-style: solid;
}

/* The import is the action almost everyone wants: a reader arrives with a
   shape, not with path data. A dashed target reads as "put a file here" on
   sight, where a button beneath a field of coordinates read as an afterthought
   to the coordinates. */
.hf-ve-dropzone {
  display: grid;
  justify-items: center;
  gap: 6px;
  padding: 18px 12px;
  border: 1px dashed var(--ve-line);
  border-radius: 10px;
  background: var(--ve-surface);
  text-align: center;
}
.hf-ve-dropzone .hf-ve-btn {
  padding: 7px 16px;
  font-size: 13px;
  color: var(--ve-fg);
  border-color: var(--ve-line);
  background: var(--ve-bg);
}
.hf-ve-dropzone .hf-ve-btn:hover:not(:disabled) { background: var(--ve-hover); }

/* Path data stays reachable, but a reader has to ask for it. A native details
   element rather than our own toggle, so it opens with the keyboard and is
   announced as expandable without any wiring. */
.hf-ve-advanced > summary {
  font-size: 12px;
  color: var(--ve-muted);
  cursor: pointer;
  list-style: none;
  padding: 2px 0;
}
.hf-ve-advanced > summary::-webkit-details-marker { display: none; }
.hf-ve-advanced > summary::before { content: "▸ "; }
.hf-ve-advanced[open] > summary::before { content: "▾ "; }
.hf-ve-advanced > summary:hover { color: var(--ve-fg); }
.hf-ve-advanced .hf-ve-field { margin-top: 6px; }
.hf-ve-file {
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
  pointer-events: none;
}
.hf-ve-note {
  margin: 0;
  min-width: 0;
  font-size: 12px;
  line-height: 1.4;
  color: var(--ve-muted);
}
.hf-ve-note[data-tone="error"] { color: var(--ve-danger); }
.hf-ve-note[data-tone="ok"] { color: var(--ve-fg); }

.hf-ve-swatch {
  width: 40px;
  height: 32px;
  flex-shrink: 0;
  padding: 2px;
  border: 1px solid var(--ve-line);
  border-radius: 8px;
  background: var(--ve-surface);
  cursor: pointer;
}

/* Nothing here moves.
 *
 * A press-down scale on every button and field, a scale-in on the tab panes, a
 * springing switch knob and a growing slider thumb were all flourish: the
 * control had already told you what it did by changing colour, and the motion
 * was a second, slower answer to a question already settled. What is left is
 * one colour transition, short enough to read as immediate and long enough not
 * to flicker. A control here may change colour; it does not move.
 *
 * Which is also why there is no prefers-reduced-motion block any more. There is
 * no motion left to reduce. */
.hf-ve-tint {
  transition:
    background-color 100ms ease,
    border-color 100ms ease,
    color 100ms ease;
}
`;
  const isSvgPathData = value => typeof value === "string" && (/^\s*[Mm]\s*-?[\d.]/).test(value);
  const parsePathData = d => {
    const source = String(d);
    const arity = {
      M: 2,
      L: 2,
      H: 1,
      V: 1,
      C: 6,
      S: 4,
      Q: 4,
      T: 2,
      A: 7,
      Z: 0
    };
    const commands = [];
    let at = 0;
    let code = "";
    const separator = () => {
      while (at < source.length && (/[\s,]/).test(source[at])) at += 1;
    };
    const digits = () => {
      while (at < source.length && source[at] >= "0" && source[at] <= "9") at += 1;
    };
    const number = () => {
      separator();
      const start = at;
      if (source[at] === "+" || source[at] === "-") at += 1;
      digits();
      if (source[at] === ".") {
        at += 1;
        digits();
      }
      if (source[at] === "e" || source[at] === "E") {
        at += 1;
        if (source[at] === "+" || source[at] === "-") at += 1;
        digits();
      }
      const text = source.slice(start, at);
      const value = Number(text);
      if (text === "" || !Number.isFinite(value)) {
        throw new Error(`expected a number at character ${start + 1}`);
      }
      return value;
    };
    const flag = () => {
      separator();
      const character = source[at];
      if (character !== "0" && character !== "1") {
        throw new Error(`expected an arc flag at character ${at + 1}`);
      }
      at += 1;
      return Number(character);
    };
    separator();
    while (at < source.length) {
      const character = source[at];
      if ((/[a-zA-Z]/).test(character)) {
        if (arity[character.toUpperCase()] === undefined) {
          throw new Error(`unknown command "${character}"`);
        }
        code = character;
        at += 1;
      } else if (code === "") {
        throw new Error("path data must open with a command");
      } else if (code === "M" || code === "m") {
        code = code === "M" ? "L" : "l";
      } else if (code === "Z" || code === "z") {
        throw new Error(`expected a command at character ${at + 1}`);
      }
      const letter = code.toUpperCase();
      const args = [];
      if (letter === "A") {
        args.push(number(), number(), number(), flag(), flag(), number(), number());
      } else {
        for (let taken = 0; taken < arity[letter]; taken += 1) args.push(number());
      }
      commands.push({
        code,
        args
      });
      separator();
    }
    if (commands.length === 0) throw new Error("path data is empty");
    return commands;
  };
  const normalisePathData = commands => {
    const out = [];
    let x = 0;
    let y = 0;
    let startX = 0;
    let startY = 0;
    let cubicControl = null;
    let quadraticControl = null;
    for (const {code, args} of commands) {
      const letter = code.toUpperCase();
      const relative = code !== letter;
      const dx = relative ? x : 0;
      const dy = relative ? y : 0;
      const pairs = values => {
        const mapped = [];
        for (let index = 0; index + 1 < values.length; index += 2) {
          mapped.push(values[index] + dx, values[index + 1] + dy);
        }
        return mapped;
      };
      let nextCubic = null;
      let nextQuadratic = null;
      if (letter === "M") {
        const [px, py] = pairs(args);
        out.push({
          code: "M",
          args: [px, py]
        });
        x = px;
        y = py;
        startX = px;
        startY = py;
      } else if (letter === "L") {
        const [px, py] = pairs(args);
        out.push({
          code: "L",
          args: [px, py]
        });
        x = px;
        y = py;
      } else if (letter === "H") {
        x = args[0] + dx;
        out.push({
          code: "L",
          args: [x, y]
        });
      } else if (letter === "V") {
        y = args[0] + dy;
        out.push({
          code: "L",
          args: [x, y]
        });
      } else if (letter === "C") {
        const points = pairs(args);
        out.push({
          code: "C",
          args: points
        });
        nextCubic = [points[2], points[3]];
        x = points[4];
        y = points[5];
      } else if (letter === "S") {
        const points = pairs(args);
        const first = cubicControl ? [2 * x - cubicControl[0], 2 * y - cubicControl[1]] : [x, y];
        out.push({
          code: "C",
          args: [...first, ...points]
        });
        nextCubic = [points[0], points[1]];
        x = points[2];
        y = points[3];
      } else if (letter === "Q") {
        const points = pairs(args);
        out.push({
          code: "Q",
          args: points
        });
        nextQuadratic = [points[0], points[1]];
        x = points[2];
        y = points[3];
      } else if (letter === "T") {
        const points = pairs(args);
        const control = quadraticControl ? [2 * x - quadraticControl[0], 2 * y - quadraticControl[1]] : [x, y];
        out.push({
          code: "Q",
          args: [...control, ...points]
        });
        nextQuadratic = control;
        x = points[0];
        y = points[1];
      } else if (letter === "A") {
        const endX = args[5] + dx;
        const endY = args[6] + dy;
        out.push(...arcToCubics(x, y, args[0], args[1], args[2], args[3], args[4], endX, endY));
        x = endX;
        y = endY;
      } else if (letter === "Z") {
        out.push({
          code: "Z",
          args: []
        });
        x = startX;
        y = startY;
      }
      cubicControl = nextCubic;
      quadraticControl = nextQuadratic;
    }
    return out;
  };
  const arcToCubics = (x1, y1, rx, ry, rotation, largeArc, sweep, x2, y2) => {
    if (x1 === x2 && y1 === y2) return [];
    let radiusX = Math.abs(rx);
    let radiusY = Math.abs(ry);
    if (radiusX === 0 || radiusY === 0) return [{
      code: "L",
      args: [x2, y2]
    }];
    const phi = rotation * Math.PI / 180;
    const cosPhi = Math.cos(phi);
    const sinPhi = Math.sin(phi);
    const midX = (x1 - x2) / 2;
    const midY = (y1 - y2) / 2;
    const primeX = cosPhi * midX + sinPhi * midY;
    const primeY = -sinPhi * midX + cosPhi * midY;
    const oversize = primeX * primeX / (radiusX * radiusX) + primeY * primeY / (radiusY * radiusY);
    if (oversize > 1) {
      const grow = Math.sqrt(oversize);
      radiusX *= grow;
      radiusY *= grow;
    }
    const denominator = radiusX * radiusX * primeY * primeY + radiusY * radiusY * primeX * primeX;
    const numerator = radiusX * radiusX * radiusY * radiusY - radiusX * radiusX * primeY * primeY - radiusY * radiusY * primeX * primeX;
    const factor = (largeArc === sweep ? -1 : 1) * Math.sqrt(Math.max(0, numerator) / denominator);
    const centrePrimeX = factor * radiusX * primeY / radiusY;
    const centrePrimeY = -factor * radiusY * primeX / radiusX;
    const centreX = cosPhi * centrePrimeX - sinPhi * centrePrimeY + (x1 + x2) / 2;
    const centreY = sinPhi * centrePrimeX + cosPhi * centrePrimeY + (y1 + y2) / 2;
    const angle = (ux, uy, vx, vy) => {
      const length = Math.hypot(ux, uy) * Math.hypot(vx, vy);
      const cosine = length === 0 ? 1 : Math.min(1, Math.max(-1, (ux * vx + uy * vy) / length));
      return (ux * vy - uy * vx < 0 ? -1 : 1) * Math.acos(cosine);
    };
    const fromX = (primeX - centrePrimeX) / radiusX;
    const fromY = (primeY - centrePrimeY) / radiusY;
    const toX = (-primeX - centrePrimeX) / radiusX;
    const toY = (-primeY - centrePrimeY) / radiusY;
    const start = angle(1, 0, fromX, fromY);
    let sweptAngle = angle(fromX, fromY, toX, toY);
    if (!sweep && sweptAngle > 0) sweptAngle -= 2 * Math.PI;
    if (sweep && sweptAngle < 0) sweptAngle += 2 * Math.PI;
    const steps = Math.max(1, Math.ceil(Math.abs(sweptAngle) / (Math.PI / 2)));
    const step = sweptAngle / steps;
    const handle = 4 / 3 * Math.tan(step / 4);
    const at = t => [centreX + radiusX * Math.cos(t) * cosPhi - radiusY * Math.sin(t) * sinPhi, centreY + radiusX * Math.cos(t) * sinPhi + radiusY * Math.sin(t) * cosPhi];
    const slope = t => [-radiusX * Math.sin(t) * cosPhi - radiusY * Math.cos(t) * sinPhi, -radiusX * Math.sin(t) * sinPhi + radiusY * Math.cos(t) * cosPhi];
    const out = [];
    for (let index = 0; index < steps; index += 1) {
      const from = start + index * step;
      const to = from + step;
      const [ax, ay] = at(from);
      const [bx, by] = at(to);
      const [aSlopeX, aSlopeY] = slope(from);
      const [bSlopeX, bSlopeY] = slope(to);
      out.push({
        code: "C",
        args: [ax + handle * aSlopeX, ay + handle * aSlopeY, bx - handle * bSlopeX, by - handle * bSlopeY, bx, by]
      });
    }
    const last = out[out.length - 1];
    last.args[4] = x2;
    last.args[5] = y2;
    return out;
  };
  const transformPathData = (segments, matrix) => segments.map(({code, args}) => {
    const moved = [];
    for (let index = 0; index + 1 < args.length; index += 2) {
      const x = args[index];
      const y = args[index + 1];
      moved.push(matrix.a * x + matrix.c * y + matrix.e, matrix.b * x + matrix.d * y + matrix.f);
    }
    return {
      code,
      args: moved
    };
  });
  const fitMatrix = (source, target) => {
    const chosen = Math.min(target.width / source.width, target.height / source.height);
    const scale = Number.isFinite(chosen) && chosen > 0 ? chosen : 1;
    return {
      a: scale,
      b: 0,
      c: 0,
      d: scale,
      e: target.x + target.width / 2 - (source.x + source.width / 2) * scale,
      f: target.y + target.height / 2 - (source.y + source.height / 2) * scale
    };
  };
  const printPathData = segments => segments.map(({code, args}) => {
    if (args.length === 0) return code;
    const numbers = args.map(value => {
      const rounded = Math.round(value * 100) / 100;
      return String(Object.is(rounded, -0) ? 0 : rounded);
    });
    return `${code} ${numbers.join(" ")}`;
  }).join(" ");
  const shapePathData = (tag, attrs) => {
    const number = (name, fallback = 0) => {
      const value = parseFloat(attrs[name]);
      return Number.isFinite(value) ? value : fallback;
    };
    if (tag === "path") {
      const d = typeof attrs.d === "string" ? attrs.d.trim() : "";
      return d === "" ? null : d;
    }
    if (tag === "rect") {
      const width = number("width");
      const height = number("height");
      if (!(width > 0) || !(height > 0)) return null;
      const x = number("x");
      const y = number("y");
      const declaredX = parseFloat(attrs.rx);
      const declaredY = parseFloat(attrs.ry);
      const rawX = Number.isFinite(declaredX) ? declaredX : declaredY;
      const rawY = Number.isFinite(declaredY) ? declaredY : declaredX;
      const rx = Math.min(Math.max(Number.isFinite(rawX) ? rawX : 0, 0), width / 2);
      const ry = Math.min(Math.max(Number.isFinite(rawY) ? rawY : 0, 0), height / 2);
      if (rx === 0 || ry === 0) {
        return `M ${x} ${y} H ${x + width} V ${y + height} H ${x} Z`;
      }
      return [`M ${x + rx} ${y}`, `H ${x + width - rx}`, `A ${rx} ${ry} 0 0 1 ${x + width} ${y + ry}`, `V ${y + height - ry}`, `A ${rx} ${ry} 0 0 1 ${x + width - rx} ${y + height}`, `H ${x + rx}`, `A ${rx} ${ry} 0 0 1 ${x} ${y + height - ry}`, `V ${y + ry}`, `A ${rx} ${ry} 0 0 1 ${x + rx} ${y}`, "Z"].join(" ");
    }
    if (tag === "circle" || tag === "ellipse") {
      const rx = tag === "circle" ? number("r") : number("rx");
      const ry = tag === "circle" ? number("r") : number("ry");
      if (!(rx > 0) || !(ry > 0)) return null;
      const cx = number("cx");
      const cy = number("cy");
      return [`M ${cx - rx} ${cy}`, `A ${rx} ${ry} 0 1 0 ${cx + rx} ${cy}`, `A ${rx} ${ry} 0 1 0 ${cx - rx} ${cy}`, "Z"].join(" ");
    }
    if (tag === "line") {
      const x1 = number("x1");
      const y1 = number("y1");
      const x2 = number("x2");
      const y2 = number("y2");
      if (x1 === x2 && y1 === y2) return null;
      return `M ${x1} ${y1} L ${x2} ${y2}`;
    }
    if (tag === "polyline" || tag === "polygon") {
      const values = String(attrs.points ?? "").trim().split(/[\s,]+/).map(Number).filter(value => Number.isFinite(value));
      if (values.length < 4) return null;
      const steps = [`M ${values[0]} ${values[1]}`];
      for (let index = 2; index + 1 < values.length; index += 2) {
        steps.push(`L ${values[index]} ${values[index + 1]}`);
      }
      if (tag === "polygon") steps.push("Z");
      return steps.join(" ");
    }
    return null;
  };
  const svgToPathData = (svgText, targetPathData, doc = document) => {
    const NS = "http://www.w3.org/2000/svg";
    const parsed = new DOMParser().parseFromString(String(svgText), "image/svg+xml");
    if (parsed.getElementsByTagName("parsererror").length > 0 || !parsed.documentElement || parsed.documentElement.localName !== "svg") {
      throw new Error("That file is not an SVG, or its markup is malformed.");
    }
    const host = doc.createElement("div");
    host.setAttribute("aria-hidden", "true");
    host.style.cssText = "position:fixed;left:-99999px;top:0;width:600px;height:600px;overflow:hidden;";
    const svg = doc.importNode(parsed.documentElement, true);
    host.appendChild(svg);
    doc.body.appendChild(host);
    try {
      const reference = doc.createElementNS(NS, "g");
      svg.appendChild(reference);
      const rootMatrix = reference.getScreenCTM();
      const defining = ["defs", "clipPath", "mask", "symbol", "marker", "pattern"];
      const isDefinition = element => {
        for (let node = element.parentNode; node && node !== svg; node = node.parentNode) {
          if (defining.includes(node.localName)) return true;
        }
        return false;
      };
      const shapes = [...svg.querySelectorAll("path,rect,circle,ellipse,line,polyline,polygon")];
      const segments = [];
      let shapesUsed = 0;
      let firstProblem = null;
      for (const element of shapes) {
        if (isDefinition(element)) continue;
        if (doc.defaultView.getComputedStyle(element).display === "none") continue;
        const attrs = {};
        for (const attribute of element.attributes) attrs[attribute.localName] = attribute.value;
        const d = shapePathData(element.localName, attrs);
        if (d === null) continue;
        let own;
        try {
          own = normalisePathData(parsePathData(d));
        } catch (error) {
          firstProblem = firstProblem ?? error.message;
          continue;
        }
        const matrix = element.getScreenCTM();
        segments.push(...rootMatrix && matrix ? transformPathData(own, rootMatrix.inverse().multiply(matrix)) : own);
        shapesUsed += 1;
      }
      if (segments.length === 0) {
        if (firstProblem) throw new Error(`This SVG has unreadable path data: ${firstProblem}.`);
        const untraceable = ["text", "image", "use"].find(tag => svg.getElementsByTagName(tag).length > 0);
        throw new Error(untraceable ? `This SVG draws with <${untraceable}>, which has no outline to trace. Convert it to paths and try again.` : "This SVG has no shapes to import.");
      }
      const probe = doc.createElementNS(NS, "path");
      svg.appendChild(probe);
      probe.setAttribute("d", printPathData(segments));
      const source = probe.getBBox();
      if (!(source.width > 0) || !(source.height > 0)) {
        if (!(source.width > 0) && !(source.height > 0)) {
          throw new Error("This SVG's shapes have no size.");
        }
      }
      probe.setAttribute("d", String(targetPathData));
      const target = probe.getBBox();
      return {
        d: printPathData(transformPathData(segments, fitMatrix(source, target))),
        shapes: shapesUsed
      };
    } finally {
      host.remove();
    }
  };
  const granularity = value => {
    const decimals = String(value).split(".")[1];
    return decimals ? Number(`1e-${decimals.length}`) : 1;
  };
  const readout = (variable, value) => {
    if (variable.type === "number") return "";
    if (variable.type === "color") return String(value);
    if (variable.type === "enum") {
      const hit = (variable.options ?? []).find(o => o.value === value);
      return hit ? hit.label ?? hit.value : String(value);
    }
    return "";
  };
  const control = (variable, value, onChange, note, onNote, onTyping) => {
    const options = variable.options ?? [];
    if (variable.type === "enum" && options.length > 0 && options.length <= 4) {
      return <div className="hf-ve-seg">
          {options.map(o => <button key={o.value} type="button" data-on={value === o.value} aria-pressed={value === o.value} onClick={() => onChange(o.value)} className="hf-ve-seg-btn hf-ve-tint">
              {o.label ?? o.value}
            </button>)}
        </div>;
    }
    if (variable.type === "enum") {
      return <select className="hf-ve-field hf-ve-select hf-ve-tint" value={value} aria-label={variable.label ?? variable.id} onChange={e => onChange(e.target.value)}>
          {options.map(o => <option key={o.value} value={o.value}>
              {o.label ?? o.value}
            </option>)}
        </select>;
    }
    if (variable.type === "number") {
      const min = Number(variable.min);
      const max = Number(variable.max);
      const unit = variable.unit ?? "";
      const declaredStep = Number(variable.step);
      const step = declaredStep > 0 ? declaredStep : 1;
      const label = variable.label ?? variable.id;
      if (!(Number.isFinite(min) && Number.isFinite(max) && max > min)) {
        return <input type="number" className="hf-ve-field hf-ve-mono hf-ve-tint" value={value} min={Number.isFinite(min) ? min : undefined} max={Number.isFinite(max) ? max : undefined} step={declaredStep > 0 ? declaredStep : granularity(variable.default)} aria-label={label} onChange={e => {
          const next = Number(e.target.value);
          if (e.target.value !== "" && Number.isFinite(next)) onChange(next);
        }} />;
      }
      const at = n => Math.min(1, Math.max(0, (Number(n) - min) / (max - min)));
      const now = at(value);
      const authored = at(variable.default);
      const place = fraction => ({
        offset: `${fraction * 100}%`,
        nudge: `${(0.5 - fraction) * 16}px`
      });
      const value_ = place(now);
      const default_ = place(authored);
      const grain = event => {
        event.currentTarget.step = event.shiftKey ? step / 10 : step;
      };
      return <div className="hf-ve-slider" style={{
        "--ve-fill": value_.offset,
        "--ve-fill-nudge": value_.nudge,
        "--ve-default": default_.offset,
        "--ve-default-nudge": default_.nudge
      }}>
          {}
          <div className="hf-ve-ruler" data-near={now < 0.14 ? "min" : now > 0.86 ? "max" : ""} aria-hidden="true">
            <span className="hf-ve-bound" data-end="min">
              {min}
            </span>
            <span className="hf-ve-bound" data-end="max">
              {max}
            </span>
            <span className="hf-ve-readout">
              {value}
              {unit}
            </span>
          </div>
          <span className="hf-ve-track">
            <input type="range" className="hf-ve-range" min={min} max={max} step={step} value={value} aria-label={label} aria-valuetext={`${value}${unit}`} onChange={e => onChange(Number(e.target.value))} onPointerDown={grain} onKeyDown={grain} onDoubleClick={() => onChange(variable.default)} />
            {}
            {Math.abs(now - authored) > 0.04 && <span className="hf-ve-default" aria-hidden="true" />}
          </span>
        </div>;
    }
    if (variable.type === "boolean") {
      const on = value === true || value === "true";
      return <button type="button" role="switch" aria-checked={on} aria-label={variable.label ?? variable.id} data-on={on} onClick={() => onChange(!on)} className="hf-ve-switch">
          <span className="hf-ve-switch-dot" />
        </button>;
    }
    if (variable.type === "color") {
      return <div className="flex items-center gap-2">
          <input type="color" className="hf-ve-swatch hf-ve-tint" value={value} aria-label={variable.label ?? variable.id} onChange={e => onChange(e.target.value)} />
          <input type="text" className="hf-ve-field hf-ve-mono hf-ve-tint" value={value} onChange={e => onChange(e.target.value)} onFocus={() => onTyping(variable.id)} onBlur={() => onTyping(null)} onKeyDown={e => {
        if (e.key === "Enter") e.currentTarget.blur();
      }} />
        </div>;
    }
    if (isSvgPathData(variable.default)) {
      const fileId = `hf-ve-file-${variable.id}`;
      const noteId = `hf-ve-note-${variable.id}`;
      const receive = file => {
        if (!file) return;
        file.text().then(text => {
          const {d, shapes} = svgToPathData(text, variable.default);
          onChange(d);
          onNote({
            tone: "ok",
            message: `${file.name}: ${shapes} shape${shapes === 1 ? "" : "s"} scaled to fit.`
          });
        }).catch(error => onNote({
          tone: "error",
          message: error.message
        }));
      };
      return <div className="hf-ve-drop" onDragOver={event => {
        event.preventDefault();
        event.currentTarget.dataset.over = "true";
      }} onDragLeave={event => {
        event.currentTarget.dataset.over = "false";
      }} onDrop={event => {
        event.preventDefault();
        event.currentTarget.dataset.over = "false";
        receive(event.dataTransfer.files[0]);
      }}>
          {}
          <div className="hf-ve-dropzone">
            <button type="button" className="hf-ve-btn hf-ve-tint" onClick={() => document.getElementById(fileId).click()}>
              Import SVG
            </button>
            <input id={fileId} type="file" accept=".svg,image/svg+xml" className="hf-ve-file" tabIndex={-1} aria-hidden="true" onChange={event => {
        receive(event.target.files[0]);
        event.target.value = "";
      }} />
            {}
            <p id={noteId} role="status" className="hf-ve-note" data-tone={note ? note.tone : ""}>
              {note ? note.message : "Or drop one here. Scaled to fit and centred."}
            </p>
          </div>
          <details className="hf-ve-advanced">
            <summary>Path data</summary>
            <input type="text" className="hf-ve-field hf-ve-mono hf-ve-tint" value={value} aria-label={variable.label ?? variable.id} onChange={e => onChange(e.target.value)} onFocus={() => onTyping(variable.id)} onBlur={() => onTyping(null)} onKeyDown={e => {
        if (e.key === "Enter") e.currentTarget.blur();
      }} />
          </details>
        </div>;
    }
    return <input type="text" className="hf-ve-field hf-ve-tint" value={value} aria-label={variable.label ?? variable.id} onChange={e => onChange(e.target.value)} onFocus={() => onTyping(variable.id)} onBlur={() => onTyping(null)} onKeyDown={e => {
      if (e.key === "Enter") e.currentTarget.blur();
    }} />;
  };
  const variablesKey = JSON.stringify(variables);
  const defaults = useMemo(() => {
    const built = {};
    for (const v of variables) if (v.default !== undefined) built[v.id] = v.default;
    return built;
  }, [variablesKey]);
  const urlKey = `vars-${compositionId}`;
  const readFromUrl = () => {
    if (typeof window === "undefined") return {};
    try {
      const raw = new URLSearchParams(window.location.search).get(urlKey);
      if (!raw) return {};
      const parsed = JSON.parse(raw);
      if (!parsed || typeof parsed !== "object" || Array.isArray(parsed)) return {};
      const declared = new Set(variables.map(v => v.id));
      return Object.fromEntries(Object.entries(parsed).filter(([id]) => declared.has(id)));
    } catch {
      return {};
    }
  };
  const [values, setValues] = useState(() => ({
    ...defaults,
    ...readFromUrl()
  }));
  useEffect(() => {
    const fromUrl = readFromUrl();
    if (Object.keys(fromUrl).length > 0) setValues(current => ({
      ...current,
      ...fromUrl
    }));
  }, []);
  useEffect(() => {
    if (typeof window === "undefined") return;
    const changed = Object.fromEntries(Object.entries(values).filter(([id, value]) => JSON.stringify(value) !== JSON.stringify(defaults[id])));
    const url = new URL(window.location.href);
    if (Object.keys(changed).length === 0) url.searchParams.delete(urlKey); else url.searchParams.set(urlKey, JSON.stringify(changed));
    const next = url.toString();
    if (next !== window.location.href) {
      window.history.replaceState(null, "", next);
      window.dispatchEvent(new CustomEvent("hf-vars-changed"));
    }
  }, [values, defaults, urlKey]);
  const [notes, setNotes] = useState({});
  const [typing, setTyping] = useState(null);
  const posted = useRef(null);
  const [tab, setTab] = useState("preview");
  const frame = useRef(null);
  const bootstrap = ["<!doctype html><html><head><meta charset='utf-8'>", "<style>html,body{margin:0;height:100%;overflow:hidden;background:transparent}", "hyperframes-player{display:block;width:100%;height:100%}</style>", '<script src="https://cdn.jsdelivr.net/npm/@hyperframes/player@0.7/dist/hyperframes-player.global.js"></' + "script>", "</head><body><script>", "(function(){", `  var PAYLOAD = ${JSON.stringify(previewSrc)};`, `  var INITIAL = ${JSON.stringify({
    ...defaults,
    ...readFromUrl()
  })};`, "  var html = null, player = null, poll = null;", "  function withValues(source, values) {", "    var json = JSON.stringify(values);", "    var attr = json.replace(/'/g, '&#39;');", "    var out = source.replace(/\\sdata-variable-values=(?:\"[^\"]*\"|'[^']*')/gi, '');", "    out = out.replace(/(data-composition-src=)/gi, \"data-variable-values='\" + attr + \"' $1\");", "    var tag = '<' + 'script>window.__hfVariables=' + json + ';<' + '/script>';", "    return /<head[^>]*>/i.test(out)", "      ? out.replace(/<head([^>]*)>/i, '<head$1>' + tag)", "      : tag + out;", "  }", "  function arm(resumeAt) {", "    clearInterval(poll);", "    var last = -1, tries = 0, seeked = false;", "    poll = setInterval(function () {", "      if (player.ready) {", "        if (!seeked) { seeked = true; if (resumeAt > 0) player.seek(resumeAt); }", "        player.play();", "      }", "      if (seeked && player.currentTime > 0 && player.currentTime !== last) {", "        clearInterval(poll); return;", "      }", "      last = player.currentTime;", "      if (++tries > 150) clearInterval(poll);", "    }, 100);", "  }", "  function mount(values, resumeAt) {", "    if (html === null) return;", "    player.setAttribute('srcdoc', withValues(html, values));", "    arm(resumeAt || 0);", "  }", "  player = document.createElement('hyperframes-player');", "  player.setAttribute('controls', ''); player.setAttribute('muted', '');", "  document.body.appendChild(player);", "  player.addEventListener('ended', function () { player.seek(0); player.play(); });", "  fetch(PAYLOAD).then(function (r) { return r.json(); }).then(function (d) {", "    html = d.html; mount(INITIAL, 0);", "  }).catch(function (e) {", "    document.body.innerHTML = '<pre style=\"color:#f66;font:12px monospace;padding:12px\">preview unavailable: ' + e + '</pre>';", "  });", "  addEventListener('message', function (event) {", "    var values = event.data && event.data.hfVariables;", "    if (!values) return;", "    mount(values, player.currentTime || 0);", "  });", "})();", "</" + "script></body></html>"].join("");
  useEffect(() => {
    if (typing !== null) return;
    const payload = JSON.stringify(values);
    if (payload === posted.current) return;
    const timer = setTimeout(() => {
      const target = frame.current && frame.current.contentWindow;
      if (!target) return;
      posted.current = payload;
      target.postMessage({
        hfVariables: values
      }, window.location.origin);
    }, 150);
    return () => clearTimeout(timer);
  }, [values, typing]);
  const printed = JSON.stringify(values, null, 2).split("\n").join("\n  ");
  const attributes = [["data-composition-id", `"${compositionId}"`], ["data-composition-src", `"${compositionSrc}"`], ["data-variable-values", `'${printed}'`]];
  const snippetLines = [[[SHIKI.punct, "<"], [SHIKI.tag, "div"]]];
  for (const [name, literal] of attributes) {
    const [head, ...rest] = literal.split("\n");
    snippetLines.push([[SHIKI.attr, `  ${name}`], [SHIKI.equals, "="], [SHIKI.value, head]]);
    for (const line of rest) snippetLines.push([[SHIKI.value, line]]);
  }
  snippetLines.push([[SHIKI.punct, "></"], [SHIKI.tag, "div"], [SHIKI.punct, ">"]]);
  const dirty = variables.some(v => values[v.id] !== defaults[v.id]);
  const installCommand = (() => {
    const base = `npx hyperframes add ${compositionId}`;
    if (!dirty) return base;
    const changed = {};
    for (const v of variables) {
      if (JSON.stringify(values[v.id]) !== JSON.stringify(defaults[v.id])) changed[v.id] = values[v.id];
    }
    return `${base} --vars '${JSON.stringify(changed)}'`;
  })();
  const TABS = [["preview", "Preview"], ...children ? [["code", "Code"]] : [], ["snippet", "Snippet"]];
  return <div className="hf-ve not-prose my-4">
      <style dangerouslySetInnerHTML={{
    __html: CSS
  }} />

      <div className="mb-3 flex items-center gap-3">
        <div className="hf-ve-tabs">
          {TABS.map(([id, label]) => <button key={id} type="button" data-on={tab === id} aria-pressed={tab === id} onClick={() => setTab(id)} className="hf-ve-tab hf-ve-tint">
              {label}
            </button>)}
        </div>
      </div>

      {}
      <div className="hf-ve-frame">
        <div className="hf-ve-cell" data-on={tab === "preview"}>
          <iframe ref={frame} srcDoc={bootstrap} className="hf-ve-preview block aspect-video w-full" title={`${compositionId} preview`} />
        </div>
        {children && <div className="hf-ve-cell" data-on={tab === "code"}>
            {children}
          </div>}
        <div className="hf-ve-cell hf-ve-snippet" data-on={tab === "snippet"}>
          {}
          <CodeBlock filename="Terminal">
            <pre className="shiki shiki-themes github-light-default dark-plus" style={{
    backgroundColor: "rgb(255, 255, 255)",
    "--shiki-dark-bg": "#0B0C0E",
    color: "rgb(31, 35, 40)",
    "--shiki-dark": "#D4D4D4"
  }}>
              <code>
                <span className="line">
                  <span style={SHIKI.value}>{installCommand}</span>
                  {"\n"}
                </span>
              </code>
            </pre>
          </CodeBlock>
          {}
          <CodeBlock filename="index.html">
            <pre className="shiki shiki-themes github-light-default dark-plus" style={{
    backgroundColor: "rgb(255, 255, 255)",
    "--shiki-dark-bg": "#0B0C0E",
    color: "rgb(31, 35, 40)",
    "--shiki-dark": "#D4D4D4"
  }}>
              <code>
                {snippetLines.map((tokens, line) => <span key={line} className="line">
                    {tokens.map(([style, text], token) => <span key={token} style={style}>
                        {text}
                      </span>)}
                    {"\n"}
                  </span>)}
              </code>
            </pre>
          </CodeBlock>
        </div>
      </div>

      <div className="hf-ve-panel">
        <div className="hf-ve-head">
          <span className="hf-ve-title">Customize</span>
          <button type="button" onClick={() => {
    setValues(defaults);
    setNotes({});
  }} disabled={!dirty} className="hf-ve-btn hf-ve-tint">
            Reset
          </button>
        </div>
        <div className="hf-ve-grid">
          {variables.map(v => <div key={v.id}>
              <div className="hf-ve-row">
                <label className="hf-ve-label">{v.label ?? v.id}</label>
                <span className="hf-ve-value">{readout(v, values[v.id])}</span>
              </div>
              {control(v, values[v.id], next => setValues(prev => ({
    ...prev,
    [v.id]: next
  })), notes[v.id], note => setNotes(prev => ({
    ...prev,
    [v.id]: note
  })), setTyping)}
              {v.description && <p className="hf-ve-desc">{v.description}</p>}
            </div>)}
        </div>
      </div>
    </div>;
};

export const InstallCommand = ({command, item}) => {
  const [copied, setCopied] = React.useState(false);
  const [tuned, setTuned] = React.useState("");
  React.useEffect(() => {
    if (!item) return;
    const read = () => {
      try {
        const raw = new URLSearchParams(window.location.search).get(`vars-${item}`);
        if (!raw) return setTuned("");
        const parsed = JSON.parse(raw);
        if (!parsed || typeof parsed !== "object" || Array.isArray(parsed)) return setTuned("");
        if (Object.keys(parsed).length === 0) return setTuned("");
        setTuned(` --vars '${JSON.stringify(parsed)}'`);
      } catch {
        setTuned("");
      }
    };
    read();
    window.addEventListener("hf-vars-changed", read);
    window.addEventListener("popstate", read);
    return () => {
      window.removeEventListener("hf-vars-changed", read);
      window.removeEventListener("popstate", read);
    };
  }, [item]);
  const fullCommand = `${command}${tuned}`;
  const copy = async () => {
    try {
      if (navigator.clipboard && window.isSecureContext) {
        await navigator.clipboard.writeText(fullCommand);
      } else {
        const previous = document.activeElement;
        const scratch = document.createElement("textarea");
        scratch.value = fullCommand;
        scratch.setAttribute("readonly", "");
        scratch.style.position = "fixed";
        scratch.style.opacity = "0";
        document.body.appendChild(scratch);
        scratch.select();
        document.execCommand("copy");
        document.body.removeChild(scratch);
        previous?.focus?.();
      }
      setCopied(true);
      setTimeout(() => setCopied(false), 2000);
    } catch {}
  };
  return <div className="hf-install-command not-prose my-4 flex items-stretch overflow-hidden rounded-xl border border-zinc-200 bg-zinc-50 dark:border-zinc-800 dark:bg-zinc-900">
      <code className="flex-1 overflow-x-auto whitespace-nowrap border-r border-zinc-200 px-4 py-3 font-mono text-sm text-zinc-800 dark:border-zinc-800 dark:text-zinc-100">
        {fullCommand}
      </code>
      <button type="button" onClick={copy} data-copied={copied ? "true" : "false"} aria-label={`Copy ${command} to the clipboard`} className="hf-install-copy">
        <svg className="hf-install-copy-clipboard" xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 18 18" fill="none" stroke="currentColor" strokeWidth="1.5" strokeLinecap="round" strokeLinejoin="round" aria-hidden="true">
          <path d="M14.25 5.25H7.25C6.14543 5.25 5.25 6.14543 5.25 7.25V14.25C5.25 15.3546 6.14543 16.25 7.25 16.25H14.25C15.3546 16.25 16.25 15.3546 16.25 14.25V7.25C16.25 6.14543 15.3546 5.25 14.25 5.25Z" />
          <path d="M2.80103 11.998L1.77203 5.07397C1.61003 3.98097 2.36403 2.96397 3.45603 2.80197L10.38 1.77297C11.313 1.63397 12.19 2.16297 12.528 3.00097" />
        </svg>
        <svg className="hf-install-copy-check" xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 18 18" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round" aria-hidden="true">
          <path d="M2.75 9.5L6.5 13.25L15.25 4.5" />
        </svg>
      </button>
      <span className="hf-install-copy-status" role="status" aria-live="polite">
        {copied ? "Copied" : ""}
      </span>
    </div>;
};

<VariablesExplorer previewSrc="/public/catalog/blocks/rack-focus.json" compositionId="rack-focus" compositionSrc="compositions/rack-focus.html" variables={[{"id":"nearfocus","type":"number","label":"Near focal distance","default":1.2,"min":0.2,"max":100,"step":0.05,"unit":"m"},{"id":"farfocus","type":"number","label":"Far focal distance","default":80,"min":0.3,"max":400,"step":0.5,"unit":"m"},{"id":"focallength","type":"number","label":"Focal length","default":85,"min":12,"max":300,"step":1,"unit":"mm"},{"id":"aperture","type":"number","label":"Aperture (f-number)","default":1.8,"min":0.95,"max":22,"step":0.05},{"id":"blades","type":"number","label":"Aperture blades (bokeh shape)","default":6,"min":3,"max":14,"step":1},{"id":"catseye","type":"number","label":"Cat eye clipping at the corners","default":0.62,"min":0,"max":1,"step":0.02},{"id":"pullstart","type":"number","label":"Pull start","default":1.2,"min":0,"max":30,"step":0.05,"unit":"s"},{"id":"pullduration","type":"number","label":"Pull duration","default":3.2,"min":0.1,"max":30,"step":0.05,"unit":"s"},{"id":"pullease","type":"string","label":"Pull easing (GSAP ease)","default":"power2.inOut","placeholder":"power2.inOut"},{"id":"bokeh","type":"number","label":"Bokeh exposure","default":1,"min":0,"max":3,"step":0.05},{"id":"backdrop","type":"color","label":"Backdrop","default":"#05060a"}]}>
  ```html rack-focus.html theme={null}
  <!doctype html>
  <html lang="en">
    <head>
      <meta charset="utf-8" />
      <meta name="viewport" content="width=1920, height=1080" />
      <title>Rack Focus</title>
      <script src="https://cdn.jsdelivr.net/npm/gsap@3.14.2/dist/gsap.min.js"></script>
      <!--
        RACK FOCUS: a focus pull with real aperture bokeh.

        WHAT THIS NEEDS TO READ AT ALL
        ------------------------------
        A focus pull is a depth effect. It only reads when the frame holds
        content at two clearly separated depths: something near the lens and
        something far behind it. Point it at flat, single-plane content and
        nothing happens, exactly like a dolly zoom on a flat card.

        This block therefore carries its own depth-layered scene, a night
        exterior built from light sources spread from 1.15 m to 90 m, so it
        works standalone. Every depth is a variable: `nearfocus` is where the
        pull starts, `farfocus` is where it ends, and the scene's two subjects
        sit at those depths. Change them and the subjects move with them.

        WHY THIS IS NOT A BLUR
        ----------------------
        A CSS/Gaussian blur softens everything uniformly. A real defocus turns
        each point of light into an image of the APERTURE, scaled by its circle
        of confusion, so a bright point becomes a hard-edged polygon disc whose
        size grows with distance from the focal plane, and which clips to a
        cat's-eye toward the frame corners. Every light in this scene is
        splatted as an aperture-shaped sprite at its own circle of confusion.

        CIRCLE OF CONFUSION, from three.js BokehShader2 (MIT), Martins Upitis
        --------------------------------------------------------------------
        Read from examples/jsm/shaders/BokehShader2.js:

            float CoC = 0.03;              // circle of confusion in mm
                                           // (35mm film = 0.03mm)
            float f = focalLength;         // mm
            float d = fDepth * 1000.0;     // focal plane in mm
            float o = depth  * 1000.0;     // object depth in mm
            float a = (o * f) / (o - f);
            float b = (d * f) / (d - f);
            float c = (d - f) / (d * fstop * CoC);
            blur = abs(a - b) * c;

        `blur` comes out in units of that 0.03 mm acceptable-sharpness circle,
        so the defocus DIAMETER on the sensor is `blur * 0.03` mm, which this
        block converts to pixels with the sensor width. Same constants, same
        formula, independently written, no code copied. This agrees with the
        Zeiss thin-lens form CoC = (f²/N)·|1/S - 1/U| for S >> f.

        Aperture shape is the community-standard regular-polygon boundary
        d(θ) = cos(π/n) / cos(mod(θ, 2π/n) - π/n), n = blade count (real
        irises ship 5, 6, 8 or 9 blades). Cat's-eye clipping is the aperture
        intersected with two barrel openings offset along the radial direction,
        which is the actual mechanism of mechanical vignetting.

        DETERMINISM
        -----------
        State at frame N is computed from N. The focal distance is a closed-form
        function of t, every circle of confusion follows from a static depth and
        that focal distance, and the scene point cloud is built once from a
        seeded PRNG. No accumulation, no clocks, no unseeded randomness.
      -->
      <style>
        *,
        *::before,
        *::after {
          margin: 0;
          padding: 0;
          box-sizing: border-box;
        }
        body {
          background: #000;
          overflow: hidden;
        }
        #rf-root {
          position: relative;
          width: 1920px;
          height: 1080px;
          overflow: hidden;
        }
        #rf-backdrop {
          position: absolute;
          inset: 0;
          background: #05060a;
        }
        #rf-canvas {
          position: absolute;
          top: 0;
          left: 0;
          width: 1920px;
          height: 1080px;
        }
      </style>
    </head>
    <body>
      <div
        id="rf-root"
        data-composition-id="rack-focus"
        data-root="true"
        data-width="1920"
        data-height="1080"
        data-start="0"
        data-duration="6"
        data-composition-variables='[
          {"id":"nearfocus","type":"number","label":"Near focal distance","default":1.2,"min":0.2,"max":100,"step":0.05,"unit":"m"},
          {"id":"farfocus","type":"number","label":"Far focal distance","default":80,"min":0.3,"max":400,"step":0.5,"unit":"m"},
          {"id":"focallength","type":"number","label":"Focal length","default":85,"min":12,"max":300,"step":1,"unit":"mm"},
          {"id":"aperture","type":"number","label":"Aperture (f-number)","default":1.8,"min":0.95,"max":22,"step":0.05},
          {"id":"blades","type":"number","label":"Aperture blades (bokeh shape)","default":6,"min":3,"max":14,"step":1},
          {"id":"catseye","type":"number","label":"Cat eye clipping at the corners","default":0.62,"min":0,"max":1,"step":0.02},
          {"id":"pullstart","type":"number","label":"Pull start","default":1.2,"min":0,"max":30,"step":0.05,"unit":"s"},
          {"id":"pullduration","type":"number","label":"Pull duration","default":3.2,"min":0.1,"max":30,"step":0.05,"unit":"s"},
          {"id":"pullease","type":"string","label":"Pull easing (GSAP ease)","default":"power2.inOut","placeholder":"power2.inOut"},
          {"id":"bokeh","type":"number","label":"Bokeh exposure","default":1,"min":0,"max":3,"step":0.05},
          {"id":"backdrop","type":"color","label":"Backdrop","default":"#05060a"}
        ]'
      >
        <div id="rf-backdrop"></div>
        <canvas id="rf-canvas" width="1920" height="1080"></canvas>

        <!-- Driver clip: gives HyperFrames a timed element to own on track 0. -->
        <div
          id="rf-drv"
          class="clip"
          data-start="0"
          data-duration="6"
          data-track-index="0"
          style="position: absolute; width: 1px; height: 1px; opacity: 0; pointer-events: none"
        ></div>
      </div>

      <script>
        (function () {
          var DUR = 6;
          var W = 1920;
          var H = 1080;

          // 36mm-wide sensor, 16:9 active area. Pixels per millimetre is the
          // only thing the projection needs, and it is the same on both axes.
          var SENSOR_W_MM = 36;
          var PX_PER_MM = W / SENSOR_W_MM;

          // BokehShader2's acceptable-sharpness circle, in mm (35mm film).
          var COC_MM = 0.03;

          // Defocus is clamped so a wildly out-of-range focus setting cannot
          // splat sprites the size of the frame. BokehShader2 clamps the same
          // quantity with its `maxblur` uniform.
          var MAX_COC_R_PX = 0.1 * H;
          // Smallest sprite half-width. Below roughly one pixel a splat is an
          // aliasing machine, so points in focus bottom out here.
          var MIN_R_PX = 0.75;

          var V = (window.__hyperframes && window.__hyperframes.getVariables()) || {};
          var CS = getComputedStyle(document.getElementById("rf-root"));

          // The runtime defines every declared variable as `--<slug>` on the
          // root (packages/core/src/tokenSlug.ts), so a host stylesheet can
          // override one there too. Read the custom property first, fall back
          // to the declared value when it is unset.
          function raw(id) {
            var css = CS.getPropertyValue("--" + id.toLowerCase()).trim();
            return css !== "" ? css : V[id];
          }
          function num(id, fallback) {
            var n = parseFloat(raw(id));
            return isFinite(n) ? n : fallback;
          }

          var NEAR = num("nearfocus", 1.2);
          var FAR = num("farfocus", 80);
          var FOCAL = num("focallength", 85);
          var FSTOP = num("aperture", 1.8);
          var BLADES = Math.max(3, Math.round(num("blades", 6)));
          var CATSEYE = num("catseye", 0.62);
          var PULL_START = num("pullstart", 1.2);
          var PULL_DUR = Math.max(0.001, num("pullduration", 3.2));
          var BOKEH = num("bokeh", 1);
          var EASE_NAME = String(raw("pullease") || "power2.inOut");
          var BACKDROP =
            typeof raw("backdrop") === "string" && raw("backdrop") ? raw("backdrop") : "#05060a";

          document.getElementById("rf-backdrop").style.background = BACKDROP;

          var EASE = gsap.parseEase(EASE_NAME) || gsap.parseEase("power2.inOut");

          // A focus ring is roughly linear in dioptres, not in metres: a rack
          // from 1.2m to 80m spends its first millimetre of barrel rotation
          // crossing most of the distance. Interpolating 1/distance is what
          // makes the pull travel evenly instead of snapping to the far plane.
          function focusAt(t) {
            var u = Math.min(1, Math.max(0, (t - PULL_START) / PULL_DUR));
            var e = EASE(u);
            var inv = 1 / NEAR + (1 / FAR - 1 / NEAR) * e;
            return 1 / inv;
          }

          // ── Scene ────────────────────────────────────────────────────────
          // A night exterior: a string of practical lights right in front of
          // the lens, a lit city block far behind it, and scattered lights
          // through every depth between so the pull reads as a continuous
          // travel rather than a cut between two planes.

          function mulberry32(a) {
            return function () {
              a |= 0;
              a = (a + 0x6d2b79f5) | 0;
              var t = Math.imul(a ^ (a >>> 15), 1 | a);
              t = (t + Math.imul(t ^ (t >>> 7), 61 | t)) ^ t;
              return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
            };
          }
          var rnd = mulberry32(0x5eed1a3);
          function rr(lo, hi) {
            return lo + (hi - lo) * rnd();
          }

          // x, y in metres (y up, origin on the optical axis), z in metres,
          // r0 = the light's own physical radius in metres, b = peak
          // brightness when perfectly in focus (values above 1 are highlights
          // that clip, which is exactly why they stay visible once spread
          // across a bokeh disc), rgb = colour.
          var P = [];
          function light(x, y, z, r0, b, c) {
            P.push(x, y, z, r0, b, c[0], c[1], c[2]);
          }

          var TUNGSTEN = [1.0, 0.74, 0.45];
          var FILAMENT = [1.0, 0.9, 0.74];
          var WIRE = [0.86, 0.74, 0.6];
          var WARM_WIN = [1.0, 0.79, 0.52];
          var COOL_WIN = [0.6, 0.75, 1.0];
          var SIGN_A = [0.35, 0.95, 1.0];
          var SIGN_B = [1.0, 0.42, 0.72];

          // Half the frame's width, in metres, at depth z. Both subjects are
          // laid out against the reference framing (85mm, 1.2m / 80m) and then
          // scaled by this, so retuning the lens or either focal distance moves
          // the subjects with the frame instead of pushing them out of it.
          function halfW(z) {
            return (0.5 * SENSOR_W_MM * z) / FOCAL;
          }

          // Near subject: a catenary string of bulbs at `nearfocus`. The wire is
          // what makes "sharp" unmistakable, a one-pixel line either resolves
          // or it does not, and the filament inside each bulb is the second cue.
          var NEAR_Z = NEAR;
          var NS = halfW(NEAR_Z) / 0.25412;
          var X_END = 0.4;
          var SAG_A = 0.3;
          var SAG = 0.1;
          var COSH_END = Math.cosh(X_END / SAG_A);
          function stringY(x) {
            var s = (COSH_END - Math.cosh(x / SAG_A)) / (COSH_END - 1);
            return 0.075 - SAG * s - 0.035 * (x / X_END);
          }
          function stringZ(x) {
            return NEAR_Z + 0.05 * (x / X_END);
          }
          for (var i = 0; i < 1100; i++) {
            var wx = -0.42 + (0.84 * i) / 1099;
            light(wx * NS, stringY(wx) * NS, stringZ(wx), 0.0006 * NS, 1.4, WIRE);
          }
          for (var k = -5; k <= 5; k++) {
            var bx = k * 0.085;
            var by = stringY(bx) - 0.011;
            var bz = stringZ(bx);
            light(bx * NS, by * NS, bz, 0.006 * NS, 26, TUNGSTEN);
            light((bx - 0.0022) * NS, by * NS, bz, 0.0006 * NS, 7, FILAMENT);
            light(bx * NS, (by - 0.0022) * NS, bz, 0.0006 * NS, 7, FILAMENT);
            light((bx + 0.0022) * NS, by * NS, bz, 0.0006 * NS, 7, FILAMENT);
          }

          // Far subject: three lit towers plus a dense LED sign strip, sitting
          // around `farfocus`. The sign's pitch is fine enough that it only
          // resolves into separate lamps when focus actually arrives.
          var FAR_Z = FAR;
          var FS = halfW(FAR_Z) / 16.941;
          function tower(cx, hw, topY, botY, cols, rows, z, lit) {
            for (var c = 0; c < cols; c++) {
              for (var r = 0; r < rows; r++) {
                if (rnd() > lit) continue;
                var x = cx - hw + (2 * hw * (c + 0.5)) / cols;
                var y = botY + ((topY - botY) * (r + 0.5)) / rows;
                var cool = rnd() < 0.28;
                light(x, y, z + rr(-0.4, 0.4) * FS, 0.24 * FS, rr(9, 20), cool ? COOL_WIN : WARM_WIN);
              }
            }
          }
          tower(-9.5 * FS, 3.5 * FS, 9.6 * FS, -4.0 * FS, 6, 14, FAR_Z * 1.03, 0.34);
          tower(2.0 * FS, 4.5 * FS, 6.4 * FS, -4.0 * FS, 8, 12, FAR_Z * 0.98, 0.3);
          tower(12.5 * FS, 3.0 * FS, 11.0 * FS, -4.0 * FS, 5, 15, FAR_Z * 1.08, 0.36);
          for (var s = 0; s < 40; s++) {
            var sx = (-5.5 + (11 * s) / 39) * FS;
            var mixc = s / 39;
            var sc = [
              SIGN_A[0] + (SIGN_B[0] - SIGN_A[0]) * mixc,
              SIGN_A[1] + (SIGN_B[1] - SIGN_A[1]) * mixc,
              SIGN_A[2] + (SIGN_B[2] - SIGN_A[2]) * mixc,
            ];
            light(sx, -5.0 * FS, FAR_Z * 0.99, 0.1 * FS, 7, sc);
            light(sx, -5.55 * FS, FAR_Z * 0.99, 0.1 * FS, 7, sc);
          }

          // Everything between. Depth is drawn log-uniform between the two
          // subjects and the screen position is uniform, so the mid-ground
          // stays evenly spread whatever the two focal distances are.
          var Z_LO = Math.min(NEAR_Z, FAR_Z) * 1.9;
          var Z_HI = Math.max(NEAR_Z, FAR_Z) * 0.85;
          for (var m = 0; m < 90; m++) {
            var z = Z_LO * Math.pow(Z_HI / Z_LO, rnd());
            var halfWm = (0.5 * SENSOR_W_MM * z) / FOCAL;
            var halfHm = (halfWm * H) / W;
            var warm = rnd() < 0.66;
            light(
              rr(-1.05, 1.05) * halfWm,
              rr(-1.0, 0.75) * halfHm,
              z,
              rr(0.006, 0.05) * (z / 12),
              rr(5, 18),
              warm ? WARM_WIN : COOL_WIN,
            );
          }

          // ── GL ───────────────────────────────────────────────────────────
          var canvas = document.getElementById("rf-canvas");
          var gl =
            canvas.getContext("webgl", {
              alpha: true,
              antialias: false,
              depth: false,
              stencil: false,
              preserveDrawingBuffer: true,
              powerPreference: "high-performance",
            }) ||
            canvas.getContext("experimental-webgl", {
              alpha: true,
              preserveDrawingBuffer: true,
            });

          var VERT = [
            "precision highp float;",
            "attribute vec2 aCorner;", // -1..1 quad corner
            "attribute vec3 aPos;", // metres, y up, z away from the lens
            "attribute vec2 aSize;", // x = own radius (m), y = in-focus peak
            "attribute vec3 aColor;",
            "uniform vec2 uRes;",
            "uniform float uPxPerMm;",
            "uniform float uFocal;", // mm
            "uniform float uFocus;", // metres
            "uniform float uFstop;",
            "uniform float uCoCmm;",
            "uniform float uMaxR;",
            "uniform float uMinR;",
            "uniform float uCatsEye;",
            "uniform float uBokeh;",
            "varying vec2 vQ;",
            "varying vec3 vColor;",
            "varying float vGain;",
            "varying float vShape;",
            "varying float vAA;",
            "varying vec2 vRadial;",
            "varying float vCat;",
            "void main() {",
            "  float z = max(aPos.z, 0.001);",
            "  float ppm = uPxPerMm * uFocal / z;", // pixels per metre at this depth
            "  vec2 centre = uRes * 0.5 + aPos.xy * ppm;",
            "  float r0 = max(aSize.x * ppm, uMinR);",
            "",
            "  // BokehShader2's circle of confusion, in units of uCoCmm.",
            "  float f = uFocal;",
            "  float d = uFocus * 1000.0;",
            "  float o = z * 1000.0;",
            "  float a = (o * f) / max(o - f, 1e-4);",
            "  float b = (d * f) / max(d - f, 1e-4);",
            "  float c = (d - f) / max(d * uFstop * uCoCmm, 1e-6);",
            "  float blur = abs(a - b) * c;",
            "  // -> defocus diameter in mm -> pixels -> radius.",
            "  float cocR = min(blur * uCoCmm * uPxPerMm * 0.5, uMaxR);",
            "",
            "  // A finite source convolved with the defocus disc: radii add in",
            "  // quadrature. Flux is conserved, so peak brightness falls as the",
            "  // inverse square of the radius. That single term is why an",
            "  // in-focus lamp clips to white and a defocused one is a readable",
            "  // disc instead of a smear.",
            "  float R = sqrt(r0 * r0 + cocR * cocR);",
            "  vGain = aSize.y * uBokeh * (r0 * r0) / (R * R);",
            "  // Near focus the sprite is the lamp (round); far from it the",
            "  // sprite is an image of the aperture (polygonal).",
            "  vShape = (cocR * cocR) / (cocR * cocR + r0 * r0);",
            "  vAA = 1.0 / max(R, 0.5);",
            "  vColor = aColor;",
            "  vQ = aCorner;",
            "",
            "  // Mechanical vignetting: the barrel openings clip the aperture",
            "  // harder the further the sprite sits from the optical axis.",
            "  vec2 off = centre - uRes * 0.5;",
            "  float rad = length(off);",
            "  vRadial = rad > 1.0 ? off / rad : vec2(1.0, 0.0);",
            "  vCat = uCatsEye * min(1.0, rad / (length(uRes) * 0.5));",
            "",
            "  // A light spread thin enough to land under half a display code",
            "  // value contributes nothing but fill rate. Culling it here is what",
            "  // keeps a 900-point wire from splatting 900 invisible discs the",
            "  // moment it goes out of focus.",
            "  if (vGain < 0.0015) {",
            "    gl_Position = vec4(2.0, 2.0, 2.0, 1.0);",
            "    return;",
            "  }",
            "",
            "  vec2 p = centre + aCorner * R;",
            "  gl_Position = vec4((p / uRes) * 2.0 - 1.0, 0.0, 1.0);",
            "}",
          ].join("\n");

          var FRAG = [
            "precision highp float;",
            "varying vec2 vQ;",
            "varying vec3 vColor;",
            "varying float vGain;",
            "varying float vShape;",
            "varying float vAA;",
            "varying vec2 vRadial;",
            "varying float vCat;",
            "uniform float uBlades;",
            "const float PI = 3.14159265;",
            "void main() {",
            "  float r = length(vQ);",
            "  if (r > 1.0) discard;",
            "  float th = r > 1e-5 ? atan(vQ.y, vQ.x) : 0.0;",
            "",
            "  // Regular-polygon aperture boundary: circumradius 1 at a blade",
            "  // vertex, cos(PI/n) at a blade midpoint.",
            "  float n = uBlades;",
            "  float seg = 2.0 * PI / n;",
            "  float poly = cos(PI / n) / cos(mod(th, seg) - PI / n);",
            "  float bound = mix(1.0, poly, vShape);",
            "",
            "  float cov = smoothstep(bound, bound - vAA, r);",
            "  // Two offset barrel openings cut the disc from opposite sides,",
            "  // which is what turns a corner bokeh into a cat's eye.",
            "  float cut = vCat * vShape;",
            "  cov *= smoothstep(1.0, 1.0 - vAA, length(vQ - vRadial * cut));",
            "  cov *= smoothstep(1.0, 1.0 - vAA, length(vQ + vRadial * cut));",
            "",
            "  gl_FragColor = vec4(vColor * (vGain * cov), 1.0);",
            "}",
          ].join("\n");

          var uni = {};
          var ready = false;
          var count = 0;

          function compile(type, src) {
            var sh = gl.createShader(type);
            gl.shaderSource(sh, src);
            gl.compileShader(sh);
            if (!gl.getShaderParameter(sh, gl.COMPILE_STATUS)) {
              throw new Error("rack-focus shader: " + gl.getShaderInfoLog(sh));
            }
            return sh;
          }

          function hexToRgb(hex) {
            var h = String(hex).trim().replace("#", "");
            if (h.length === 3) h = h[0] + h[0] + h[1] + h[1] + h[2] + h[2];
            var v = parseInt(h, 16);
            if (!isFinite(v)) return [0.02, 0.024, 0.039];
            return [((v >> 16) & 255) / 255, ((v >> 8) & 255) / 255, (v & 255) / 255];
          }
          var BG = hexToRgb(BACKDROP);

          if (gl) {
            var prog = gl.createProgram();
            gl.attachShader(prog, compile(gl.VERTEX_SHADER, VERT));
            gl.attachShader(prog, compile(gl.FRAGMENT_SHADER, FRAG));
            gl.linkProgram(prog);
            if (!gl.getProgramParameter(prog, gl.LINK_STATUS)) {
              throw new Error("rack-focus link: " + gl.getProgramInfoLog(prog));
            }
            gl.useProgram(prog);

            // Six vertices per light: two triangles carrying the same point
            // payload and four distinct corner offsets.
            var CORNERS = [
              [-1, -1],
              [1, -1],
              [1, 1],
              [-1, -1],
              [1, 1],
              [-1, 1],
            ];
            var n = P.length / 8;
            count = n * 6;
            var STRIDE = 10;
            var data = new Float32Array(count * STRIDE);
            var w = 0;
            for (var pi = 0; pi < n; pi++) {
              var o = pi * 8;
              for (var ci = 0; ci < 6; ci++) {
                data[w++] = CORNERS[ci][0];
                data[w++] = CORNERS[ci][1];
                data[w++] = P[o];
                data[w++] = P[o + 1];
                data[w++] = P[o + 2];
                data[w++] = P[o + 3];
                data[w++] = P[o + 4];
                data[w++] = P[o + 5];
                data[w++] = P[o + 6];
                data[w++] = P[o + 7];
              }
            }

            var buf = gl.createBuffer();
            gl.bindBuffer(gl.ARRAY_BUFFER, buf);
            gl.bufferData(gl.ARRAY_BUFFER, data, gl.STATIC_DRAW);
            var BYTES = STRIDE * 4;
            [
              ["aCorner", 2, 0],
              ["aPos", 3, 8],
              ["aSize", 2, 20],
              ["aColor", 3, 28],
            ].forEach(function (spec) {
              var loc = gl.getAttribLocation(prog, spec[0]);
              gl.enableVertexAttribArray(loc);
              gl.vertexAttribPointer(loc, spec[1], gl.FLOAT, false, BYTES, spec[2]);
            });

            [
              "uRes",
              "uPxPerMm",
              "uFocal",
              "uFocus",
              "uFstop",
              "uCoCmm",
              "uMaxR",
              "uMinR",
              "uCatsEye",
              "uBlades",
              "uBokeh",
            ].forEach(function (nm) {
              uni[nm] = gl.getUniformLocation(prog, nm);
            });

            gl.viewport(0, 0, W, H);
            gl.uniform2f(uni.uRes, W, H);
            gl.uniform1f(uni.uPxPerMm, PX_PER_MM);
            gl.uniform1f(uni.uFocal, FOCAL);
            gl.uniform1f(uni.uFstop, FSTOP);
            gl.uniform1f(uni.uCoCmm, COC_MM);
            gl.uniform1f(uni.uMaxR, MAX_COC_R_PX);
            gl.uniform1f(uni.uMinR, MIN_R_PX);
            gl.uniform1f(uni.uCatsEye, CATSEYE);
            gl.uniform1f(uni.uBlades, BLADES);
            gl.uniform1f(uni.uBokeh, BOKEH);

            // Light adds to light. Overlapping bokeh discs are brighter where
            // they cross, which is the whole texture of a bokeh field.
            gl.disable(gl.DEPTH_TEST);
            gl.enable(gl.BLEND);
            gl.blendFunc(gl.ONE, gl.ONE);
            ready = true;
          }

          // Every frame is computed from t alone: the focal distance is a
          // closed-form function of t, and each sprite's circle of confusion
          // falls out of its own static depth and that distance.
          function draw(t) {
            if (!ready) return;
            gl.uniform1f(uni.uFocus, focusAt(t));
            gl.clearColor(BG[0], BG[1], BG[2], 1);
            gl.clear(gl.COLOR_BUFFER_BIT);
            gl.drawArrays(gl.TRIANGLES, 0, count);
            gl.flush();
          }

          window.__timelines = window.__timelines || {};
          var tl = gsap.timeline({ paused: true });

          // The canvas is repainted from a property SETTER, not from onUpdate:
          // gsap's seek(t) suppresses events by default, so an onUpdate callback
          // silently never fires on a scrub and the canvas freezes on frame 0.
          // Tweened values are always written during render, suppressed or not,
          // so this fires on every seek, and hands us the frame time directly.
          var driver = { _t: 0 };
          Object.defineProperty(driver, "t", {
            get: function () {
              return this._t;
            },
            set: function (v) {
              this._t = v;
              draw(v);
            },
          });
          tl.to(driver, { t: DUR, duration: DUR, ease: "none" }, 0);
          window.__timelines["rack-focus"] = tl;

          draw(0);
        })();
      </script>
    </body>
  </html>
  ```
</VariablesExplorer>

## Install

<InstallCommand command="npx hyperframes add rack-focus" item="rack-focus" />

That writes one file: `compositions/rack-focus.html`.

## Add it to your video

It runs for 6 seconds at 1920×1080. Paste this into your composition:

```html index.html theme={null}
<div
  data-composition-id="rack-focus"
  data-composition-src="compositions/rack-focus.html"
  data-start="0"
  data-duration="6"
  data-track-index="1"
  data-width="1920"
  data-height="1080"
></div>
```

Move it in time with `data-start`. Put it on a different timeline row with
`data-track-index`. See [data attributes](/concepts/data-attributes) for the rest.

## Change how it looks

Set these CSS variables on the block:

* `--nearfocus` — Near focal distance in metres (where the pull starts and the near subject sits). Defaults to `1.2`.
* `--farfocus` — Far focal distance in metres (where the pull ends and the far subject sits). Defaults to `80`.
* `--focallength` — Focal length in mm (longer lens = shallower depth of field). Defaults to `85`.
* `--aperture` — Aperture f-number (lower = bigger bokeh). Defaults to `1.8`.
* `--blades` — Aperture blade count, the bokeh polygon's sides. Defaults to `6`.
* `--catseye` — Cat's-eye clipping at the frame corners (mechanical vignetting). Defaults to `0.62`.
* `--pullstart` — Seconds held on the near subject before the pull starts. Defaults to `1.2`.
* `--pullduration` — Pull duration in seconds. Defaults to `3.2`.
* `--pullease` — Pull easing (any GSAP ease name). Defaults to `power2.inOut`.
* `--bokeh` — Bokeh exposure. Defaults to `1`.
* `--backdrop` — Backdrop. Defaults to `#05060a`.

## Variables

Every one of these has a default, so the piece works untouched. Set the ones you
want to change on the element:

| Variable       | Default        | Accepts                  | What it does |
| -------------- | -------------- | ------------------------ | ------------ |
| `nearfocus`    | `1.2`          | 0.2m to 100m, step 0.05m |              |
| `farfocus`     | `80`           | 0.3m to 400m, step 0.5m  |              |
| `focallength`  | `85`           | 12mm to 300mm, step 1mm  |              |
| `aperture`     | `1.8`          | 0.95 to 22, step 0.05    |              |
| `blades`       | `6`            | 3 to 14, step 1          |              |
| `catseye`      | `0.62`         | 0 to 1, step 0.02        |              |
| `pullstart`    | `1.2`          | 0s to 30s, step 0.05s    |              |
| `pullduration` | `3.2`          | 0.1s to 30s, step 0.05s  |              |
| `pullease`     | `power2.inOut` | string                   |              |
| `bokeh`        | `1`            | 0 to 3, step 0.05        |              |
| `backdrop`     | `#05060a`      | color                    |              |

Set them with `data-variable-values` on the element that mounts it. These are the
defaults, so this behaves exactly like the preview above until you change one:

```html wrap theme={null}
<div
  data-composition-id="rack-focus"
  data-composition-src="compositions/rack-focus.html"
  data-variable-values='{"nearfocus":1.2,"farfocus":80,"focallength":85,"aperture":1.8,"blades":6,"catseye":0.62,"pullstart":1.2,"pullduration":3.2,"pullease":"power2.inOut","bokeh":1,"backdrop":"#05060a"}'
></div>
```

## Source

<Accordion title={`rack-focus.html`}>
  ```html theme={null}
  <!doctype html>
  <html lang="en">
    <head>
      <meta charset="utf-8" />
      <meta name="viewport" content="width=1920, height=1080" />
      <title>Rack Focus</title>
      <script src="https://cdn.jsdelivr.net/npm/gsap@3.14.2/dist/gsap.min.js"></script>
      <!--
        RACK FOCUS: a focus pull with real aperture bokeh.

        WHAT THIS NEEDS TO READ AT ALL
        ------------------------------
        A focus pull is a depth effect. It only reads when the frame holds
        content at two clearly separated depths: something near the lens and
        something far behind it. Point it at flat, single-plane content and
        nothing happens, exactly like a dolly zoom on a flat card.

        This block therefore carries its own depth-layered scene, a night
        exterior built from light sources spread from 1.15 m to 90 m, so it
        works standalone. Every depth is a variable: `nearfocus` is where the
        pull starts, `farfocus` is where it ends, and the scene's two subjects
        sit at those depths. Change them and the subjects move with them.

        WHY THIS IS NOT A BLUR
        ----------------------
        A CSS/Gaussian blur softens everything uniformly. A real defocus turns
        each point of light into an image of the APERTURE, scaled by its circle
        of confusion, so a bright point becomes a hard-edged polygon disc whose
        size grows with distance from the focal plane, and which clips to a
        cat's-eye toward the frame corners. Every light in this scene is
        splatted as an aperture-shaped sprite at its own circle of confusion.

        CIRCLE OF CONFUSION, from three.js BokehShader2 (MIT), Martins Upitis
        --------------------------------------------------------------------
        Read from examples/jsm/shaders/BokehShader2.js:

            float CoC = 0.03;              // circle of confusion in mm
                                           // (35mm film = 0.03mm)
            float f = focalLength;         // mm
            float d = fDepth * 1000.0;     // focal plane in mm
            float o = depth  * 1000.0;     // object depth in mm
            float a = (o * f) / (o - f);
            float b = (d * f) / (d - f);
            float c = (d - f) / (d * fstop * CoC);
            blur = abs(a - b) * c;

        `blur` comes out in units of that 0.03 mm acceptable-sharpness circle,
        so the defocus DIAMETER on the sensor is `blur * 0.03` mm, which this
        block converts to pixels with the sensor width. Same constants, same
        formula, independently written, no code copied. This agrees with the
        Zeiss thin-lens form CoC = (f²/N)·|1/S - 1/U| for S >> f.

        Aperture shape is the community-standard regular-polygon boundary
        d(θ) = cos(π/n) / cos(mod(θ, 2π/n) - π/n), n = blade count (real
        irises ship 5, 6, 8 or 9 blades). Cat's-eye clipping is the aperture
        intersected with two barrel openings offset along the radial direction,
        which is the actual mechanism of mechanical vignetting.

        DETERMINISM
        -----------
        State at frame N is computed from N. The focal distance is a closed-form
        function of t, every circle of confusion follows from a static depth and
        that focal distance, and the scene point cloud is built once from a
        seeded PRNG. No accumulation, no clocks, no unseeded randomness.
      -->
      <style>
        *,
        *::before,
        *::after {
          margin: 0;
          padding: 0;
          box-sizing: border-box;
        }
        body {
          background: #000;
          overflow: hidden;
        }
        #rf-root {
          position: relative;
          width: 1920px;
          height: 1080px;
          overflow: hidden;
        }
        #rf-backdrop {
          position: absolute;
          inset: 0;
          background: #05060a;
        }
        #rf-canvas {
          position: absolute;
          top: 0;
          left: 0;
          width: 1920px;
          height: 1080px;
        }
      </style>
    </head>
    <body>
      <div
        id="rf-root"
        data-composition-id="rack-focus"
        data-root="true"
        data-width="1920"
        data-height="1080"
        data-start="0"
        data-duration="6"
        data-composition-variables='[
          {"id":"nearfocus","type":"number","label":"Near focal distance","default":1.2,"min":0.2,"max":100,"step":0.05,"unit":"m"},
          {"id":"farfocus","type":"number","label":"Far focal distance","default":80,"min":0.3,"max":400,"step":0.5,"unit":"m"},
          {"id":"focallength","type":"number","label":"Focal length","default":85,"min":12,"max":300,"step":1,"unit":"mm"},
          {"id":"aperture","type":"number","label":"Aperture (f-number)","default":1.8,"min":0.95,"max":22,"step":0.05},
          {"id":"blades","type":"number","label":"Aperture blades (bokeh shape)","default":6,"min":3,"max":14,"step":1},
          {"id":"catseye","type":"number","label":"Cat eye clipping at the corners","default":0.62,"min":0,"max":1,"step":0.02},
          {"id":"pullstart","type":"number","label":"Pull start","default":1.2,"min":0,"max":30,"step":0.05,"unit":"s"},
          {"id":"pullduration","type":"number","label":"Pull duration","default":3.2,"min":0.1,"max":30,"step":0.05,"unit":"s"},
          {"id":"pullease","type":"string","label":"Pull easing (GSAP ease)","default":"power2.inOut","placeholder":"power2.inOut"},
          {"id":"bokeh","type":"number","label":"Bokeh exposure","default":1,"min":0,"max":3,"step":0.05},
          {"id":"backdrop","type":"color","label":"Backdrop","default":"#05060a"}
        ]'
      >
        <div id="rf-backdrop"></div>
        <canvas id="rf-canvas" width="1920" height="1080"></canvas>

        <!-- Driver clip: gives HyperFrames a timed element to own on track 0. -->
        <div
          id="rf-drv"
          class="clip"
          data-start="0"
          data-duration="6"
          data-track-index="0"
          style="position: absolute; width: 1px; height: 1px; opacity: 0; pointer-events: none"
        ></div>
      </div>

      <script>
        (function () {
          var DUR = 6;
          var W = 1920;
          var H = 1080;

          // 36mm-wide sensor, 16:9 active area. Pixels per millimetre is the
          // only thing the projection needs, and it is the same on both axes.
          var SENSOR_W_MM = 36;
          var PX_PER_MM = W / SENSOR_W_MM;

          // BokehShader2's acceptable-sharpness circle, in mm (35mm film).
          var COC_MM = 0.03;

          // Defocus is clamped so a wildly out-of-range focus setting cannot
          // splat sprites the size of the frame. BokehShader2 clamps the same
          // quantity with its `maxblur` uniform.
          var MAX_COC_R_PX = 0.1 * H;
          // Smallest sprite half-width. Below roughly one pixel a splat is an
          // aliasing machine, so points in focus bottom out here.
          var MIN_R_PX = 0.75;

          var V = (window.__hyperframes && window.__hyperframes.getVariables()) || {};
          var CS = getComputedStyle(document.getElementById("rf-root"));

          // The runtime defines every declared variable as `--<slug>` on the
          // root (packages/core/src/tokenSlug.ts), so a host stylesheet can
          // override one there too. Read the custom property first, fall back
          // to the declared value when it is unset.
          function raw(id) {
            var css = CS.getPropertyValue("--" + id.toLowerCase()).trim();
            return css !== "" ? css : V[id];
          }
          function num(id, fallback) {
            var n = parseFloat(raw(id));
            return isFinite(n) ? n : fallback;
          }

          var NEAR = num("nearfocus", 1.2);
          var FAR = num("farfocus", 80);
          var FOCAL = num("focallength", 85);
          var FSTOP = num("aperture", 1.8);
          var BLADES = Math.max(3, Math.round(num("blades", 6)));
          var CATSEYE = num("catseye", 0.62);
          var PULL_START = num("pullstart", 1.2);
          var PULL_DUR = Math.max(0.001, num("pullduration", 3.2));
          var BOKEH = num("bokeh", 1);
          var EASE_NAME = String(raw("pullease") || "power2.inOut");
          var BACKDROP =
            typeof raw("backdrop") === "string" && raw("backdrop") ? raw("backdrop") : "#05060a";

          document.getElementById("rf-backdrop").style.background = BACKDROP;

          var EASE = gsap.parseEase(EASE_NAME) || gsap.parseEase("power2.inOut");

          // A focus ring is roughly linear in dioptres, not in metres: a rack
          // from 1.2m to 80m spends its first millimetre of barrel rotation
          // crossing most of the distance. Interpolating 1/distance is what
          // makes the pull travel evenly instead of snapping to the far plane.
          function focusAt(t) {
            var u = Math.min(1, Math.max(0, (t - PULL_START) / PULL_DUR));
            var e = EASE(u);
            var inv = 1 / NEAR + (1 / FAR - 1 / NEAR) * e;
            return 1 / inv;
          }

          // ── Scene ────────────────────────────────────────────────────────
          // A night exterior: a string of practical lights right in front of
          // the lens, a lit city block far behind it, and scattered lights
          // through every depth between so the pull reads as a continuous
          // travel rather than a cut between two planes.

          function mulberry32(a) {
            return function () {
              a |= 0;
              a = (a + 0x6d2b79f5) | 0;
              var t = Math.imul(a ^ (a >>> 15), 1 | a);
              t = (t + Math.imul(t ^ (t >>> 7), 61 | t)) ^ t;
              return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
            };
          }
          var rnd = mulberry32(0x5eed1a3);
          function rr(lo, hi) {
            return lo + (hi - lo) * rnd();
          }

          // x, y in metres (y up, origin on the optical axis), z in metres,
          // r0 = the light's own physical radius in metres, b = peak
          // brightness when perfectly in focus (values above 1 are highlights
          // that clip, which is exactly why they stay visible once spread
          // across a bokeh disc), rgb = colour.
          var P = [];
          function light(x, y, z, r0, b, c) {
            P.push(x, y, z, r0, b, c[0], c[1], c[2]);
          }

          var TUNGSTEN = [1.0, 0.74, 0.45];
          var FILAMENT = [1.0, 0.9, 0.74];
          var WIRE = [0.86, 0.74, 0.6];
          var WARM_WIN = [1.0, 0.79, 0.52];
          var COOL_WIN = [0.6, 0.75, 1.0];
          var SIGN_A = [0.35, 0.95, 1.0];
          var SIGN_B = [1.0, 0.42, 0.72];

          // Half the frame's width, in metres, at depth z. Both subjects are
          // laid out against the reference framing (85mm, 1.2m / 80m) and then
          // scaled by this, so retuning the lens or either focal distance moves
          // the subjects with the frame instead of pushing them out of it.
          function halfW(z) {
            return (0.5 * SENSOR_W_MM * z) / FOCAL;
          }

          // Near subject: a catenary string of bulbs at `nearfocus`. The wire is
          // what makes "sharp" unmistakable, a one-pixel line either resolves
          // or it does not, and the filament inside each bulb is the second cue.
          var NEAR_Z = NEAR;
          var NS = halfW(NEAR_Z) / 0.25412;
          var X_END = 0.4;
          var SAG_A = 0.3;
          var SAG = 0.1;
          var COSH_END = Math.cosh(X_END / SAG_A);
          function stringY(x) {
            var s = (COSH_END - Math.cosh(x / SAG_A)) / (COSH_END - 1);
            return 0.075 - SAG * s - 0.035 * (x / X_END);
          }
          function stringZ(x) {
            return NEAR_Z + 0.05 * (x / X_END);
          }
          for (var i = 0; i < 1100; i++) {
            var wx = -0.42 + (0.84 * i) / 1099;
            light(wx * NS, stringY(wx) * NS, stringZ(wx), 0.0006 * NS, 1.4, WIRE);
          }
          for (var k = -5; k <= 5; k++) {
            var bx = k * 0.085;
            var by = stringY(bx) - 0.011;
            var bz = stringZ(bx);
            light(bx * NS, by * NS, bz, 0.006 * NS, 26, TUNGSTEN);
            light((bx - 0.0022) * NS, by * NS, bz, 0.0006 * NS, 7, FILAMENT);
            light(bx * NS, (by - 0.0022) * NS, bz, 0.0006 * NS, 7, FILAMENT);
            light((bx + 0.0022) * NS, by * NS, bz, 0.0006 * NS, 7, FILAMENT);
          }

          // Far subject: three lit towers plus a dense LED sign strip, sitting
          // around `farfocus`. The sign's pitch is fine enough that it only
          // resolves into separate lamps when focus actually arrives.
          var FAR_Z = FAR;
          var FS = halfW(FAR_Z) / 16.941;
          function tower(cx, hw, topY, botY, cols, rows, z, lit) {
            for (var c = 0; c < cols; c++) {
              for (var r = 0; r < rows; r++) {
                if (rnd() > lit) continue;
                var x = cx - hw + (2 * hw * (c + 0.5)) / cols;
                var y = botY + ((topY - botY) * (r + 0.5)) / rows;
                var cool = rnd() < 0.28;
                light(x, y, z + rr(-0.4, 0.4) * FS, 0.24 * FS, rr(9, 20), cool ? COOL_WIN : WARM_WIN);
              }
            }
          }
          tower(-9.5 * FS, 3.5 * FS, 9.6 * FS, -4.0 * FS, 6, 14, FAR_Z * 1.03, 0.34);
          tower(2.0 * FS, 4.5 * FS, 6.4 * FS, -4.0 * FS, 8, 12, FAR_Z * 0.98, 0.3);
          tower(12.5 * FS, 3.0 * FS, 11.0 * FS, -4.0 * FS, 5, 15, FAR_Z * 1.08, 0.36);
          for (var s = 0; s < 40; s++) {
            var sx = (-5.5 + (11 * s) / 39) * FS;
            var mixc = s / 39;
            var sc = [
              SIGN_A[0] + (SIGN_B[0] - SIGN_A[0]) * mixc,
              SIGN_A[1] + (SIGN_B[1] - SIGN_A[1]) * mixc,
              SIGN_A[2] + (SIGN_B[2] - SIGN_A[2]) * mixc,
            ];
            light(sx, -5.0 * FS, FAR_Z * 0.99, 0.1 * FS, 7, sc);
            light(sx, -5.55 * FS, FAR_Z * 0.99, 0.1 * FS, 7, sc);
          }

          // Everything between. Depth is drawn log-uniform between the two
          // subjects and the screen position is uniform, so the mid-ground
          // stays evenly spread whatever the two focal distances are.
          var Z_LO = Math.min(NEAR_Z, FAR_Z) * 1.9;
          var Z_HI = Math.max(NEAR_Z, FAR_Z) * 0.85;
          for (var m = 0; m < 90; m++) {
            var z = Z_LO * Math.pow(Z_HI / Z_LO, rnd());
            var halfWm = (0.5 * SENSOR_W_MM * z) / FOCAL;
            var halfHm = (halfWm * H) / W;
            var warm = rnd() < 0.66;
            light(
              rr(-1.05, 1.05) * halfWm,
              rr(-1.0, 0.75) * halfHm,
              z,
              rr(0.006, 0.05) * (z / 12),
              rr(5, 18),
              warm ? WARM_WIN : COOL_WIN,
            );
          }

          // ── GL ───────────────────────────────────────────────────────────
          var canvas = document.getElementById("rf-canvas");
          var gl =
            canvas.getContext("webgl", {
              alpha: true,
              antialias: false,
              depth: false,
              stencil: false,
              preserveDrawingBuffer: true,
              powerPreference: "high-performance",
            }) ||
            canvas.getContext("experimental-webgl", {
              alpha: true,
              preserveDrawingBuffer: true,
            });

          var VERT = [
            "precision highp float;",
            "attribute vec2 aCorner;", // -1..1 quad corner
            "attribute vec3 aPos;", // metres, y up, z away from the lens
            "attribute vec2 aSize;", // x = own radius (m), y = in-focus peak
            "attribute vec3 aColor;",
            "uniform vec2 uRes;",
            "uniform float uPxPerMm;",
            "uniform float uFocal;", // mm
            "uniform float uFocus;", // metres
            "uniform float uFstop;",
            "uniform float uCoCmm;",
            "uniform float uMaxR;",
            "uniform float uMinR;",
            "uniform float uCatsEye;",
            "uniform float uBokeh;",
            "varying vec2 vQ;",
            "varying vec3 vColor;",
            "varying float vGain;",
            "varying float vShape;",
            "varying float vAA;",
            "varying vec2 vRadial;",
            "varying float vCat;",
            "void main() {",
            "  float z = max(aPos.z, 0.001);",
            "  float ppm = uPxPerMm * uFocal / z;", // pixels per metre at this depth
            "  vec2 centre = uRes * 0.5 + aPos.xy * ppm;",
            "  float r0 = max(aSize.x * ppm, uMinR);",
            "",
            "  // BokehShader2's circle of confusion, in units of uCoCmm.",
            "  float f = uFocal;",
            "  float d = uFocus * 1000.0;",
            "  float o = z * 1000.0;",
            "  float a = (o * f) / max(o - f, 1e-4);",
            "  float b = (d * f) / max(d - f, 1e-4);",
            "  float c = (d - f) / max(d * uFstop * uCoCmm, 1e-6);",
            "  float blur = abs(a - b) * c;",
            "  // -> defocus diameter in mm -> pixels -> radius.",
            "  float cocR = min(blur * uCoCmm * uPxPerMm * 0.5, uMaxR);",
            "",
            "  // A finite source convolved with the defocus disc: radii add in",
            "  // quadrature. Flux is conserved, so peak brightness falls as the",
            "  // inverse square of the radius. That single term is why an",
            "  // in-focus lamp clips to white and a defocused one is a readable",
            "  // disc instead of a smear.",
            "  float R = sqrt(r0 * r0 + cocR * cocR);",
            "  vGain = aSize.y * uBokeh * (r0 * r0) / (R * R);",
            "  // Near focus the sprite is the lamp (round); far from it the",
            "  // sprite is an image of the aperture (polygonal).",
            "  vShape = (cocR * cocR) / (cocR * cocR + r0 * r0);",
            "  vAA = 1.0 / max(R, 0.5);",
            "  vColor = aColor;",
            "  vQ = aCorner;",
            "",
            "  // Mechanical vignetting: the barrel openings clip the aperture",
            "  // harder the further the sprite sits from the optical axis.",
            "  vec2 off = centre - uRes * 0.5;",
            "  float rad = length(off);",
            "  vRadial = rad > 1.0 ? off / rad : vec2(1.0, 0.0);",
            "  vCat = uCatsEye * min(1.0, rad / (length(uRes) * 0.5));",
            "",
            "  // A light spread thin enough to land under half a display code",
            "  // value contributes nothing but fill rate. Culling it here is what",
            "  // keeps a 900-point wire from splatting 900 invisible discs the",
            "  // moment it goes out of focus.",
            "  if (vGain < 0.0015) {",
            "    gl_Position = vec4(2.0, 2.0, 2.0, 1.0);",
            "    return;",
            "  }",
            "",
            "  vec2 p = centre + aCorner * R;",
            "  gl_Position = vec4((p / uRes) * 2.0 - 1.0, 0.0, 1.0);",
            "}",
          ].join("\n");

          var FRAG = [
            "precision highp float;",
            "varying vec2 vQ;",
            "varying vec3 vColor;",
            "varying float vGain;",
            "varying float vShape;",
            "varying float vAA;",
            "varying vec2 vRadial;",
            "varying float vCat;",
            "uniform float uBlades;",
            "const float PI = 3.14159265;",
            "void main() {",
            "  float r = length(vQ);",
            "  if (r > 1.0) discard;",
            "  float th = r > 1e-5 ? atan(vQ.y, vQ.x) : 0.0;",
            "",
            "  // Regular-polygon aperture boundary: circumradius 1 at a blade",
            "  // vertex, cos(PI/n) at a blade midpoint.",
            "  float n = uBlades;",
            "  float seg = 2.0 * PI / n;",
            "  float poly = cos(PI / n) / cos(mod(th, seg) - PI / n);",
            "  float bound = mix(1.0, poly, vShape);",
            "",
            "  float cov = smoothstep(bound, bound - vAA, r);",
            "  // Two offset barrel openings cut the disc from opposite sides,",
            "  // which is what turns a corner bokeh into a cat's eye.",
            "  float cut = vCat * vShape;",
            "  cov *= smoothstep(1.0, 1.0 - vAA, length(vQ - vRadial * cut));",
            "  cov *= smoothstep(1.0, 1.0 - vAA, length(vQ + vRadial * cut));",
            "",
            "  gl_FragColor = vec4(vColor * (vGain * cov), 1.0);",
            "}",
          ].join("\n");

          var uni = {};
          var ready = false;
          var count = 0;

          function compile(type, src) {
            var sh = gl.createShader(type);
            gl.shaderSource(sh, src);
            gl.compileShader(sh);
            if (!gl.getShaderParameter(sh, gl.COMPILE_STATUS)) {
              throw new Error("rack-focus shader: " + gl.getShaderInfoLog(sh));
            }
            return sh;
          }

          function hexToRgb(hex) {
            var h = String(hex).trim().replace("#", "");
            if (h.length === 3) h = h[0] + h[0] + h[1] + h[1] + h[2] + h[2];
            var v = parseInt(h, 16);
            if (!isFinite(v)) return [0.02, 0.024, 0.039];
            return [((v >> 16) & 255) / 255, ((v >> 8) & 255) / 255, (v & 255) / 255];
          }
          var BG = hexToRgb(BACKDROP);

          if (gl) {
            var prog = gl.createProgram();
            gl.attachShader(prog, compile(gl.VERTEX_SHADER, VERT));
            gl.attachShader(prog, compile(gl.FRAGMENT_SHADER, FRAG));
            gl.linkProgram(prog);
            if (!gl.getProgramParameter(prog, gl.LINK_STATUS)) {
              throw new Error("rack-focus link: " + gl.getProgramInfoLog(prog));
            }
            gl.useProgram(prog);

            // Six vertices per light: two triangles carrying the same point
            // payload and four distinct corner offsets.
            var CORNERS = [
              [-1, -1],
              [1, -1],
              [1, 1],
              [-1, -1],
              [1, 1],
              [-1, 1],
            ];
            var n = P.length / 8;
            count = n * 6;
            var STRIDE = 10;
            var data = new Float32Array(count * STRIDE);
            var w = 0;
            for (var pi = 0; pi < n; pi++) {
              var o = pi * 8;
              for (var ci = 0; ci < 6; ci++) {
                data[w++] = CORNERS[ci][0];
                data[w++] = CORNERS[ci][1];
                data[w++] = P[o];
                data[w++] = P[o + 1];
                data[w++] = P[o + 2];
                data[w++] = P[o + 3];
                data[w++] = P[o + 4];
                data[w++] = P[o + 5];
                data[w++] = P[o + 6];
                data[w++] = P[o + 7];
              }
            }

            var buf = gl.createBuffer();
            gl.bindBuffer(gl.ARRAY_BUFFER, buf);
            gl.bufferData(gl.ARRAY_BUFFER, data, gl.STATIC_DRAW);
            var BYTES = STRIDE * 4;
            [
              ["aCorner", 2, 0],
              ["aPos", 3, 8],
              ["aSize", 2, 20],
              ["aColor", 3, 28],
            ].forEach(function (spec) {
              var loc = gl.getAttribLocation(prog, spec[0]);
              gl.enableVertexAttribArray(loc);
              gl.vertexAttribPointer(loc, spec[1], gl.FLOAT, false, BYTES, spec[2]);
            });

            [
              "uRes",
              "uPxPerMm",
              "uFocal",
              "uFocus",
              "uFstop",
              "uCoCmm",
              "uMaxR",
              "uMinR",
              "uCatsEye",
              "uBlades",
              "uBokeh",
            ].forEach(function (nm) {
              uni[nm] = gl.getUniformLocation(prog, nm);
            });

            gl.viewport(0, 0, W, H);
            gl.uniform2f(uni.uRes, W, H);
            gl.uniform1f(uni.uPxPerMm, PX_PER_MM);
            gl.uniform1f(uni.uFocal, FOCAL);
            gl.uniform1f(uni.uFstop, FSTOP);
            gl.uniform1f(uni.uCoCmm, COC_MM);
            gl.uniform1f(uni.uMaxR, MAX_COC_R_PX);
            gl.uniform1f(uni.uMinR, MIN_R_PX);
            gl.uniform1f(uni.uCatsEye, CATSEYE);
            gl.uniform1f(uni.uBlades, BLADES);
            gl.uniform1f(uni.uBokeh, BOKEH);

            // Light adds to light. Overlapping bokeh discs are brighter where
            // they cross, which is the whole texture of a bokeh field.
            gl.disable(gl.DEPTH_TEST);
            gl.enable(gl.BLEND);
            gl.blendFunc(gl.ONE, gl.ONE);
            ready = true;
          }

          // Every frame is computed from t alone: the focal distance is a
          // closed-form function of t, and each sprite's circle of confusion
          // falls out of its own static depth and that distance.
          function draw(t) {
            if (!ready) return;
            gl.uniform1f(uni.uFocus, focusAt(t));
            gl.clearColor(BG[0], BG[1], BG[2], 1);
            gl.clear(gl.COLOR_BUFFER_BIT);
            gl.drawArrays(gl.TRIANGLES, 0, count);
            gl.flush();
          }

          window.__timelines = window.__timelines || {};
          var tl = gsap.timeline({ paused: true });

          // The canvas is repainted from a property SETTER, not from onUpdate:
          // gsap's seek(t) suppresses events by default, so an onUpdate callback
          // silently never fires on a scrub and the canvas freezes on frame 0.
          // Tweened values are always written during render, suppressed or not,
          // so this fires on every seek, and hands us the frame time directly.
          var driver = { _t: 0 };
          Object.defineProperty(driver, "t", {
            get: function () {
              return this._t;
            },
            set: function (v) {
              this._t = v;
              draw(v);
            },
          });
          tl.to(driver, { t: DUR, duration: DUR, ease: "none" }, 0);
          window.__timelines["rack-focus"] = tl;

          draw(0);
        })();
      </script>
    </body>
  </html>
  ```
</Accordion>

Tagged `webgl` `shader` `camera` `depth` `cinematic` `showcase`.

## Related topics

* [Browse the complete Catalog](/catalog)
* [Add assets and Catalog items in Studio](/studio/assets-and-blocks)
* [Build a richer composition](/go-further)