> ## Documentation Index
> Fetch the complete documentation index at: https://hyperframes.heygen.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Camera Follow Captions

> One sentence written across a world far larger than the frame. Each word is sized against everything already written, so the block grows geometrically and the camera pulls back at a steady rate to keep landing the new word at the same size. Old words stay lit and simply become small.

export const InstallCommand = ({command}) => {
  const [copied, setCopied] = React.useState(false);
  const copy = async () => {
    try {
      if (navigator.clipboard && window.isSecureContext) {
        await navigator.clipboard.writeText(command);
      } else {
        const previous = document.activeElement;
        const scratch = document.createElement("textarea");
        scratch.value = command;
        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">
        {command}
      </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>;
};

<iframe className="w-full aspect-video rounded-xl border-0 bg-zinc-100 dark:bg-zinc-800" title="caption-camera-follow preview" loading="lazy" srcDoc={`<!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>fetch("/public/catalog/components/caption-camera-follow.json").then(function(r){return r.json()}).then(function(d){var p=document.createElement("hyperframes-player");p.setAttribute("srcdoc",d.html);p.setAttribute("controls","");p.setAttribute("autoplay","");p.setAttribute("loop","");p.setAttribute("muted","");p.setAttribute("poster","https://static.heygen.ai/hyperframes-oss/docs/images/catalog/components/caption-camera-follow.png");document.body.appendChild(p)});<\/script></body></html>`} />

## Install

<InstallCommand command="npx hyperframes add caption-camera-follow" />

That writes one file: `compositions/components/caption-camera-follow.html`.

## Paste it into your composition

Open `compositions/components/caption-camera-follow.html` and copy what is inside into your own composition.

A component has no size or duration of its own. It takes both from the composition
you paste it into.

## 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                                                                                  |
| --------- | ---------- | ------------------------------------ | --------------------------------------------------------------------------------------------- |
| `accent`  | `gold`     | `gold`, `green`, `blue`, `violet`    | Colour of the highlighted words. gold is the original.                                        |
| `framing` | `standard` | `tight`, `standard`, `wide`          | Air the camera leaves around the written block, so the words land larger or smaller in frame. |
| `smear`   | `standard` | `off`, `subtle`, `standard`, `heavy` | Scales the radial motion blur each camera move carries, from none to a heavy streak.          |

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="caption-camera-follow"
  data-composition-src="compositions/components/caption-camera-follow.html"
  data-variable-values='{"accent":"gold","framing":"standard","smear":"standard"}'
></div>
```

## Source

<Accordion title={`caption-camera-follow.html`}>
  ```html theme={null}
  <!doctype html>
  <!--
    caption-camera-follow: the words do not move, the camera does.

    One sentence. Layout is self similar: every new word is sized as a fraction of the
    bounding box of everything written so far, and is dropped either to the right of that
    box or onto a new line below it, alternating. Because each word is measured against a
    box that keeps growing, the box grows geometrically, so the camera pulls back at a
    steady exponential rate and every word arrives at roughly the same size on screen. Old
    words stay lit and simply become small, piling up toward the top left the way
    handwriting fills a page. The last beat carries the same pull back all the way out
    until the whole sentence is readable at once.

    Variables. The script reads each one, falls back to the declared default on
    anything missing or unrecognised, and applies it before the timeline is built.
    Duration, word order and cadence are untouched by them.

      - accent (gold | green | blue | violet, default gold): the colour of the
        highlighted words.
      - framing (tight | standard | wide, default standard): the air the camera
        leaves around the written block. tight lands each word larger in frame,
        wide sits further back. Every move and the closing pull back scale
        together, so the shot stays one continuous camera.
      - smear (off | subtle | standard | heavy, default standard): scales the
        radial motion blur each move carries. off renders every frame sharp.

    On every default the result is identical to the original: gold highlights, a
    1.36 margin around the block and a peak smear of 2.6 percent of frame width.

    Every ease is a cubic bezier written out by hand and solved in this file. No preset is
    used anywhere. Motion blur is radial, the way it reads in real camera footage: each word
    carries its own blur share, scaled by how far that word sits from the centre of the move,
    so the frame smears outward from the point the camera is pushing toward. One shared
    amount variable is tweened per move and every word multiplies it by its own distance
    share, so the whole radial pulse costs one tween instead of fourteen.

    Mount contract: everything lives inside <template>, styles and scripts included, and the
    scripts sit INSIDE the composition root. A host clones template content into its own
    mount and only runs scripts found inside the root; markup left outside is copied without
    its behaviour, which renders a black card with no timeline at all.
  -->
  <html lang="en">
    <head>
      <meta charset="UTF-8" />
      <title>Camera Follow Captions</title>
    </head>
    <body>
      <template>
        <div
          id="root"
          class="clip cf-root"
          data-composition-id="caption-camera-follow"
          data-duration="9"
          data-fps="30"
          data-composition-variables='[
            { "id": "accent", "type": "enum", "role": "style", "label": "Accent", "description": "Colour of the highlighted words. gold is the original.", "default": "gold", "options": [{ "value": "gold", "label": "Gold" }, { "value": "green", "label": "Green" }, { "value": "blue", "label": "Blue" }, { "value": "violet", "label": "Violet" }] },
            { "id": "framing", "type": "enum", "role": "style", "label": "Framing", "description": "Air the camera leaves around the written block, so the words land larger or smaller in frame.", "default": "standard", "options": [{ "value": "tight", "label": "Tight" }, { "value": "standard", "label": "Standard" }, { "value": "wide", "label": "Wide" }] },
            { "id": "smear", "type": "enum", "role": "style", "label": "Smear", "description": "Scales the radial motion blur each camera move carries, from none to a heavy streak.", "default": "standard", "options": [{ "value": "off", "label": "Off" }, { "value": "subtle", "label": "Subtle" }, { "value": "standard", "label": "Standard" }, { "value": "heavy", "label": "Heavy" }] }
          ]'
        >
          <style>
            [data-composition-id="caption-camera-follow"] {
              --cf-accent: #ffd84d;
              --ink: #ffffff;
              position: absolute;
              inset: 0;
              overflow: hidden;
              background: transparent;
              pointer-events: none;
            }
            #cf-stage {
              position: absolute;
              inset: 0;
              overflow: hidden;
            }
            #cf-world {
              position: absolute;
              left: 0;
              top: 0;
              width: 0;
              height: 0;
              --amt: 0px;
            }
            .cf-word {
              position: absolute;
              white-space: nowrap;
              font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
              font-weight: 700;
              text-transform: uppercase;
              letter-spacing: 0.005em;
              line-height: 0.78;
              color: var(--ink);
              opacity: 0;
              --k: 0;
              filter: blur(calc(var(--k) * var(--amt)));
            }
            .cf-word.is-accent {
              color: var(--cf-accent);
            }
            #cf-vignette {
              position: absolute;
              inset: 0;
              background: radial-gradient(
                ellipse at 50% 50%,
                rgba(0, 0, 0, 0) 42%,
                rgba(0, 0, 0, 0.55) 100%
              );
            }
          </style>

          <div id="cf-stage">
            <div id="cf-world"></div>
          </div>
          <div id="cf-vignette"></div>

          <script src="https://cdn.jsdelivr.net/npm/gsap@3.14.2/dist/gsap.min.js"></script>
          <script>
            (function () {
              gsap.defaults({ immediateRender: false });

              /* Cubic bezier solver. Newton first, bisection as the fallback, so it is
                 exact and deterministic for every input. */
              function bezier(x1, y1, x2, y2) {
                function curve(t, a1, a2) {
                  var A = 1 - 3 * a2 + 3 * a1;
                  var B = 3 * a2 - 6 * a1;
                  var C = 3 * a1;
                  return ((A * t + B) * t + C) * t;
                }
                function slope(t, a1, a2) {
                  var A = 1 - 3 * a2 + 3 * a1;
                  var B = 3 * a2 - 6 * a1;
                  var C = 3 * a1;
                  return (3 * A * t + 2 * B) * t + C;
                }
                return function (p) {
                  if (p <= 0) return 0;
                  if (p >= 1) return 1;
                  var t = p;
                  for (var i = 0; i < 8; i++) {
                    var d = slope(t, x1, x2);
                    if (Math.abs(d) < 1e-6) break;
                    var e = curve(t, x1, x2) - p;
                    if (Math.abs(e) < 1e-7) return curve(t, y1, y2);
                    t -= e / d;
                  }
                  var lo = 0;
                  var hi = 1;
                  t = p;
                  for (var j = 0; j < 24; j++) {
                    var x = curve(t, x1, x2);
                    if (Math.abs(x - p) < 1e-7) break;
                    if (x > p) hi = t;
                    else lo = t;
                    t = (lo + hi) / 2;
                  }
                  return curve(t, y1, y2);
                };
              }

              /* Leaves the mark fast, spends most of its time arriving. */
              var EASE_STEP = bezier(0.31, 0, 0.11, 1);
              /* The closing pull back: slower to leave, glides a long way out. */
              var EASE_WIDE = bezier(0.42, 0, 0.14, 1);
              /* Word ink coming up. */
              var EASE_INK = bezier(0.2, 0.7, 0.3, 1);
              /* Blur rising into the move and wiped off out of it. */
              var EASE_BLUR_UP = bezier(0.2, 0.8, 0.4, 1);
              var EASE_BLUR_DOWN = bezier(0.5, 0, 0.2, 1);

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

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

              var ACCENTS = {
                gold: "#ffd84d",
                green: "#34d399",
                blue: "#38bdf8",
                violet: "#a78bfa",
              };
              /* Framing scales the margin every camera pose is fitted with, so one
                 number moves the whole shot in or out without touching cadence. */
              var FRAMINGS = { tight: 0.82, standard: 1, wide: 1.25 };
              var SMEARS = { off: 0, subtle: 0.5, standard: 1, heavy: 1.9 };

              var ACCENT = ACCENTS[pick(ACCENTS, vars.accent, "gold")];
              var FRAMING = FRAMINGS[pick(FRAMINGS, vars.framing, "standard")];
              var SMEAR = SMEARS[pick(SMEARS, vars.smear, "standard")];

              var DUR = 9;
              var STEP = 0.52;
              var MOVE = 0.4;

              var WORDS = [
                { text: "write" },
                { text: "the" },
                { text: "html", accent: true },
                { text: "and" },
                { text: "the" },
                { text: "video", accent: true },
                { text: "renders" },
                { text: "itself" },
                { text: "no" },
                { text: "timeline" },
                { text: "no" },
                { text: "keyframes", accent: true },
                { text: "just" },
                { text: "code", accent: true },
              ];

              var world = document.getElementById("cf-world");
              var stage = document.getElementById("cf-stage");
              /* The runtime strips the root id on clone, so reach the root through a
                 descendant instead of getElementById. */
              var root = stage.parentElement;
              var FRAME_W = root.clientWidth || 1080;
              var FRAME_H = root.clientHeight || 1920;
              root.style.setProperty("--cf-accent", ACCENT);

              /* Base size is picked so the opening shot sits near 1:1. Everything after it
                 is a pull back, so the world is only ever scaled down and type stays crisp. */
              var BASE = Math.max(FRAME_W, FRAME_H) * 0.16;
              /* Each new word is this fraction of the current box height. */
              var RATIO = 0.72;
              var MARGIN = 1.36 * FRAMING;

              var ruler = document.createElement("div");
              ruler.style.cssText =
                "position:absolute;left:-99999px;top:0;white-space:nowrap;visibility:hidden;" +
                'font-family:"Helvetica Neue",Helvetica,Arial,sans-serif;font-weight:700;' +
                "text-transform:uppercase;letter-spacing:0.005em;line-height:0.78";
              world.appendChild(ruler);

              var box = null;
              WORDS.forEach(function (wd, i) {
                var fs = i === 0 ? BASE : (box.y1 - box.y0) * RATIO;
                ruler.style.fontSize = fs + "px";
                ruler.textContent = wd.text;
                var w = ruler.getBoundingClientRect().width;
                var h = fs * 0.78;
                var gap = fs * 0.07;

                var x, y;
                if (i === 0) {
                  x = 0;
                  y = 0;
                } else if ((box.x1 - box.x0) / (box.y1 - box.y0) < FRAME_W / FRAME_H) {
                  /* block is narrower than the frame, so grow sideways: to the right of
                     everything, sitting on the same baseline */
                  x = box.x1 + gap;
                  y = box.y1 - h;
                } else {
                  /* block is already wide enough, so grow downward: onto a new line under
                     everything, left edges aligned */
                  x = box.x0;
                  y = box.y1 + gap;
                }

                wd.fs = fs;
                wd.x = x;
                wd.y = y;

                box = box
                  ? {
                      x0: Math.min(box.x0, x),
                      y0: Math.min(box.y0, y),
                      x1: Math.max(box.x1, x + w),
                      y1: Math.max(box.y1, y + h),
                    }
                  : { x0: x, y0: y, x1: x + w, y1: y + h };
                wd.box = { x0: box.x0, y0: box.y0, x1: box.x1, y1: box.y1 };
              });
              world.removeChild(ruler);

              var FULL = box;

              function poseFor(b, margin) {
                var bw = (b.x1 - b.x0) * margin;
                var bh = (b.y1 - b.y0) * margin;
                var s = Math.min(FRAME_W / bw, FRAME_H / bh);
                return {
                  x: FRAME_W / 2 - (s * (b.x0 + b.x1)) / 2,
                  y: FRAME_H / 2 - (s * (b.y0 + b.y1)) / 2,
                  scale: s,
                };
              }

              var els = WORDS.map(function (wd) {
                var el = document.createElement("div");
                el.className = "cf-word" + (wd.accent ? " is-accent" : "");
                el.textContent = wd.text;
                el.style.left = wd.x + "px";
                el.style.top = wd.y + "px";
                el.style.fontSize = wd.fs + "px";
                world.appendChild(el);
                return el;
              });

              /* Re-derive every framing box from what the browser actually laid out, so
                 the camera is fitted to real ink and never to arithmetic that drifted. */
              var run = null;
              els.forEach(function (el, i) {
                var r = {
                  x0: el.offsetLeft,
                  y0: el.offsetTop,
                  x1: el.offsetLeft + el.offsetWidth,
                  y1: el.offsetTop + el.offsetHeight,
                };
                run = run
                  ? {
                      x0: Math.min(run.x0, r.x0),
                      y0: Math.min(run.y0, r.y0),
                      x1: Math.max(run.x1, r.x1),
                      y1: Math.max(run.y1, r.y1),
                    }
                  : r;
                WORDS[i].box = { x0: run.x0, y0: run.y0, x1: run.x1, y1: run.y1 };
              });
              FULL = run;

              /* Rest state is pinned outside the timeline. */
              var first = poseFor(WORDS[0].box, MARGIN);
              gsap.set(world, {
                transformOrigin: "0 0",
                x: first.x,
                y: first.y,
                scale: first.scale,
              });
              gsap.set(els, { opacity: 0, "--k": 0 });
              gsap.set(world, { "--amt": "0px" });
              /* The first word is already on the page when the shot opens, so frame zero
                 is never empty. */
              gsap.set(els[0], { opacity: 1 });

              var tl = gsap.timeline({ paused: true });
              /* Peak smear at the rim of the frame, in screen pixels. */
              var BLUR = FRAME_W * 0.026 * SMEAR;
              var HALF_DIAG = Math.sqrt(FRAME_W * FRAME_W + FRAME_H * FRAME_H) / 2;

              /* Radial blur, the way a real zoom smears: a point far from the centre of
                 the move sweeps across more of the frame than one sitting on it, so it
                 streaks more. Each word gets its own share, --k, of one shared amount,
                 --amt, which is the only thing that animates. The share is fixed for the
                 length of a move and set with the camera, so this stays one tween per
                 move rather than one per word per move. --amt is authored in world units,
                 because a filter on a scaled child is applied before the scale, so the
                 screen blur has to be divided back out by the camera scale. */
              function smear(centre, scale, count, at, up, down, peak) {
                for (var j = 0; j < count; j++) {
                  var el = els[j];
                  var cx = el.offsetLeft + el.offsetWidth / 2;
                  var cy = el.offsetTop + el.offsetHeight / 2;
                  var d =
                    (scale *
                      Math.sqrt(
                        (cx - centre.x) * (cx - centre.x) + (cy - centre.y) * (cy - centre.y),
                      )) /
                    HALF_DIAG;
                  tl.set(el, { "--k": (0.2 + 1.15 * Math.min(1, d)).toFixed(3) }, at);
                }
                var amt = peak / scale;
                tl.fromTo(
                  world,
                  { "--amt": "0px" },
                  { "--amt": amt + "px", duration: up, ease: EASE_BLUR_UP },
                  at,
                );
                tl.to(world, { "--amt": "0px", duration: down, ease: EASE_BLUR_DOWN }, at + up);
              }

              WORDS.forEach(function (wd, i) {
                var t = i * STEP;
                if (i === 0) return;

                tl.fromTo(els[i], { opacity: 0 }, { opacity: 1, duration: 0.16, ease: EASE_INK }, t);

                var p = poseFor(wd.box, MARGIN);
                tl.to(world, { x: p.x, y: p.y, scale: p.scale, duration: MOVE, ease: EASE_STEP }, t);

                smear(
                  { x: (wd.box.x0 + wd.box.x1) / 2, y: (wd.box.y0 + wd.box.y1) / 2 },
                  p.scale,
                  i + 1,
                  t,
                  MOVE * 0.24,
                  MOVE * 0.44,
                  BLUR,
                );
              });

              /* The resolve: the same pull back, carried all the way out. */
              var wide = poseFor(FULL, 1.2 * FRAMING);
              var wideAt = (WORDS.length - 1) * STEP + 0.62;
              tl.to(
                world,
                {
                  x: wide.x,
                  y: wide.y,
                  scale: wide.scale,
                  duration: 0.94,
                  ease: EASE_WIDE,
                },
                wideAt,
              );
              smear(
                { x: (FULL.x0 + FULL.x1) / 2, y: (FULL.y0 + FULL.y1) / 2 },
                wide.scale,
                els.length,
                wideAt,
                0.3,
                0.58,
                BLUR * 0.8,
              );

              tl.set({}, {}, DUR);
              tl.seek(0);

              window.__timelines = window.__timelines || {};
              window.__timelines["caption-camera-follow"] = tl;
            })();
          </script>
        </div>
      </template>
    </body>
  </html>
  ```
</Accordion>

Tagged `captions` `caption-style` `camera` `typography` `motion-primitive` `portrait`.

## Related topics

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


## Related topics

- [Caption styles](/prompting/captions-catalog.md)
- [Instagram Follow](/catalog/blocks/instagram-follow.md)
- [X Follow Card](/catalog/components/x-follow-card.md)
