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hyperframes/docs/catalog/components/cursor-glyph-trail.mdx
T
Miguel ÁngelandMiguel Angel Simon Sierra 1ae2067b8d feat(catalog): put the variables panel back, on payloads (#3199) 
* feat(catalog): put the variables panel back, on payloads

The panel drove its preview by loading an .html from docs/public, a type the
host does not publish, so it showed an empty frame in production and was
parked when the catalog was re-landed.

It now mounts the same JSON payload the plain player uses and re-mounts it as
values change, injecting them as window.__hfVariables into the composition head
before any of its scripts run, which is where the runtime reads overrides from.
Doing it in the markup rather than after load is what stops the composition
initialising with the wrong values first.

172 items with variables get the panel back; the playhead carries across a
change so a tweak mid-shot does not jump back to frame zero.

* fix(docs): drop the unused url form and the needless escapes

* fix(docs): the panel cannot reference a binding beside the export

* feat(catalog): make importing an SVG the obvious move

A reader arrives at this control with a shape, not with path data, and the
panel asked for the coordinates first. Import is now the primary action in a
drop target you can see is a drop target, and the raw path sits behind a
disclosure for anyone who wants it.

* feat(cli): let a fruitless catalog search report the gap

An agent that searches by meaning and finds nothing worth installing knows
something we do not: the name of a move the catalog is missing. There was no
way to tell us, so that knowledge was lost at the end of every run.

hyperframes feedback --search-miss "<query>" --wanted "<the move>" records it.
It carries no rating, so it never lands in the rating metric, and it is a
separate deliberate command rather than something catalog --query does on its
own: plain search still sends nothing, which is what the CLI promises.

--rating stops being required at the arg level, since a miss has no rating to
give. The check moved into the run body, where an absent one is now handled
rather than crashing on undefined.

* feat(cli): carry tuned variable values into the install snippet

Someone who tunes a block on its catalog page had no way to keep those values:
the install command was the same one everybody gets, and the tuning stayed on
the page.

hyperframes add <item> --vars '<json>' now prints a mount element carrying
data-variable-values, so the values land where the block is used.

They ride on the host rather than being written into the installed file. That
keeps the composition on disk byte-identical to the registry's, so a later
reinstall can still tell an edit from an update, and it lets two mounts of the
same block carry different values.

* fix(catalog): serve the item's own directory so runtime paths resolve

Some compositions assemble their asset URLs at run time —
"compositions/components/" + texture + ".png" for the texture masks, a font the
compiler pulled into _remote_media — and no scan of the markup can see a string
that does not exist until a script concatenates it. Those items either rendered
black or were dropped to a video that had never been uploaded.

Each item that needs it now has its prepared directory published, and its
payload carries a <base> pointing at it, so any relative path the composition
invents resolves. caption-texture renders its masks again, and
variable-font-flex has a preview at all for the first time: its MP4 and poster
are both 403.

Both layouts are published, because which one a composition asks for differs
per item, and a directory only earns that if it is under 2 MB. The 12 MB
texture sheet keeps the recorded video it already had.

* fix(catalog): let the variables panel actually drive the composition

Every control on the panel was inert. The values reached the composition and
nothing repainted, because the payload had already been compiled: compiling
inlines a mounted component and resolves its variables into the markup and CSS,
so by the time a reader turns a knob there is nothing left to change.

An item that declares variables now ships uncompiled, keeping the mount the
runtime loads at run time, which is the only state where data-variable-values
still means anything. The component travels inline as a data URI rather than a
sibling file, because .html is the one type the docs host will not publish. The
demo's own pinned values come off, so the reader's choices reach the mount
instead of losing to the values the demo picked to show itself off.

Measured on the rendered frame rather than the DOM: green rgb(98,207,144),
blue rgb(6,6,199), violet rgb(177,147,230), and back to green.

docs/public/catalog drops from 48 MB to 35 MB along the way, since an
uncompiled payload carries far less than an inlined one.

* feat(catalog): keep variable changes in the url

A reader who tuned a piece lost it on reload, and had nothing to send anyone.
The values now live in the query string, scoped by composition id so two links
never read each other,and only the ones that differ from the defaults are
written, so changing one knob gives a short URL rather than every variable
spelled out.

replaceState rather than pushState: dragging a slider should not leave a trail
of history entries. An unreadable value is ignored rather than thrown, so a
truncated or hand-edited link opens the piece at its defaults.

* fix(catalog): only rewrite the url when a value actually changed

* refactor(catalog): memoise the declared defaults on their content

* feat(catalog): offer an install command carrying the tuned values

The Install block is generated before anyone touches a knob, so it can only
ever print the plain command. Someone who spent a minute tuning a piece copied
it and got the defaults back.

The panel now carries its own command in the Snippet tab, with --vars holding
exactly the values that differ. An untouched piece still offers the same short
command, so nothing gets noisier for the common case.

* fix(catalog): a piece with nothing to render is a skip, not a failure

caption-blend-difference is a stylesheet and a paragraph of prose — a class you
add to your own captions, with no standalone scene to show. The generator
treated that as a build failure, so every run ended by reporting something
broken when nothing was.

It now reports the shape it is and keeps its recorded video, which is the only
honest preview such an item has. A genuine render failure still throws.

* fix(catalog): restore variables from the url on a cold load

A shared link opened at the defaults. The first render happens on the server,
where there is no window to read the query string from, and React then hydrates
against that markup and never revisits it — so the values only appeared once you
touched a control.

The URL is read again after mount, which is the first moment it exists. The
value is also escaped once now rather than twice: URLSearchParams already
decodes on the way out, and decoding a second time turned an SVG path full of
percent-escapes into something that no longer parsed, besides doubling the
length of every link.

* fix(catalog): mount the preview with the values a link carried

The frame was built from the declared defaults and the shared values were
posted to it afterwards, which is too late for anything the composition reads
once at init: a path arrived after the mark had already been drawn from the
default one, so a link looked right in the panel and wrong on screen.

* feat(catalog): the install command follows the values you tuned

Copying the Install line gave the plain command back, because that block is
generated before anyone touches a knob and had no way to know what changed. The
tuned command only existed in the panel Snippet tab, which is not where anyone
looks for it.

The line now reads the same query string the panel writes, so the two agree
without either component knowing the other exists, and a shared link carries the
right command too. replaceState fires no event, so the panel announces its own
writes.

* fix(catalog): send a text variable to the preview once it is finished

Every other control in the explorer reports a whole value on every event: a
slider at any position is a position, a swatch is a colour. A text field is
not. Typing v3 into a badge posted v first, so the preview remounted and
rendered a composition built from half a word.

The post now waits while a text field has focus and goes out when the edit is
committed, with Enter or by clicking away. The field itself is unchanged and
still tracks every keystroke.

---------

Co-authored-by: Miguel Angel Simon Sierra <miguelangelsi07@gmail.com>
2026-08-10 22:40:01 -04:00

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---
title: "Cursor Glyph Trail"
description: "An actor travels an authored path depositing small dithered glyphs at its past positions, each popping in and decaying in place, stamp rate scaling with the actor's velocity."
---
import { InstallCommand } from "/snippets/install-command.jsx";
import { VariablesExplorer } from "/snippets/variables-explorer.jsx";
<VariablesExplorer
previewSrc="/public/catalog/components/cursor-glyph-trail.json"
compositionId="cursor-glyph-trail"
compositionSrc="compositions/components/cursor-glyph-trail.html"
variables={[{"id":"glyphs","type":"string","role":"content","label":"Glyphs","description":"Stamp charset; one glyph per stamp is chosen deterministically.","default":"░▒▓+·×"},{"id":"density","type":"enum","role":"style","label":"Density","description":"Arc-length spacing between stamps along the path.","default":"med","options":[{"value":"low","label":"Low"},{"value":"med","label":"Medium"},{"value":"high","label":"High"}]},{"id":"path","type":"enum","role":"timing","label":"Path","description":"Authored travel path preset.","default":"sweep","options":[{"value":"sweep","label":"Sweep"},{"value":"arc","label":"Arc"},{"value":"zigzag","label":"Zigzag"}]},{"id":"fade","type":"number","role":"timing","label":"Fade","description":"Per-stamp decay window in seconds, clamped 0.3 to 1.5.","default":0.8},{"id":"accent","type":"enum","role":"style","label":"Accent","description":"Trail and actor color: green rides --brand, blue rides --accent, violet rides --accent-2.","default":"green","options":[{"value":"green","label":"Green"},{"value":"blue","label":"Blue"},{"value":"violet","label":"Violet"}]},{"id":"exit","type":"enum","role":"timing","label":"Exit","description":"Optional departure. Default none: the settled actor holds until the frame cuts.","default":"none","options":[{"value":"none","label":"None"},{"value":"fade","label":"Fade"},{"value":"up","label":"Up"}]}]}
>
```html cursor-glyph-trail.html
<!doctype html>
<!--
cursor-glyph-trail: HyperFrames video primitive (product demo / trails)
An actor (default: a cursor dot) travels an authored path and deposits
small dithered glyphs at its past positions. Each glyph pops in where the
actor passed and decays in place; stamps land at fixed arc-length spacing,
so the per-second stamp rate scales with the actor's velocity. The jh3yy
stamp-and-decay register: the trail is the residue of the motion, and it
has fully dissolved before the hold.
The actor is a SLOT. Callers supply content by placing an inert template
anywhere in the HOST page (templates never render, and the runtime wipes
the host clip's own children on mount, so the slot lives at document
level):
<template data-slot="cursor-glyph-trail-actor"> ... </template>
With no slot, the primitive renders a token cursor dot (accent core,
hairline ring).
Variables (declared in data-composition-variables below):
- glyphs (string): the stamp charset; one glyph is chosen per stamp by
a fixed-seed LCG. Default is a dithered block-and-punctuation set.
- density ("low" | "med" | "high", default "med"): arc-length spacing
between stamps; higher density means tighter spacing.
- path ("sweep" | "arc" | "zigzag", default "sweep"): the authored
travel path preset.
- fade (number seconds, default 0.8, clamped 0.3 to 1.5): the decay
window of each stamp; per-stamp decay varies 0.75x to 1.25x of it.
- accent ("green" | "blue" | "violet", default "green"): green rides
--brand, blue rides --accent, violet rides --accent-2.
- exit ("none" | "fade" | "up", default "none"): frame roots own
transitions; the default holds the final frame to the last pixel.
Envelope, fixed IN and OUT with elastic HOLD only (never timeScale):
IN_BASE = TRAVEL (2.4s) + pop (0.07s) + fade * 1.25 + 0.05s margin;
the actor arrives at TRAVEL and every stamp's decay tween
ends inside IN, so the HOLD is truly still
HOLD = max(0, D - IN - OUT)
OUT_BASE = 0.45s only when exit != none
If D < IN_BASE + OUT_BASE, the whole envelope compresses together.
Determinism: the stamp table (positions, times, glyph choices, jitter,
sizes, peaks, decay multipliers) is computed exactly once during
synchronous mount from fixed LCG seed 0x67117a11. On every timeline
update, each stamp's opacity is recomputed as a pure function
f(tl.time() - t_i) of its table row, and the actor's position as a pure
function of tl.time(); stamps deliberately carry NO tweens (two
sequential tweens on one property render in direction-dependent order
under GSAP seeks, which breaks byte-identical frames). No Math.random
at runtime, no wall clock, no incremental state, no
requestAnimationFrame. Eventful seeks (suppressEvents=false, the
engine's render path) land identical frames in any order and either
direction.
Mount contract: the runtime clones only this template. #root fills the
host box (no data-width/data-height, container-type: size, cqmin units),
is styled via #root only, and registers one paused timeline under the
LITERAL "cursor-glyph-trail" key.
-->
<html
lang="en"
data-composition-id="cursor-glyph-trail"
data-composition-duration="4"
data-composition-variables='[
{ "id": "glyphs", "type": "string", "role": "content", "label": "Glyphs", "description": "Stamp charset; one glyph per stamp is chosen deterministically.", "default": "░▒▓+·×" },
{ "id": "density", "type": "enum", "role": "style", "label": "Density", "description": "Arc-length spacing between stamps along the path.", "default": "med", "options": [{ "value": "low", "label": "Low" }, { "value": "med", "label": "Medium" }, { "value": "high", "label": "High" }] },
{ "id": "path", "type": "enum", "role": "timing", "label": "Path", "description": "Authored travel path preset.", "default": "sweep", "options": [{ "value": "sweep", "label": "Sweep" }, { "value": "arc", "label": "Arc" }, { "value": "zigzag", "label": "Zigzag" }] },
{ "id": "fade", "type": "number", "role": "timing", "label": "Fade", "description": "Per-stamp decay window in seconds, clamped 0.3 to 1.5.", "default": 0.8 },
{ "id": "accent", "type": "enum", "role": "style", "label": "Accent", "description": "Trail and actor color: green rides --brand, blue rides --accent, violet rides --accent-2.", "default": "green", "options": [{ "value": "green", "label": "Green" }, { "value": "blue", "label": "Blue" }, { "value": "violet", "label": "Violet" }] },
{ "id": "exit", "type": "enum", "role": "timing", "label": "Exit", "description": "Optional departure. Default none: the settled actor holds until the frame cuts.", "default": "none", "options": [{ "value": "none", "label": "None" }, { "value": "fade", "label": "Fade" }, { "value": "up", "label": "Up" }] }
]'
>
<head>
<meta charset="UTF-8" />
<title>Cursor Glyph Trail</title>
</head>
<body>
<template>
<div id="root" data-composition-id="cursor-glyph-trail" data-duration="4" data-fps="30">
<style>
*,
*::before,
*::after {
box-sizing: border-box;
}
#root {
position: absolute;
inset: 0;
overflow: hidden;
container-type: size;
isolation: isolate;
color: var(--fg, #f8fafc);
font-family: var(--font-mono, ui-monospace, "SF Mono", Menlo, Consolas, monospace);
pointer-events: none;
}
.cgt-clip {
position: absolute;
inset: 0;
overflow: hidden;
background: var(--bg, transparent);
}
.cgt-stage {
position: absolute;
inset: 0;
will-change: transform, opacity;
}
.cgt-field {
position: absolute;
inset: 0;
}
.cgt-stamp {
position: absolute;
opacity: 0;
line-height: 1;
font-weight: 500;
will-change: opacity;
user-select: none;
}
.cgt-actor {
position: absolute;
opacity: 0;
transform: translate(-50%, -50%);
will-change: opacity;
}
.cgt-dot {
width: 3.4cqmin;
height: 3.4cqmin;
border-radius: 50%;
background: var(--cgt-accent);
border: 0.35cqmin solid color-mix(in srgb, var(--fg, #f8fafc) 82%, var(--cgt-accent));
box-shadow: 0 0.6cqmin 2.4cqmin color-mix(in srgb, var(--bg, #000000) 35%, transparent);
}
</style>
<div
id="cursor-glyph-trail-clip"
class="cgt-clip clip"
data-start="0"
data-duration="4"
data-track-index="0"
>
<div class="cgt-stage">
<div class="cgt-field" aria-hidden="true"></div>
<div class="cgt-actor">
<div class="cgt-dot"></div>
</div>
</div>
</div>
<script src="https://cdn.jsdelivr.net/npm/gsap@3.14.2/dist/gsap.min.js"></script>
<script>
(function () {
"use strict";
var root = document.getElementById("root");
var stage = root.querySelector(".cgt-stage");
var field = root.querySelector(".cgt-field");
var actor = root.querySelector(".cgt-actor");
var vars =
window.__hyperframes && window.__hyperframes.getVariables
? window.__hyperframes.getVariables()
: {};
// Arc-length spacing (percent-of-stage units). Fixed spacing
// along the path means the per-second stamp rate rises and
// falls with the actor's velocity: the density law.
var spacingByDensity = { low: 4.6, med: 2.9, high: 1.8 };
var density = Object.prototype.hasOwnProperty.call(spacingByDensity, vars.density)
? vars.density
: "med";
var pathName = vars.path === "arc" || vars.path === "zigzag" ? vars.path : "sweep";
var glyphSource =
typeof vars.glyphs === "string" && vars.glyphs.length > 0 ? vars.glyphs : "░▒▓+·×";
var glyphSet = Array.from(glyphSource);
var fadeRaw = parseFloat(vars.fade);
var fade = isFinite(fadeRaw) ? Math.min(1.5, Math.max(0.3, fadeRaw)) : 0.8;
// Each enum choice routes to a DIFFERENT contract token so the
// variable stays meaningful under a theme.
var accentColors = {
green: "var(--brand, #52525b)",
blue: "var(--accent, #52525b)",
violet: "var(--accent-2, #52525b)",
};
var accent = Object.prototype.hasOwnProperty.call(accentColors, vars.accent)
? vars.accent
: "green";
var exit = vars.exit === "fade" || vars.exit === "up" ? vars.exit : "none";
root.style.setProperty("--cgt-accent", accentColors[accent]);
// SLOT. Caller templates live at HOST DOCUMENT level (the mount
// wipes host-clip children, and templates never render).
var hostDoc = root.ownerDocument;
var slotTemplate = null;
try {
slotTemplate = hostDoc.querySelector(
'template[data-slot="cursor-glyph-trail-actor"]',
);
} catch (error) {
slotTemplate = null;
}
if (slotTemplate) {
actor.querySelector(".cgt-dot").remove();
actor.appendChild(hostDoc.importNode(slotTemplate.content, true));
}
// Envelope: fixed IN/OUT, elastic HOLD, never time-scaled.
var POP = 0.07;
var TRAVEL_BASE = 2.4;
var IN_BASE = TRAVEL_BASE + POP + fade * 1.25 + 0.05;
var OUT_BASE = exit === "none" ? 0 : 0.45;
var duration = Math.max(0.001, parseFloat(root.dataset.duration || "4"));
var totalBase = Math.max(0.001, IN_BASE + OUT_BASE);
var scale = duration < totalBase ? duration / totalBase : 1;
var TRAVEL = TRAVEL_BASE * scale;
var pop = POP * scale;
var fadeEff = fade * scale;
var IN = IN_BASE * scale;
var OUT = OUT_BASE * scale;
var HOLD = Math.max(0, duration - (IN + OUT));
var OUT_START = IN + HOLD;
// Path presets in percent-of-stage coordinates.
var zigzagPoints = [
{ x: 10, y: 34 },
{ x: 38, y: 70 },
{ x: 64, y: 32 },
{ x: 90, y: 64 },
];
function pathPoint(u) {
if (pathName === "arc") {
return { x: 12 + 76 * u, y: 68 - 40 * Math.sin(Math.PI * u) };
}
if (pathName === "zigzag") {
var segs = zigzagPoints.length - 1;
var s = Math.min(segs - 1e-9, Math.max(0, u * segs));
var i = Math.floor(s);
var f = s - i;
var a = zigzagPoints[i];
var b = zigzagPoints[i + 1];
return { x: a.x + (b.x - a.x) * f, y: a.y + (b.y - a.y) * f };
}
// sweep: an S-curve from lower left to upper right.
return { x: 8 + 84 * u, y: 50 + 16 * Math.cos(Math.PI * u) };
}
// Shared travel ease, implemented once so the stamp table and
// the per-update actor position use the identical mapping.
function easeInOut(t) {
return t < 0.5 ? 2 * t * t : 1 - 2 * (1 - t) * (1 - t);
}
function clamp01(v) {
return v < 0 ? 0 : v > 1 ? 1 : v;
}
// The LCG and every per-stamp decision live here, computed once
// before timeline construction from a fixed seed. A stamp's
// opacity at any time is then a pure function of timeline time.
var lcgState = 0x67117a11;
function next() {
lcgState = (Math.imul(1664525, lcgState) + 1013904223) >>> 0;
return lcgState / 4294967296;
}
var spacing = spacingByDensity[density];
var STEPS = 600;
var stamps = [];
var acc = 0;
var prev = pathPoint(easeInOut(0));
for (var k = 1; k <= STEPS; k += 1) {
var f = k / STEPS;
var pos = pathPoint(easeInOut(f));
acc += Math.hypot(pos.x - prev.x, pos.y - prev.y);
prev = pos;
if (acc >= spacing) {
acc -= spacing;
stamps.push({
t: f * TRAVEL,
x: pos.x + (next() - 0.5) * 3.2,
y: pos.y + (next() - 0.5) * 3.2,
glyph: glyphSet[Math.floor(next() * glyphSet.length) % glyphSet.length],
rot: (next() - 0.5) * 20,
size: 1.9 + next() * 1.4,
peak: 0.45 + next() * 0.45,
mix: 55 + Math.floor(next() * 36),
fadeMul: 0.75 + next() * 0.5,
});
}
}
var fragment = hostDoc.createDocumentFragment();
for (var s = 0; s < stamps.length; s += 1) {
var row = stamps[s];
var span = hostDoc.createElement("span");
span.className = "cgt-stamp";
span.textContent = row.glyph;
span.style.left = row.x.toFixed(3) + "%";
span.style.top = row.y.toFixed(3) + "%";
span.style.fontSize = row.size.toFixed(3) + "cqmin";
span.style.transform = "translate(-50%, -50%) rotate(" + row.rot.toFixed(2) + "deg)";
span.style.color =
"color-mix(in srgb, var(--cgt-accent) " + row.mix + "%, var(--fg, #f8fafc))";
row.el = span;
fragment.appendChild(span);
}
field.appendChild(fragment);
// Pure per-update apply: the actor position and every stamp's
// opacity are functions of tl.time() alone. A stamp pops in
// over `pop` seconds and decays over its table row's window;
// by IN every value is exactly zero. Writes are idempotent, so
// the HOLD repaints identical values and stays truly still.
function stampOpacity(row, timeSeconds) {
var dt = timeSeconds - row.t;
if (dt <= 0) return 0;
if (dt < pop) {
var g = dt / pop;
return row.peak * (1 - (1 - g) * (1 - g));
}
var u = (dt - pop) / (fadeEff * row.fadeMul);
if (u >= 1) return 0;
return row.peak * (1 - u * u);
}
function applyTime(timeSeconds) {
var u = easeInOut(clamp01(TRAVEL > 0 ? timeSeconds / TRAVEL : 1));
var p = pathPoint(u);
gsap.set(actor, { left: p.x.toFixed(4) + "%", top: p.y.toFixed(4) + "%" });
for (var i = 0; i < stamps.length; i += 1) {
stamps[i].el.style.opacity = stampOpacity(stamps[i], timeSeconds).toFixed(4);
}
}
gsap.set(stage, { opacity: 1, y: "0cqh" });
var tl = gsap.timeline({
paused: true,
onUpdate: function () {
applyTime(tl.time());
},
});
// Anchor tween: an inert plain-object tween spanning the full
// authored duration so the timeline covers [0, D], onUpdate
// fires for every eventful seek, and holds never clamp short.
tl.to({ p: 0 }, { p: 1, duration: duration, ease: "none" }, 0);
// Actor entrance: both endpoints authored.
tl.fromTo(
actor,
{ opacity: 0 },
{ opacity: 1, duration: 0.18 * scale, ease: "power2.out" },
0,
);
// Stamps carry no tweens: their opacity rides applyTime's pure
// table evaluation, and each decay completes inside IN by
// construction.
// HOLD: truly still. All stamps are exactly zero by IN and the
// actor rests at path(1); repeated repaints write identical
// values.
// OUT: optional departure; exit none holds until the frame cuts.
if (exit === "up") {
tl.to(stage, { y: "-4cqh", duration: OUT, ease: "power2.in" }, OUT_START);
tl.to(stage, { opacity: 0, duration: OUT, ease: "power2.in" }, OUT_START);
} else if (exit === "fade") {
tl.to(stage, { opacity: 0, duration: OUT, ease: "power2.in" }, OUT_START);
}
tl.seek(0);
applyTime(0);
window.__timelines = window.__timelines || {};
window.__timelines["cursor-glyph-trail"] = tl;
})();
</script>
</div>
</template>
</body>
</html>
```
</VariablesExplorer>
## Install
<InstallCommand command="npx hyperframes add cursor-glyph-trail" item="cursor-glyph-trail" />
That writes one file: `compositions/components/cursor-glyph-trail.html`.
## Paste it into your composition
Open `compositions/components/cursor-glyph-trail.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 |
| --- | --- | --- | --- |
| `glyphs` | `░▒▓+·×` | string | Stamp charset; one glyph per stamp is chosen deterministically. |
| `density` | `med` | `low`, `med`, `high` | Arc-length spacing between stamps along the path. |
| `path` | `sweep` | `sweep`, `arc`, `zigzag` | Authored travel path preset. |
| `fade` | `0.8` | number | Per-stamp decay window in seconds, clamped 0.3 to 1.5. |
| `accent` | `green` | `green`, `blue`, `violet` | Trail and actor color: green rides --brand, blue rides --accent, violet rides --accent-2. |
| `exit` | `none` | `none`, `fade`, `up` | Optional departure. Default none: the settled actor holds until the frame cuts. |
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
<div
data-composition-id="cursor-glyph-trail"
data-composition-src="compositions/components/cursor-glyph-trail.html"
data-variable-values='{"glyphs":"░▒▓+·×","density":"med","path":"sweep","fade":0.8,"accent":"green","exit":"none"}'
></div>
```
## Source
<Accordion title={`cursor-glyph-trail.html`}>
```html
<!doctype html>
<!--
cursor-glyph-trail: HyperFrames video primitive (product demo / trails)
An actor (default: a cursor dot) travels an authored path and deposits
small dithered glyphs at its past positions. Each glyph pops in where the
actor passed and decays in place; stamps land at fixed arc-length spacing,
so the per-second stamp rate scales with the actor's velocity. The jh3yy
stamp-and-decay register: the trail is the residue of the motion, and it
has fully dissolved before the hold.
The actor is a SLOT. Callers supply content by placing an inert template
anywhere in the HOST page (templates never render, and the runtime wipes
the host clip's own children on mount, so the slot lives at document
level):
<template data-slot="cursor-glyph-trail-actor"> ... </template>
With no slot, the primitive renders a token cursor dot (accent core,
hairline ring).
Variables (declared in data-composition-variables below):
- glyphs (string): the stamp charset; one glyph is chosen per stamp by
a fixed-seed LCG. Default is a dithered block-and-punctuation set.
- density ("low" | "med" | "high", default "med"): arc-length spacing
between stamps; higher density means tighter spacing.
- path ("sweep" | "arc" | "zigzag", default "sweep"): the authored
travel path preset.
- fade (number seconds, default 0.8, clamped 0.3 to 1.5): the decay
window of each stamp; per-stamp decay varies 0.75x to 1.25x of it.
- accent ("green" | "blue" | "violet", default "green"): green rides
--brand, blue rides --accent, violet rides --accent-2.
- exit ("none" | "fade" | "up", default "none"): frame roots own
transitions; the default holds the final frame to the last pixel.
Envelope, fixed IN and OUT with elastic HOLD only (never timeScale):
IN_BASE = TRAVEL (2.4s) + pop (0.07s) + fade * 1.25 + 0.05s margin;
the actor arrives at TRAVEL and every stamp's decay tween
ends inside IN, so the HOLD is truly still
HOLD = max(0, D - IN - OUT)
OUT_BASE = 0.45s only when exit != none
If D < IN_BASE + OUT_BASE, the whole envelope compresses together.
Determinism: the stamp table (positions, times, glyph choices, jitter,
sizes, peaks, decay multipliers) is computed exactly once during
synchronous mount from fixed LCG seed 0x67117a11. On every timeline
update, each stamp's opacity is recomputed as a pure function
f(tl.time() - t_i) of its table row, and the actor's position as a pure
function of tl.time(); stamps deliberately carry NO tweens (two
sequential tweens on one property render in direction-dependent order
under GSAP seeks, which breaks byte-identical frames). No Math.random
at runtime, no wall clock, no incremental state, no
requestAnimationFrame. Eventful seeks (suppressEvents=false, the
engine's render path) land identical frames in any order and either
direction.
Mount contract: the runtime clones only this template. #root fills the
host box (no data-width/data-height, container-type: size, cqmin units),
is styled via #root only, and registers one paused timeline under the
LITERAL "cursor-glyph-trail" key.
-->
<html
lang="en"
data-composition-id="cursor-glyph-trail"
data-composition-duration="4"
data-composition-variables='[
{ "id": "glyphs", "type": "string", "role": "content", "label": "Glyphs", "description": "Stamp charset; one glyph per stamp is chosen deterministically.", "default": "░▒▓+·×" },
{ "id": "density", "type": "enum", "role": "style", "label": "Density", "description": "Arc-length spacing between stamps along the path.", "default": "med", "options": [{ "value": "low", "label": "Low" }, { "value": "med", "label": "Medium" }, { "value": "high", "label": "High" }] },
{ "id": "path", "type": "enum", "role": "timing", "label": "Path", "description": "Authored travel path preset.", "default": "sweep", "options": [{ "value": "sweep", "label": "Sweep" }, { "value": "arc", "label": "Arc" }, { "value": "zigzag", "label": "Zigzag" }] },
{ "id": "fade", "type": "number", "role": "timing", "label": "Fade", "description": "Per-stamp decay window in seconds, clamped 0.3 to 1.5.", "default": 0.8 },
{ "id": "accent", "type": "enum", "role": "style", "label": "Accent", "description": "Trail and actor color: green rides --brand, blue rides --accent, violet rides --accent-2.", "default": "green", "options": [{ "value": "green", "label": "Green" }, { "value": "blue", "label": "Blue" }, { "value": "violet", "label": "Violet" }] },
{ "id": "exit", "type": "enum", "role": "timing", "label": "Exit", "description": "Optional departure. Default none: the settled actor holds until the frame cuts.", "default": "none", "options": [{ "value": "none", "label": "None" }, { "value": "fade", "label": "Fade" }, { "value": "up", "label": "Up" }] }
]'
>
<head>
<meta charset="UTF-8" />
<title>Cursor Glyph Trail</title>
</head>
<body>
<template>
<div id="root" data-composition-id="cursor-glyph-trail" data-duration="4" data-fps="30">
<style>
*,
*::before,
*::after {
box-sizing: border-box;
}
#root {
position: absolute;
inset: 0;
overflow: hidden;
container-type: size;
isolation: isolate;
color: var(--fg, #f8fafc);
font-family: var(--font-mono, ui-monospace, "SF Mono", Menlo, Consolas, monospace);
pointer-events: none;
}
.cgt-clip {
position: absolute;
inset: 0;
overflow: hidden;
background: var(--bg, transparent);
}
.cgt-stage {
position: absolute;
inset: 0;
will-change: transform, opacity;
}
.cgt-field {
position: absolute;
inset: 0;
}
.cgt-stamp {
position: absolute;
opacity: 0;
line-height: 1;
font-weight: 500;
will-change: opacity;
user-select: none;
}
.cgt-actor {
position: absolute;
opacity: 0;
transform: translate(-50%, -50%);
will-change: opacity;
}
.cgt-dot {
width: 3.4cqmin;
height: 3.4cqmin;
border-radius: 50%;
background: var(--cgt-accent);
border: 0.35cqmin solid color-mix(in srgb, var(--fg, #f8fafc) 82%, var(--cgt-accent));
box-shadow: 0 0.6cqmin 2.4cqmin color-mix(in srgb, var(--bg, #000000) 35%, transparent);
}
</style>
<div
id="cursor-glyph-trail-clip"
class="cgt-clip clip"
data-start="0"
data-duration="4"
data-track-index="0"
>
<div class="cgt-stage">
<div class="cgt-field" aria-hidden="true"></div>
<div class="cgt-actor">
<div class="cgt-dot"></div>
</div>
</div>
</div>
<script src="https://cdn.jsdelivr.net/npm/gsap@3.14.2/dist/gsap.min.js"></script>
<script>
(function () {
"use strict";
var root = document.getElementById("root");
var stage = root.querySelector(".cgt-stage");
var field = root.querySelector(".cgt-field");
var actor = root.querySelector(".cgt-actor");
var vars =
window.__hyperframes && window.__hyperframes.getVariables
? window.__hyperframes.getVariables()
: {};
// Arc-length spacing (percent-of-stage units). Fixed spacing
// along the path means the per-second stamp rate rises and
// falls with the actor's velocity: the density law.
var spacingByDensity = { low: 4.6, med: 2.9, high: 1.8 };
var density = Object.prototype.hasOwnProperty.call(spacingByDensity, vars.density)
? vars.density
: "med";
var pathName = vars.path === "arc" || vars.path === "zigzag" ? vars.path : "sweep";
var glyphSource =
typeof vars.glyphs === "string" && vars.glyphs.length > 0 ? vars.glyphs : "░▒▓+·×";
var glyphSet = Array.from(glyphSource);
var fadeRaw = parseFloat(vars.fade);
var fade = isFinite(fadeRaw) ? Math.min(1.5, Math.max(0.3, fadeRaw)) : 0.8;
// Each enum choice routes to a DIFFERENT contract token so the
// variable stays meaningful under a theme.
var accentColors = {
green: "var(--brand, #52525b)",
blue: "var(--accent, #52525b)",
violet: "var(--accent-2, #52525b)",
};
var accent = Object.prototype.hasOwnProperty.call(accentColors, vars.accent)
? vars.accent
: "green";
var exit = vars.exit === "fade" || vars.exit === "up" ? vars.exit : "none";
root.style.setProperty("--cgt-accent", accentColors[accent]);
// SLOT. Caller templates live at HOST DOCUMENT level (the mount
// wipes host-clip children, and templates never render).
var hostDoc = root.ownerDocument;
var slotTemplate = null;
try {
slotTemplate = hostDoc.querySelector(
'template[data-slot="cursor-glyph-trail-actor"]',
);
} catch (error) {
slotTemplate = null;
}
if (slotTemplate) {
actor.querySelector(".cgt-dot").remove();
actor.appendChild(hostDoc.importNode(slotTemplate.content, true));
}
// Envelope: fixed IN/OUT, elastic HOLD, never time-scaled.
var POP = 0.07;
var TRAVEL_BASE = 2.4;
var IN_BASE = TRAVEL_BASE + POP + fade * 1.25 + 0.05;
var OUT_BASE = exit === "none" ? 0 : 0.45;
var duration = Math.max(0.001, parseFloat(root.dataset.duration || "4"));
var totalBase = Math.max(0.001, IN_BASE + OUT_BASE);
var scale = duration < totalBase ? duration / totalBase : 1;
var TRAVEL = TRAVEL_BASE * scale;
var pop = POP * scale;
var fadeEff = fade * scale;
var IN = IN_BASE * scale;
var OUT = OUT_BASE * scale;
var HOLD = Math.max(0, duration - (IN + OUT));
var OUT_START = IN + HOLD;
// Path presets in percent-of-stage coordinates.
var zigzagPoints = [
{ x: 10, y: 34 },
{ x: 38, y: 70 },
{ x: 64, y: 32 },
{ x: 90, y: 64 },
];
function pathPoint(u) {
if (pathName === "arc") {
return { x: 12 + 76 * u, y: 68 - 40 * Math.sin(Math.PI * u) };
}
if (pathName === "zigzag") {
var segs = zigzagPoints.length - 1;
var s = Math.min(segs - 1e-9, Math.max(0, u * segs));
var i = Math.floor(s);
var f = s - i;
var a = zigzagPoints[i];
var b = zigzagPoints[i + 1];
return { x: a.x + (b.x - a.x) * f, y: a.y + (b.y - a.y) * f };
}
// sweep: an S-curve from lower left to upper right.
return { x: 8 + 84 * u, y: 50 + 16 * Math.cos(Math.PI * u) };
}
// Shared travel ease, implemented once so the stamp table and
// the per-update actor position use the identical mapping.
function easeInOut(t) {
return t < 0.5 ? 2 * t * t : 1 - 2 * (1 - t) * (1 - t);
}
function clamp01(v) {
return v < 0 ? 0 : v > 1 ? 1 : v;
}
// The LCG and every per-stamp decision live here, computed once
// before timeline construction from a fixed seed. A stamp's
// opacity at any time is then a pure function of timeline time.
var lcgState = 0x67117a11;
function next() {
lcgState = (Math.imul(1664525, lcgState) + 1013904223) >>> 0;
return lcgState / 4294967296;
}
var spacing = spacingByDensity[density];
var STEPS = 600;
var stamps = [];
var acc = 0;
var prev = pathPoint(easeInOut(0));
for (var k = 1; k <= STEPS; k += 1) {
var f = k / STEPS;
var pos = pathPoint(easeInOut(f));
acc += Math.hypot(pos.x - prev.x, pos.y - prev.y);
prev = pos;
if (acc >= spacing) {
acc -= spacing;
stamps.push({
t: f * TRAVEL,
x: pos.x + (next() - 0.5) * 3.2,
y: pos.y + (next() - 0.5) * 3.2,
glyph: glyphSet[Math.floor(next() * glyphSet.length) % glyphSet.length],
rot: (next() - 0.5) * 20,
size: 1.9 + next() * 1.4,
peak: 0.45 + next() * 0.45,
mix: 55 + Math.floor(next() * 36),
fadeMul: 0.75 + next() * 0.5,
});
}
}
var fragment = hostDoc.createDocumentFragment();
for (var s = 0; s < stamps.length; s += 1) {
var row = stamps[s];
var span = hostDoc.createElement("span");
span.className = "cgt-stamp";
span.textContent = row.glyph;
span.style.left = row.x.toFixed(3) + "%";
span.style.top = row.y.toFixed(3) + "%";
span.style.fontSize = row.size.toFixed(3) + "cqmin";
span.style.transform = "translate(-50%, -50%) rotate(" + row.rot.toFixed(2) + "deg)";
span.style.color =
"color-mix(in srgb, var(--cgt-accent) " + row.mix + "%, var(--fg, #f8fafc))";
row.el = span;
fragment.appendChild(span);
}
field.appendChild(fragment);
// Pure per-update apply: the actor position and every stamp's
// opacity are functions of tl.time() alone. A stamp pops in
// over `pop` seconds and decays over its table row's window;
// by IN every value is exactly zero. Writes are idempotent, so
// the HOLD repaints identical values and stays truly still.
function stampOpacity(row, timeSeconds) {
var dt = timeSeconds - row.t;
if (dt <= 0) return 0;
if (dt < pop) {
var g = dt / pop;
return row.peak * (1 - (1 - g) * (1 - g));
}
var u = (dt - pop) / (fadeEff * row.fadeMul);
if (u >= 1) return 0;
return row.peak * (1 - u * u);
}
function applyTime(timeSeconds) {
var u = easeInOut(clamp01(TRAVEL > 0 ? timeSeconds / TRAVEL : 1));
var p = pathPoint(u);
gsap.set(actor, { left: p.x.toFixed(4) + "%", top: p.y.toFixed(4) + "%" });
for (var i = 0; i < stamps.length; i += 1) {
stamps[i].el.style.opacity = stampOpacity(stamps[i], timeSeconds).toFixed(4);
}
}
gsap.set(stage, { opacity: 1, y: "0cqh" });
var tl = gsap.timeline({
paused: true,
onUpdate: function () {
applyTime(tl.time());
},
});
// Anchor tween: an inert plain-object tween spanning the full
// authored duration so the timeline covers [0, D], onUpdate
// fires for every eventful seek, and holds never clamp short.
tl.to({ p: 0 }, { p: 1, duration: duration, ease: "none" }, 0);
// Actor entrance: both endpoints authored.
tl.fromTo(
actor,
{ opacity: 0 },
{ opacity: 1, duration: 0.18 * scale, ease: "power2.out" },
0,
);
// Stamps carry no tweens: their opacity rides applyTime's pure
// table evaluation, and each decay completes inside IN by
// construction.
// HOLD: truly still. All stamps are exactly zero by IN and the
// actor rests at path(1); repeated repaints write identical
// values.
// OUT: optional departure; exit none holds until the frame cuts.
if (exit === "up") {
tl.to(stage, { y: "-4cqh", duration: OUT, ease: "power2.in" }, OUT_START);
tl.to(stage, { opacity: 0, duration: OUT, ease: "power2.in" }, OUT_START);
} else if (exit === "fade") {
tl.to(stage, { opacity: 0, duration: OUT, ease: "power2.in" }, OUT_START);
}
tl.seek(0);
applyTime(0);
window.__timelines = window.__timelines || {};
window.__timelines["cursor-glyph-trail"] = tl;
})();
</script>
</div>
</template>
</body>
</html>
```
</Accordion>
{/* hf:generated-footer */}
Tagged `motion-primitive` `demonstrate` `trail` `cursor` `glyphs` `deterministic`.
## Related topics
- [Browse the complete Catalog](/catalog)
- [Add assets and Catalog items in Studio](/studio/assets-and-blocks)
- [Build a richer composition](/go-further)
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