Install
That writes one file:compositions/components/cursor-glyph-trail.html.
Paste it into your composition
Opencompositions/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. |
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:
<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
cursor-glyph-trail.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>
motion-primitive demonstrate trail cursor glyphs deterministic.