Me Here 9cb7c2c193 Per-step pad grid (beats × subdivision); drop confusing Sig dropdown; help: repo link + offline note

- Pad row now shows beatsPerBar × subdivision pads, each individually
  toggleable (the subdivision control sets pad resolution). Subdivision
  pads render smaller; downbeats labeled; group/beat gaps preserved.
- Mask (beatsOn) is now per-step; playhead tracks the current step.
  recomputeLane remaps on grouping/subdivision change and migrates legacy
  per-beat masks (saved data, short share patterns) by expanding across subs.
- Share language: =pattern is now per-step (len = beats × sub); short
  per-beat patterns still accepted and expanded. README updated.
- Removed the Sig time-signature preset dropdown (confusing vs subdivision).
- Help dialog: link to git.varasys.io/VARASYS/metronome + note that it's a
  single-page app you can save & run offline, but file:// won't auto-save
  the set list (export a backup).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

2026-05-25 08:01:17 -05:00

5.4 KiB

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Stackable Metronome

A browser polymetric groove trainer / metronome — and the design mockup for a Raspberry Pi Pico hardware build. Stack as many "meter lanes" as you like; each is its own little metronome with a grouping, subdivision, drum voice and per-beat pattern. Layering lanes produces polymeter and true ratio polyrhythm.

Live: https://metronome.varasys.io

It's a single page (index.html) plus a vendored QR library — no build step, no framework. State (presets, set lists, practice log, theme) lives in localStorage.

Features

Meter lanes — grouping (odd meters), subdivision, GM drum voice, per‑beat on/off pattern (rests), mute, live measure counter.
Polyrhythm — a per‑lane poly toggle fits a lane's beats evenly into lane 1's bar (e.g. 5‑over‑4, 3‑over‑2).
Practice — gap/mute trainer (play N / mute M bars) and a tempo ramp with a start BPM and signed step.
Set lists — named, ordered lists of saved setups; ▶ loads + starts an item, N advances; each play is logged for cross‑day comparison.
Sharing — copy a link (with QR) to your current settings or a whole set list.
Theming — System / Light / Dark.

A compact, human‑readable text encodes a full configuration (a patch). It's what goes in a share link, and you can hand‑write or edit it.

Patch grammar

v1 ; t<bpm> [; vol<pct>] ; <lane> ; <lane> … [; tr<play>/<mute>] [; rmp<start>/<step>/<every>]

Token	Meaning	Example
`v1`	format version (always first)	`v1`
`t<bpm>`	tempo	`t120`
`vol<pct>`	master volume 0–100	`vol70`
`tr<play>/<mute>`	gap trainer: play N bars, mute M	`tr2/2`
`rmp<start>/<step>/<every>`	tempo ramp: start BPM, ±step, every N bars	`rmp80/5/4`
`<lane>`	a meter lane (see below)	`kick:4`

Tokens are joined with ;. tr and rmp are omitted when off.

Lane grammar

<sound> : <grouping> [ / <sub> ] [ = <pattern> ] [ ~ ] [ ! ]

sound — one of: beep, kick, snare, rim, clap, hatClosed, hatOpen, ride, crash, tomLow, tomMid, tomHigh, tambourine, cowbell, woodblock, claves, jamblock (unknown → beep).
grouping — beats per bar, optionally grouped for odd meters: 4, 3, 2+2+3. The first beat of each group is accented.
/sub — subdivision: 1 quarter (default), 2 eighth, 3 triplet, 4 sixteenth, 6 sextuplet. This also sets how many pads each beat splits into (a beat becomes sub individually‑toggleable steps). Omit for quarter.
=pattern — per‑step on/off as x/., length = beats per bar × sub (one char per pad). Omit = all on. e.g. 4=.x.x is a backbeat on 2 & 4; 4/4=x..x..x.x...x... is a sixteenth‑grid pattern. A short pattern whose length equals just the beat count is still accepted and expanded across each beat's subdivisions (back‑compat).
~ — polyrhythm: fit this lane's beats evenly into lane 1's bar.
! — mute the lane.

Examples

Patch / lane	What it is
`kick:4`	kick on 4 quarter beats
`snare:4=.x.x`	snare backbeat (2 & 4)
`hatClosed:4/2`	eighth‑note hi‑hats
`claves:5~`	5 evenly across lane 1's bar (5‑over‑4 if lane 1 is `4`)
`kick:2+2+3=x..x..x`	7/8, kick on each group start
`cowbell:3+2/2`	5/4 grouped 3+2, eighth subdivision
Full: `v1;t120;kick:4;snare:4=.x.x;hatClosed:4/2;tr2/2`	backbeat groove with gap trainer

In URLs

Settings: …/#p=<patch> — readable, e.g. …/#p=v1;t120;kick:4;claves:5~
Set list: …/#sl=<base64url> — a JSON {title, description, items[]} where each item's config is a patch string. Used because titles/notes are free text.

Opening such a link applies the settings (or imports the set list) on load, then clears the hash so a refresh won't re‑import.

In the set‑list panel's ⋯ menu:

Share settings link / Share set‑list link open a dialog with the link to Copy or Open.
QR ↗ opens a third‑party QR service (api.qrserver.com) with the link in its URL so you can scan it on a phone. A banner warns you it's external — confirm the QR decodes to the shown link before trusting it. (No QR is generated locally.)
Export all / Import file back up presets + set lists + logs as a JSON file.

Keyboard shortcuts

Key	Action
`P`	play / stop
`T`	tap tempo
`↑` / `↓`	tempo ±1 (`Shift` = ±10)
`A`	add meter lane
`1`–`9`	mute lane N
`R`	toggle the set‑list panel
`N`	next set‑list item
`?`	shortcuts help
`Esc`	close dialog / panel

Versioning

VERSION holds the formal version. deploy.sh stamps the served page:

Formal — a clean commit tagged v<VERSION> → X.Y.Z.
Dev — anything else → X.Y.Z-dev.<utc-timestamp>.<short-sha>[.dirty].

Cut a release with ./release.sh [X.Y.Z] (bumps VERSION + tags v<VERSION>), then push the tag and deploy.

Deploy

./deploy.sh copies index.html (version‑stamped) into the Caddy web root and smoke‑tests the live URL. No restart needed (file_server picks up changes immediately).

Files

File	Purpose
`index.html`	the whole app
`deploy.sh`	publish to the Caddy web root
`release.sh`	tag a formal version
`VERSION`	formal version string

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