The instruments

Eight layouts came with 1.0; five more make the sheet an instrument’s geometry rather than a keyboard’s. All thirteen are in the picker on every platform, and the eight keyed ones are playable on the tablets. Two of the five are stateful: where a note lands depends on a fingering the engine holds — the valves or the slide — so the same MIDI note is a different cell under a different fingering. The other three are pure functions of the note, like the first eight.

The trumpet and the trombone

The trumpet is eight cells, one per partial of a B♭ instrument’s harmonic series — the pedal B♭1 at the bottom, then B♭2, F3, B♭3, D4, F4, A♭4, B♭4 — and each cell sounds its partial minus the valves’ offset: valve 1 lowers by a whole tone, valve 2 by a semitone, valve 3 by a minor third, and they add. The trombone is seven partial cells and a slide that lowers continuously, up to six semitones. The fingering is MIDI, global, on the master channel: valves CC 110, 111 and 112 (≥ 64 is pressed), the slide CC 113 (0 is closed, 127 is the seventh position), smoothed over 10 ms; a controller that sends them plays the layouts exactly as the tablets do. A note arriving from the wire lands in the partial the current fingering selects; if none does, the standard fingering’s; else the nearest partial.

Each cell’s lip bend axis runs to the right: a bend of one semitone moves the drop one cell radius, the brass player’s lipping. The partials sit in a column by default or, with Partials on an arc, on a ring — radius 0.30 canvas heights, centred a little right of the middle at 0.65 of the height, cells of 0.055 — cut by the author’s eye on the iPad; the trombone’s seven sit on the same ring under the one flag. Both geometries are in the gates bitwise.

On a tablet the fingering panel holds the three valve pads (or the slide) large, at the side at mid-height, or horizontal along the bottom — the toggle lives under the brass layouts in the settings and on the panel’s rotate button — with the control strip at the opposite corner, clear of the settings gear. Press a valve and every held voice retunes — ramped over 30 ms for the valves, at once for the slide — through a bend on its member channel, so a DAW records the lipping and the fingering as one MPE voice; a touch that lands while the valves change begins between semitones and resolves on its first retune. The engine’s own fingering copy is what the panel mirrors: the probe is asked with the state the shell sent, so the overlay and the hit-test agree with the water.

Under Suzu the Trumpet patch sounds the fingering it is given and CC 74 is the embouchure; the Bowed string holds under the valves as a brass note holds under the lips.

Wicki–Hayden

A hex button-field six buttons wide and fifteen rows tall, on which every note has exactly one button: a step right is a whole tone, up-right a fifth, up-left a fourth, the octave two rows straight up — the Hayden duet concertina’s field. The rows alternate the two whole-tone scales and sit half a button apart. Pitch is a plane over the sheet, so the bend axis is that plane’s gradient: a bend moves the drop up the field toward the higher notes, whatever the row.

Strings

String rows across chromatic frets under one of three fixed tunings — Standard guitar (E2 A2 D3 G3 B3 E4), Whole-tone tap (twelve strings a whole tone apart, E2 to D4, the tapping grid’s isomorphism) and All fourths — chosen with Tuning under the layout. A note is stamped at its lowest-fret site on every string that reaches it (up to twelve echoes, one ink band, one hue), so a chord shape reads across the neck; the bend axis runs along the string. Touching any of a note’s sites plays it.

The theremin

No cells: the field is the cell. Five octaves run across the width — C2 at the left edge to C7 at the right, 61 semitone slots — and the note is the nearest semitone under the finger, its centre that slot’s x at the middle height. Sideways motion is continuous pitch: on a tablet a touch begins at the note under it and moves as a bend, up to the member range, re-anchoring on a new note past 47 semitones so a sweep across the whole width stays in tune; pushing away and pulling back are the press axis as everywhere. Under a controller the theremin places each note on its x and glides the drop along the width.

On the tablets: the rest of the surface

• Panic and Next are on the strip. Panic releases every voice and silences every pipe — the visualizer’s voices too, since the mapper honours CC 120 and CC 123 — and resets the strip’s wheels and the fingering. Next steps through the quick-switch subset of layouts you tick in the settings, for a change of instrument mid-piece without opening the sheet.
• Left-handed mirroring flips the lattice, the panel and the strip; the mirror is handed to every probe, so the water agrees with the hand.
• The per-device offer. The first time the app runs on a new device it offers a profile fitted to its size — the strip’s and the panel’s places, the horizontal fingering on a phone — in an alert you accept or dismiss; it is never applied on its own.
• The S Pen’s limit (Galaxy Tab). Android’s stylus palm rejection cancels every finger gesture the moment the S Pen comes within hover range of the glass, and drops the fingers until it leaves. The panel’s valves latch across that cancel and release on the next touch of the panel, but a fingering change needs the pen away from the glass; the pen plays the partials alone, and a controller’s fingering CCs play the valves beside it. The iPad has no such limit.

Not in 2.0

Microtonal and Scala tunings — cheap on the theremin and the strings, and asked about — are not built; every layout is twelve-tone equal temperament. Woodwind key systems (the Boehm charts, a much larger state space) and two-handed split layouts stay deferred with them.

For a controller

Any controller plays the thirteen layouts through MIDI alone; the fingering CCs 110–113 are the only new messages, listed in the implementation chart. The desktop and the web draw the brass with a HUD of the fingering the engine holds, the web as an overlay over the water (the web canvas).