The stylus

Fingers already bend continuously and semitone-exactly, so the pencil’s job is different: real note changes. The pen abandons the joystick — precision earns absolute-position play. Pen-as-lead, fingers-as-chords is the expressive story; palm rejection is the platform’s, so the two never collide.

Legato, per cell

Touch a key and it sounds. Slide the tip into the next cell and midi-sink emits, on the same channel, bend (to the cell offset) → Note On (new) → Note Off (old) — the classic legato overlap. Mono and MPE synths glide, DAWs record real terminated notes, the attack is in tune because the bend precedes it. A crossing commits only once the tip is 0.65 semitones past the current note, so a vibrato wiggle at a cell edge bends and never machine-guns retriggers.

• On the chromatic grid and Jankó the sounding pitch is continuous across a crossing — the offset flips sign as the reference cell changes, within cents.
• On the piano grid the in-cell bend spans half a semitone while a natural-to-natural step is a whole tone, so part of every crossing arrives as a step: a quantized glissando, the way a piano glissando is. The white-key run lives on the natural band; the black-key run runs through the corridor above it, which sustains the last pitch instead of playing.
• A stroke must start on a key. Dead zones make no call.

Velocity from force

• Apple Pencil: real tip force. A baseline tap (force 1.0, an average finger) plays at the finger default 96; a hard stab reaches 127. Force builds after contact, so sub-baseline touch-down readings clamp up, never to a whisper.
• S-Pen: normalized digitizer pressure, the same curve shape, hand-calibrated.

Continuous tip force then drives channel pressure (the ink feed, or the swirl with the pressure routing set to Swirl), change-only.

Vibrato, and the booster

Wiggle inside a cell and it bends — vibrato without retriggering, live at ×1. The bend routes like any per-note bend: glide drags the drop, or with the Ripple routing shimmers the water instead.

Roll the Pencil Pro’s barrel and the vibrato deepens, ×1 up to ×3 while rolling, decaying back to ×1 over 0.4 s once you stop. It is a gesture, not a knob: a still hand is a still value, a regrip never jumps it. Only the emitted bend is multiplied; note tracking and the crossing hysteresis stay on the raw geometry. On a pen without a roll axis (S-Pen, older Pencils) the same booster is fed by a small azimuth stir of the planted tip — lean the pen back and forth while the tip stays put. Both feeds ignore tilt changes (a tilt is posture, not a gesture) and no orientation value ever drives a knob or a vortex.

Known and accepted: with the booster engaged, a cell crossing is no longer pitch-continuous — the boosted offset can carry the pitch past the note step. Deep vibrato plus a simultaneous slide is an extreme gesture.

Up and down: CC 74

Move the tip toward the top of the screen and CC 74 rises (centre 64 at pen-down, up = brighter), shaped by the same soft knee as the joystick, change-only. With the CC 74 → Pinch routing, those slide deltas fold the water at the pen’s position along the pen’s azimuth — and the CC 74 then goes outbound only, so the loopback does not pinch twice.

The pedal

Squeeze the Pencil Pro (or hold the S-Pen’s barrel button; Pencil 2: double-tap latches) and the sustain pedal goes down — the same engine as the control strip’s Sustain pad, so the pad lights, the message rides the master channel, momentary by default and toggle behind the strip setting. Play mode only. Sustain is a musical control here: it never wipes the canvas.

The wake

Every pen stroke, in both modes, trails a dipolar wake — the water ahead of the tip bulges forward, the flanks stream back, with the tip radius following your pressure. It is physical, not musical, and is deliberately absent from the MIDI stream: a DAW recording of a pencil performance replays every note, bend, CC 74 and pressure exactly, and no wakes. A DAW has no stylus in the water. The wake operator →

Hover

Where the hardware reports hover (Pencil on M2 and later iPads, the S-Pen always), a ghost cursor shows the cell under the tip before it lands.

The S Pen and the fingers (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 — so on the brass layouts the pen cannot play the partials while a finger works the valves or the slide. The fingering panel’s valves latch across that cancel and release on the next touch of the panel, and a fingering change needs the pen away from the glass; with the pen the brass is played through a controller’s fingering CCs. The iPad has no such limit. The instruments →