Air Harp

Playing with the camera

• Sit about an arm's length back so both hands fit the frame, with light in front of you, not behind.
• Move freely — it's silent. With no pinch held, each hand's index fingertip selects on its own: it pre-lights the string nearest it, but crossing strings makes no sound. Both hands' selections show at once, marked L and R so you can see which hand is aiming where. Your other fingers never trigger anything, so either hand can travel across the whole harp to get into position without playing a note.
• Pinch to play — with either hand, or both. Hold a thumb-to-index pinch on a hand and that hand's pinch point becomes its own pick (an amber puck marked L or R). While you pinch, sweeping that pick across a string plucks it — faster crossing = louder pluck. Each hand has its own pick, so both hands can pluck at the same time: two notes — or, in Chord mode, two chords — can sound in the same moment. Release a hand's pinch and that hand is silent again instantly, free to reposition, while the other hand keeps playing.
• The badge at the stage's top-left always shows which state you're in: Moving — silent, one hand pinching, or Both hands pinching — playing. A string has to be re-crossed by the same pick to sound again — no machine-gun retriggering, and each pick keeps its own cooldown.
• Harmony comes from whichever hand is not pinching. On a free (non-pinching) hand, hold an open palm for major or make a fist for minor; the strings retune once the shape settles. A pinching hand is busy plucking, so its pose is not read for harmony — the last major/minor holds while it plays. If both hands are pinching, the key simply holds until a hand frees up. Raising or lowering a free hand brightens or darkens the tone; if both hands pinch, the brightness holds too.
• Sustain is a latch now — pinch no longer sustains. Hold an open palm still for about 1.2 seconds on a free hand to switch sustain on; hold a still open palm again to switch it off. The Sustain indicator on the stage shows the state, and counts the hold while you keep the palm still. Making a fist (minor) does not clear the latch.
• Chord mode (Play toggle below): crossing a string with a pinch held plays the whole chord built on that string's degree instead of one note — and each hand's pick triggers its own chord.
• Mouse / touch: moving without pressing is silent selection, exactly like an un-pinched hand; press and drag is a pinch — crossings fire while pressed. Two touch points pressed at once act as two picks.
• Strings look (toggle in the controls): Particles — the original dotted particle strings, the default. Glowing Columns — each string becomes a soft beam of light with a glowing core and feathered edges that flares where you pluck it. Sparks — strings shrink to faint guide lines and each pluck bursts a spray of sparks from the pluck point. Ribbons — each string flows like a ribbon of light, and a pluck sends a bright pulse travelling along it. Switch any time, even mid-play: only the rendering changes — the strings, selection, pinch clutch, chords and sound stay exactly the same, and switching fires no notes.

Why it stays in key

Every string is a scale degree, never a chromatic note, so a wild strum is an arpeggio in key instead of a mess. Pentatonic is the default — five safe notes per octave, the layout projects like AetherPlay use so any combination still sounds good.

Switch to Full scale for all seven degrees, and flip Major/Minor to hear the same strings retune — in minor, the third, sixth and seventh degrees drop, exactly as diatonic harmony says they should.

How the pluck is detected

Adapted from Gesture Synth's engineering write-up: a hit is a plucking point's path segment crossing the string — not just pointing at it — with velocity taken from crossing speed, an 80 ms cooldown per string, and a ~100 ms pose-stability rule before a hand shape commits, so chords and modes don't flicker.

Each hand's plucking point is gated by its own pinch clutch: un-pinched, that hand's index fingertip only selects and nothing it crosses can sound; pinched, its thumb–index midpoint becomes that hand's pick. The two picks are fully independent — separate crossing state, cooldowns, and re-arm — so both can fire in the same frame. While a hand pinches, its pose is ignored for harmony: major/minor and filter brightness are read from the non-pinching hand only, and hold their last values when both hands pinch. Sustain is separate from the pinch entirely: a still open palm held for ~1.2 s toggles the sustain latch. The strings themselves are fixed in place — a pluck only sets a string vibrating around its home position, capped well inside the gap to its neighbours, so strings never drag, wander, or overlap.

The string sound is a Karplus-Strong plucked-string model (the family behind Tone.js's PluckSynth), generated note by note in your browser.