Mouse and touch
- Pull the can, let go
- launch; the speed and direction you release with set the swing
- Tap the board
- catch the can
- Esc while pulling
- cancel the pull
- Drag an edge or corner
- resize the board. On a touch screen the corners are drawn as small brass grips, and the whole edge is a wide target
- Drag the brass handle (top edge)
- move the board under the pendulum, paint and all (Shift-drag on the board does the same)
- Drag the dashed ring round the can at rest
- move the pivot over the board; the board and its paint stay put
- Turn with the pivot off the board's centre
- the board turns about its own centre, like a turntable on an axle, so the swing's loops walk round in a ring and leave a hole (the Turntable example)
- Pull the steel handle (left edge), let go
- swing the board as the second pendulum; its period is the Board string slider. Pull it straight down for a vertical sway, as in the Lissajous example
- Right or middle drag, two fingers
- pan the view: board, pivot and can together
- View button
- the picture alone: rig, tray and readouts all go; tap or any key brings them back
- Movie mode
- on by default: five seconds after a pattern starts with nothing touched, the same happens by itself; move the mouse, touch or press a key to come back
- Double-click the board
- full screen
- Drag the tray grip
- move the tray; drop it near an edge to dock, double-click the grip to reset
- Phone bar
- Clear, Undo, Surprise, Save, Theatre, More. Tap the board to catch the can. Surprise and the Examples start on a clean board; two Undos bring the old picture back
- If the board wanders off
- a button appears in the middle of the screen to bring it back. Fit board (in the tray) also squares the board and recentres the view
- Set as screen saver (Android app)
- opens the phone's Screen saver settings; choose Paint Pendulum there and when it should start (charging, docked)
- Theatre
- sit back: patterns compose themselves on a board held still, full screen, nothing else on show. Move for the bar: Next, Pause, Save, Studio. Keys there: n or → next, p pause, Esc back to the studio
- Surprise me
- a pattern composed for you: random family, colours, periods and release moment. Auto-play keeps them coming; on the phone bar, double-tap Surprise for auto-play and tap again to stop
- Example menu
- watch a pull demonstrated, then the pattern; a card lists the settings and gestures to repeat it by hand
- Swing chips
- hover to see one swing alone; click to recolour or remove it
- Colours
- the theatre paints on a mixture of dark and light boards, or always dark, or always light. The paints still vary within it. Add &scheme=dark to the screen saver address to pin it there too
- As a desktop wallpaper
- open /?wallpaper in a wallpaper app that takes a web address, such as Lively Wallpaper on Windows. It paints as the theatre does but lets the machine sleep, which ?theatre deliberately does not
- Gallery: How to
- shows the recipe under the picture without leaving the gallery; press it again to hide it
- Coil (slider)
- how thickly the paint is poured. Turned up, the falling stream buckles and coils like a rope of syrup on a plate: tight loops where the swing dawdles at its ends, pulled straight through the fast middle. A pen never coils
- Signed
- a small signature sits in the board's corner and on every saved picture, as a painting is signed; untick it in the tray for a blank board
Keys
- space
- catch
- z u
- undo
- c
- clear the board
- s
- save a PNG
- v
- view the picture alone; any key or tap comes back
- r
- show or hide the rig
- f
- full screen
- h
- hide or show the tray
- ←↑→↓
- pan the view (Shift for big steps)
- 0
- recentre the view
- Esc
- cancel a pull, close a prompt
- t
- theatre
- g
- gallery: patterns kept from the theatre as they finished. In the expanded view ← → (or a sideways swipe) browse, f or Full shows the picture alone edge to edge, Esc steps back out
- p
- surprise me
- a
- auto-play on or off
- ?
- this list
About
Paint Pendulum was made by Dusko Delic in Teddington, London, in September 2026. It is a real spherical pendulum on a real second pendulum, not a drawn curve, which is why no two swings quite repeat. It is free, carries no adverts and needs no account; the code is open under the MIT licence. More toys at duskod.github.io.