Espiro vs Chladni

About: Espiro is a simple and practical drawing app for creating roulette art without the hustle of using papers and pencils. It has all you need to draw, save and share your art creation with ease in most enjoyable way possible. Features: - Draw with your finger tip on an unbounded canvas with a background color of your choice. - Enjoy the satisfaction of smooth wheel animation that draws coordinated eye catchy curves. - Combine multiple wheel types and sizes to create harmonic patterns. - Get creative with over 150+ wheel variations. - Control lines color, width and opacity. - Save your drawings on your mobile device local storage. - Show your friends your art creations on your favourite social media platform. - Get inspired by browsing in-app users gallery.

In the 18th century the physicist Ernst Chladni drew a bow across a metal plate scattered with sand, and the sand arranged itself into a pattern. When a plate vibrates, certain lines stay perfectly still. The sand settles along those quiet lines, and the pattern appears. These are Chladni figures. This app recreates that phenomenon in the palm of your hand. Three thousand grains tremble on the screen and slowly gather along the nodal lines. It is made for watching that settling happen. What you can do - Four plates, twenty patterns: switch between square, circle, triangle and ring plates. Each has five patterns, twenty in all. Every plate has its own sand colours and its own range of tones. - Turn the dial: rotating the dial changes the pattern. The sand is not reset. It slowly rearranges itself from the shape it is in into the new one, and that rearrangement is the part worth watching. - Hear the tone: each pattern has its own pitch, and the range of tones moves with the plate you choose. Turn the sound off whenever you want to watch in silence. - Sing to the sand: turn on the microphone and hum a clear, steady note. The pitch of your voice selects a pattern within the current plate, and the volume sets how wildly the sand dances. Your voice is analysed on the device as it happens. Nothing is recorded and nothing is sent anywhere. - Fill the collection: save the patterns you like with a name of your own. The collection has twenty slots, and each saved pattern is given one to three stars according to how intricate it is. Mark favourites and filter to show only those. Tap a saved pattern to bring it back to the screen. - Export a wallpaper: save the current pattern as a 1179 x 2556 PNG in your Photos. It is not a snapshot of the screen. Grains of sand are redrawn along the nodal lines computed from the equations, so the sandy texture holds up at full resolution. The mathematics is computed, not drawn The circular plate uses Bessel functions and the triangle uses the exact Lame solution, and so on for each shape. Nothing is a prepared picture being played back. Every pattern comes from an equation solved on the spot. Free, and what the one-time purchase adds Watching, switching plates, sound, microphone mode, the collection and favourites are all free. Exporting a wallpaper is free too, but while the app is free the exported image carries a faint watermark of the app name, and a small banner ad sits at the bottom of the screen (it is hidden while the collection is open and while the opening screen is showing). A single one-time purchase removes that watermark and removes the ads as well. It is the only thing for sale and it is not a subscription. Without it you can still watch every pattern, fill the whole collection, and save wallpapers. Good to know - Ads: to keep the app free, a small banner ad supplied by Google is shown at the bottom of the screen. The one-time purchase removes it. - To show those ads, information about your device and about the ads you see may be collected by Google. If you decline the tracking request shown at launch, the advertising identifier is not used. Every feature of the app works either way. - No account required - The app connects only to load ads and to buy or restore the one-time purchase - Your collection is stored only on this device - Your voice is analysed on your device, never recorded and never transmitted - Available in 33 languages Take a moment and watch the pattern rise quietly out of the sand.