👐 Theremotion is a virtual instrument inspired by the Theremin.

Just like a Theremin, the position of your hand in the air controls the pitch and volume of the sound. However, you can also control much more dimensions of the sound with specific motions.

With specific hand positions, you can control a low pass filter, a supersaw sound, a guitar sound and more. You can even make the instrument "stick" to a scale, making it much easier to control than a Theremin.

Head over to the Theremotion website for instructions on usage and installation.

The hand tracking is provided by Ultraleap's Leap Motion Controller.

The sound generation is created with Grame's Faust.

The UI is built with Slint.

The program is built with Rust.

In order to build Theremotion, you need to install Rust and Ultraleap's tracking software. If you wish to modify the sound generation, you also need to install Faust.

Build with cargo build. When modifying the DSP, set the environment variable THEREMOTION_REGEN_DSP to any value in order to regenerate the DSP code when running cargo build.

If using the Orion version of Ultraleap, build with cargo build --no-default-features.

If the tracking software is installed at a custom path, set the environment variable LEAPSDK_LIB_PATH to the absolute path of the Ultraleap/LeapSDK/lib/x64 before running the build.

Building on Linux requires to install some development libraries including:

• libasound2-dev

The source code is divided into 3 crates:

• theremotion is the main crate
• theremotion-dsp contains the DSP producing the audio, generated with Faust
• theremotion-ui contains the user interface, generated with Slint

Theremotion is run by 4 main threads:

• conductor receives the updates from all the other threads and transmits them. It contains all the movement definitions and holds the settings
• leap provides the hand tracking messages
• dsp_controller manages reads the parameter messages and manages the DSP state
• dsp produces the sounds based on the DSP state
• ui is the main thread and provides the user interface

flowchart TD
leap -->|hand tracking| conductor
ui -->|user input| conductor
conductor -->|ui update| ui
conductor -->|parameter update| dsp_controller
dsp_controller --> |dsp state| dsp

With the exception of any third-parties (such as the Rust, Faust and Ultraleap logos, the Ultraleap redistributables, the Noto Emoji fonts), Theremotion is distributed under the GPLv3 license. Its DSP ("theremotion-dsp") is distributed under the BSD license.