libprocessing

libprocessing is an experimental native library with the goal of supporting the implementation of the core Processing API in a variety of languages. The library is written in the Rust programming language and built on top of the Bevy game engine. libprocessing uses WebGPU as its rendering backend and is designed to (eventually) support desktop, mobile, and web targets.

You can learn more about this project from this talk at LibreGraphicsMeeting 2026

There is two different things at work here :

• libprocessing (this repo) is the low-level cross-platform library for the core Processing API. It's written in Rust, and thus lets write Processing sketches in Rust.
• mewnala is a Python package built directly from libprocessing, providing Python bindings for the library. It's available as any other Python package out there and lets you write Processing sketches in a Python environment, regardless of you having libprocessing or Rust installed.

Inside of our processing_pyo3 crate we have created a python package that you can easily install with pip. Again, we are still very nascent, but let us know what kinds of snags you may run into while getting this set up. Try running the examples in the processing_pyo3 examples directory.

We are big fans of uv and this is the easiest way to get started using mewnala

curl -LsSf https://astral.sh/uv/install.sh | sh

powershell -ExecutionPolicy ByPass -c "irm https://astral.sh/uv/install.ps1 | iex"

We're going to create a folder named mewnala-sketchbook and install the mewnala package inside:

# Initialize a project with uv
uv init mewnala-sketchbook && cd mewnala-sketchbook

# add the package
uv add mewnala

Now create a file named sketch.py at the root of mewnala-sketchbook.

You can use this code to test

from mewnala import *

def setup():
    size(400, 400)
    background(255)

def draw():
    push_matrix()
    translate(mouse_x, mouse_y)
    fill(255, 100, 200)
    circle(0, 0, 50)
    pop_matrix()

run()

Now run your sketch using:

# run a sketch
uv run sketch.py

Note: you can use any file name you want for your sketch

You'll need to install the Rust toolchain to work on this project. Most users will want to install Rust via rustup, which helps manage Rust toolchain versions.

When cloning this repo (or your fork), don't forget to install its submodules (eg. Lygia)

git clone --recurse-submodules git@github.com:processing/libprocessing.git

if you already cloned the repo without --recurse-submodules, you can run

git submodule update --init

This project uses just as a command runner:

cargo install just

Run just to see available commands.

The processing_wasm crate provides WebAssembly bindings that expose a JavaScript API mirroring the C FFI.

Install wasm-pack:

cargo install wasm-pack

On Windows, you'll need to manually install wasm-opt

cargo install wasm-opt

You'll also need the wasm32 target:

rustup target add wasm32-unknown-unknown

just wasm-build

This outputs the package to target/wasm/.

just wasm-serve

Note: you'll need python installed on your machine to run this command

We want your help building this library!

One place we could really use some help is with porting Processing examples to using mewnala, and then reporting where you get stuck or where things could be easier. Check out the effort here: https://github.com/processing/processing-examples-mewnala.

You can see a list of outstanding tasks in our issues. However, while we're still in the early phases, consider checking in with us first in the #devs-chat channel on Discord to coordinate our efforts.

You can read our project design principles here.