neo-processing

A native desktop editor and live runtime for p5.js sketches — a modern, JavaScript-based alternative to the Java Processing IDE.

neo-processing ships as a single self-contained executable. It embeds a code editor and a live preview into a native desktop window, so you can write a p5.js sketch on the left and watch it run on the right, with the goal of real-world, full-screen deployment.

Status: v0.1.0 — active development. Interfaces and features may change.

Features

• Native desktop app — one executable, no browser or Node.js runtime required. Uses the OS webview (WebView2 on Windows, WebKitGTK on Linux).
• Embedded editor — syntax-highlighting code editor (Ace) with a resizable split between source and preview.
• Live sketch preview — run your sketch instantly in an isolated, sandboxed preview pane.
• Record & capture — record the running canvas to WebM video or capture a PNG frame, both rendered at the sketch's declared size and saved to outputs/.
• Fullscreen preview — present the sketch centred at its exact size on a white backdrop; press Esc to exit.
• Local-first & offline — the frontend and p5.js are embedded into the binary and served from a loopback HTTP server; nothing is fetched at runtime.
• Save to disk — export the current sketch to a timestamped .js file under outputs/.

Roadmap

• Full-screen rendering for deployed installations.
• Exporting standalone, editor-free applications per sketch.
• Loading arbitrary additional JavaScript libraries.

Architecture

neo-processing is a single C++ process:

1. A local HTTP server (cpp-httplib) binds to 127.0.0.1 on an OS-assigned port.
2. The web frontend (public/) is embedded into the binary at build time and served from that server.
3. A native webview window displays the frontend.

User sketches run in a sandbox="allow-scripts" iframe (opaque origin), so sketch code cannot reach the local HTTP API, cookies, or storage. The server listens on loopback only and caps request sizes.

For a deeper description of the codebase, see AGENTS.md.

Getting started

Prerequisites

Requirement	Notes
CMake ≥ 3.20	Build system.
C++20 compiler	Windows: Visual Studio 2022 Build Tools (MSVC). Linux: GCC or Clang.
Git	Required — CMake FetchContent downloads dependencies from Git.
Internet access	Needed on the first configure to download dependencies.

Windows runtime: Microsoft Edge WebView2 Runtime.

Linux build/runtime libraries: GTK 3 and WebKit2GTK development files, e.g.

# Debian/Ubuntu
sudo apt install build-essential cmake git libgtk-3-dev libwebkit2gtk-4.1-dev

Build and run

# Configure (downloads dependencies on first run)
cmake -B build

# Build
cmake --build build --target neo-processing -j --config Release

# Run
#   Windows: .\build\Release\neo-processing.exe
#   Linux:   ./build/neo-processing

Use --config Debug (and the Debug output folder) for a debug build.

Helper scripts

# Windows — initialises the MSVC environment, configures, builds Debug, and runs.
.\build_and_run.bat

# Linux — configures, builds Debug, and runs.
./build_and_run.sh

build_and_distribute.bat is a placeholder for the future Release packaging pipeline and is not yet implemented.

Dependencies

Downloaded automatically into the build tree (build/_deps/) at configure time; not committed to the repository:

Dependency	Purpose
cpp-httplib	Local HTTP server.
webview	Native desktop window + system webview.
cpp-embedlib	Embeds public/ into the executable.
Boost (asio, system)	Async infrastructure thread.

The frontend libraries in public/libs/ (Ace, p5.js) are vendored and committed.

Project layout

src/main.cpp        C++ application: HTTP routes, window, shutdown
public/             Frontend, embedded into the binary at build time
  index.html        Layout
  script.js         Editor, menus, file I/O, sketch runner
  style.css         Styling
  libs/             Vendored Ace + p5.js
outputs/            Saved sketches (runtime output)
icons/              Application icons
assets/             README images
CMakeLists.txt      Build configuration
AGENTS.md           Detailed guide for contributors and AI agents

Troubleshooting

• Windows: MinGW/MSYS2 header conflicts (corecrt.h / winnt.h errors). MSVC is picking up MinGW headers. Build from a clean Developer Command Prompt for VS, or use build_and_run.bat, which sanitises the environment.
• Windows: "Windows SDK version … was not found". A stale build/CMakeCache.txt references an SDK that is no longer installed. Delete the cache and reconfigure (or run build_and_run.bat, which clears it automatically).

Security

The app runs user-provided JavaScript inside a sandboxed WebView and a loopback-only HTTP server. See SECURITY.md for the security model and how to report a vulnerability.

License

Released under the MIT License. See LICENSE.