rust-digital-rain

A Matrix-style digital rain animated desktop wallpaper written in Rust. A falling stream of characters renders in each column of the screen, leaving glyphs behind at fixed positions as the lead character descends. Characters near the head rotate quickly, fade gradually, and occasionally flash bright before dimming back into the trail. Runs as a non-interactive background window via xwinwrap and alacritty at 24 fps.

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Installation

1. Rust

These instructions assume Rust is already installed on your system. If not, visit rust-lang.org and follow the instructions there.

2. xwinwrap

xwinwrap hosts the terminal emulator as a desktop-level window that sits behind all other windows and ignores mouse/keyboard input. Build it from source:

sudo apt install libx11-dev libxrender-dev libxext-dev
git clone https://github.com/mmhobi7/xwinwrap
cd xwinwrap
make
sudo make install

3. Alacritty

Alacritty is the terminal emulator used to render the animation. Visit alacritty.org for full documentation.

sudo add-apt-repository ppa:aslatter/ppa
sudo apt update
sudo apt install alacritty

4. Matrix Code NFI font

The wallpaper uses the Matrix Code NFI font.

1. Download it from dafont.com/matrix-code-nfi.font
2. Extract the zip and double-click the .ttf file
3. Click Install in the font preview window that opens

5. Clone and build

git clone https://github.com/Kenneth-Posey/rust-digital-rain.git
cd rust-digital-rain
cargo build --release

Run as a background wallpaper

bash launch.sh

The script builds the binary (if not already built), then launches xwinwrap with alacritty embedded as a borderless, non-interactive desktop background window. The process will appear as digital-rain in your process explorer.

Stop the wallpaper

bash stop.sh

Tuning the animation

launch.sh passes all animation parameters as explicit CLI flags — edit the values there to adjust the defaults:

Flag	Default	Description
--speed	1.0	Column fall speed multiplier
--fps	24	Target frame rate
--trail-length	60	Maximum trail length in rows
--flash-chance	5	Chance (0–100) per tick a glyph flashes bright
--rotation-speed	1.0	Glyph rotation speed multiplier
--config	(none)	Path to a YAML config file enabling source-code rain mode
--check	—	Load config, print path diagnostics to stdout, then exit

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Source Code Rain

Instead of random glyphs, the rain can display real lines of source code read from your own projects. Each column is assigned one line from a source file; characters spin randomly as the head falls, then snap to the correct character once they settle. Keyword characters (e.g. fn, class, return) are highlighted in bright white-green — the same color as the leading glyph — when keyword highlighting is enabled. Digit characters (0–9) can be highlighted the same way with highlight_numbers: true. Documentation comment lines are filtered out and never shown.

Config file format

# Extensions to include when scanning directories (global)
extensions:
  - rs
  - py
  - ts

# One entry per directory; options are per-path
paths:
  - path: /path/to/my/project/src
    highlight_keywords: true  # brighter color for language keywords
    highlight_numbers: true   # brighter color for digit characters

  - path: /path/to/other/project
    highlight_keywords: true  
    highlight_numbers: false

# Doc-comment prefixes per language — matching lines are skipped entirely.
# Multiple prefixes are comma-separated.
doc_comments:
  rust: "///, //, //!"
  python: "\"\"\", '''"
  # … see config.yml for the full list

# Keyword lists — applied when highlight_keywords is true.
# Keys are language names (rust, python, javascript, etc.)
keywords:
  rust: "fn, pub, async" # … see config.yml for the full list

Supported languages for keyword highlighting

Java, Kotlin, C#, Rust, Python, JavaScript, TypeScript, F#, Haskell, Swift, Clojure, PHP, COBOL, Visual Basic / VB.NET, SQL, C++, C, Ruby, Dart, R, Go.

Adding private paths with config.secret.yml

To add directories from private projects without committing them, create a config.secret.yml file in the same directory as config.yml. It uses the exact same format and is automatically merged at startup. It is already listed in .gitignore.

1. Create the file next to config.yml

touch config.secret.yml

2. Add your private paths (and optionally extra extensions or keywords)

paths:
  - path: /home/you/work/my-private-repo/src
    highlight_numbers: true
    highlight_keywords: true
  - path: /home/you/personal/side-project
    highlight_numbers: true
    highlight_keywords: false

3. Run as normal — your private paths will be included in the file rotation alongside the public ones

bash launch.sh