rmatrix

rmatrix is an implementation of the cmatrix project, but in Rust using the ratatui crate.

Installation

The crate name on crates.io is rjmatrix (someone took rmatrix).

cargo install rjmatrix

Usage

Usage: rjmatrix [OPTIONS]

Options:
  -c, --color <COLOR>          blue, cyan, red, purple, yellow, green, rainbow
  -s, --speed <SPEED>          1 (slowest) - 10 (fastest)
  -d, --direction <DIRECTION>  up, down, left, right
  -b, --bold                   Bold text
  -h, --help                   Print help

Runtime keys

Key	Action
c	Cycle to a random color
0 – 9	Change speed (0 = fastest)
↑↓←→	Change direction
b	Toggle bold
q	Quit

Features

• Resize-aware (vertical and horizontal)
• Depth effect: streams fade from white head to dim tail using a sqrt curve over line length
• Per-stream brightness variation for layered/3D feel
• Rainbow mode picks a locked color per stream
• Bold only highlights the head

Development

With devenv (recommended)

This repo uses devenv + direnv to provide a reproducible Rust toolchain.

cd rmatrix
direnv allow    # one-time, after install

devenv will provide rustc, cargo, etc. The toolchain is pinned in devenv.nix.

Without devenv

Any Rust stable toolchain >= 1.85 (required for edition = "2024").

Build & run

cargo run --release    # release mode is meaningfully smoother
cargo check            # fast type-check loop while editing
cargo build --release  # produces target/release/rjmatrix

Install locally from source

cargo install --path .

Drops the binary in ~/.cargo/bin/rjmatrix.

Nix build

The repo ships a flake using rustPlatform.buildRustPackage. Cargo.lock is the only source of truth — no extra generated files.

nix build
./result/bin/rjmatrix

Consuming from another flake

{
  inputs.rmatrix.url = "github:RoastBeefer00/rmatrix";
  # ...
  environment.systemPackages = [ inputs.rmatrix.packages.${system}.default ];
}

Updating flake inputs

nix flake update    # bumps nixpkgs / flake-utils pins

Release flow

1. Bump version in Cargo.toml and flake.nix
2. cargo build --release (sanity check)
3. nix build (confirm reproducible build still works)
4. Tag + push: git tag v1.x.y && git push --tags
5. cargo publish