A live camera feed, rendered as edge-detected braille art, straight in your terminal. mirror-bash grabs frames from your webcam, runs Sobel edge detection on each one with OpenCV, and maps the result onto a brightness-sorted Braille Unicode ramp turning your terminal into an

Requirements

• CMake 3.16+
• A C++20 compiler (tested with AppleClang/Clang on macOS)
• OpenCV (4.x recommended), discoverable via find_package(OpenCV)
• A webcam
• A real terminal emulator (not a piped/non-interactive shell) — the live view uses raw terminal input and the alternate screen buffer

macOS install of OpenCV via Homebrew:

brew install opencv

Building

git clone <this-repo-url>
cd mirror-bash
cmake -B build
cmake --build build

This produces the mirror-bash executable inside build/.

Usage

Run it from an interactive terminal:

./build/mirror-bash

• On first run, macOS will prompt for camera access for your terminal app — allow it, or mirror-bash won't be able to open the camera.
• A banner is shown while the camera warms up, then live frames take over.
• Press q or Esc to quit at any time.
• The app also auto-exits after 5 seconds as a hard runtime cap.
• On exit, the camera and capture thread are shut down and your terminal is restored to its normal state (cursor and scrollback included).

How it works

• CameraCapture opens the webcam and runs a background thread that continuously grabs and resizes frames.
• FrameBuffer is a thread-safe single-slot hand-off between the capture thread and the render loop, so the main thread always renders the latest available frame.
• FrameRenderer runs Sobel edge detection on each frame, then maps the gradient magnitude onto a ramp of Braille Unicode glyphs sorted by dot count (sparse dots = dark/flat areas, dense dots = strong edges).
• TerminalGuard puts the terminal into raw input mode and the alternate screen buffer for the duration of the run, restoring everything on exit.

Troubleshooting

• "ERROR! Unable to open camera" — another app may be holding the camera, or camera permission wasn't granted to your terminal. Check System Settings → Privacy & Security → Camera.
• Nothing but the banner shows — the camera is taking a while to warm up; it should switch to live frames once the first one arrives, or the app will time out after 5 seconds.
• Garbled characters instead of braille art — make sure your terminal's locale/encoding is UTF-8 (most modern terminals are by default).