Blight: Bias Lighting for Wayland

Real-time bias lighting system for Linux Wayland using ESP32 + WS2812B LEDs. Captures screen edges via PipeWire (using XDG Desktop Portal) and sends RGB data to ESP32 over WiFi.

Overview

Uses libportal and PipeWire to capture screen borders, downsamples to an LED grid, and transmits color data to an ESP32 via UDP. Optimized for minimal CPU usage and low latency by accessing native PipeWire buffers.

Workflow:

1. Request screencast via XDG Desktop Portal (libportal).
2. Capture buffers directly from PipeWire (supports DMA-BUF and MemFd).
3. Sample edges (Left, Top, Right) and average colors.
4. Transmit RGB data to ESP32 over WiFi/UDP.

Hardware

• ESP32 with WiFi
• WS2812B LED strip (connected to GPIO 14)
• USB-C power supply
• Recommended setup: ~62 LEDs for a standard monitor

Build

Prerequisites

Ensure you have the following development libraries installed:

• libportal
• glib-2.0
• libpipewire-0.3
• pkg-config
• gcc
• make

Compilation

Simply run:

make

This builds the blight binary. The default configuration uses WiFi communication.

Usage

./blight [brightness] [saturation] [smoothing]

Parameters:

• brightness: 0-255 (default: 150)
• saturation: float (default: 1.0, determines color vibrancy. Try 1.5-2.0)
• smoothing: 0.1-1.0 (default: 1.0, lower values = smoother transitions)

Example:

./blight 200 1.8 0.7

ESP32 Setup

1. Credentials: Create esp32/main/creds.h with your WiFi info:

   #define WIFI_SSID "YourSSID"
   #define WIFI_PASS "YourPassword"

2. Configuration: Adjust NUM_LEDS and DATA_PIN in esp32/main/main.ino if necessary.
3. Flash: Use Arduino IDE or arduino-cli to flash the ESP32.
4. Network: The host app expects the ESP32 at 192.168.1.100 (static IP) by default. You can change this in src/main.c.

Performance Note

CPU usage is minimal (<2%) as it avoids heavy processing pipelines. Note that any PipeWire screencast may cause minor FPS drops in some Wayland compositors (like GNOME/Mutter) due to how they handle buffer synchronization.

TODO

• Daemon + Control Tool: Implement blightd daemon with blightctl for runtime control.
• XDG Portal Token Restoration: Save authorization token to avoid permission dialogs on startup.
• Black Boundary Detection: Automatically skip black bars (letterboxing) for different aspect ratios.