Huorn

A Minecraft Java Edition mod that embeds a fully functional Alacritty terminal emulator as an interactive block. Place a terminal block in your world, right-click it, and get a real shell session rendered on the block face.

Features

• Real terminal emulation — powered by alacritty_terminal v0.25 (same engine as the Alacritty desktop terminal)
• Full ANSI color support — 256 colors + true color, bold, italic, underline, strikethrough
• In-world rendering — terminal content rendered as a texture on the block face using fontdue font rasterization
• Full-screen GUI overlay — press F12 for a larger view
• Focus mode — right-click to capture all keyboard input; ESC to exit
• Cross-loader — supports both Fabric and Forge via Architectury
• Local PTY — spawns a real shell process on the player’s machine

Requirements

• Minecraft Java Edition 1.20.1
• Fabric Loader 0.15+ with Fabric API, or Forge 47.2+
• Architectury API 9.2+
• macOS (aarch64) — other platforms need native library cross-compilation

Quick Start

Building

# Build the Rust native library
cd rust && cargo build --release

# Copy native to mod resources
mkdir -p common/src/main/resources/natives/macos-aarch64
cp rust/target/release/libhuorn_minecraft.dylib common/src/main/resources/natives/macos-aarch64/

# Build the mod (requires Java 21)
export JAVA_HOME=/opt/homebrew/opt/openjdk@21/libexec/openjdk.jdk/Contents/Home
./gradlew build

Running

# Launch Minecraft dev client
./gradlew :fabric:runClient

In-Game Usage

1. Open creative inventory → “Huorn” tab Or use: /give @s huorn:terminal_block
2. Place the terminal block — it faces toward you
3. Right-click the block to start the terminal and enter focus mode
4. Type commands — all keyboard input goes to the terminal
5. F12 — opens full-screen terminal overlay
6. ESC — exits focus mode (returns to normal Minecraft controls)
7. Mouse scroll — scrolls terminal history

Architecture

Shell Process (local PTY)
  ↓ raw bytes
alacritty_terminal VTE parser → grid cells (char + fg/bg + flags)
  ↓
fontdue glyph rasterizer + LRU cache (4096 glyphs)
  ↓
RGBA pixel buffer (Vec<u8> in Rust, ~1MB)
  ↓ JNI: nativeGetPixelData() → direct ByteBuffer
Java NativeImage → DynamicTexture → OpenGL texture
  ↓
BlockEntityRenderer (textured quad on block face)

Tests

# Rust tests (46 tests: glyph cache, renderer, key translation, terminal lifecycle)
cd rust && cargo test

# Java compilation verification
./gradlew build

Project Structure

rust/src/           — Native JNI library (Rust)
  lib.rs            — JNI entry points
  terminal.rs       — Terminal state, PTY, VTE parsing
  renderer.rs       — Pixel buffer renderer
  glyph_cache.rs    — fontdue font rasterization + LRU cache
common/src/         — Shared Minecraft mod code (Architectury)
  block/            — TerminalBlock, TerminalBlockEntity, ScreenGroup
  nativelib/        — NativeTerminal (JNI), NativeLoader (platform detection)
  client/           — Renderer, screen, input handling
  mixin/            — KeyboardHandler char input interception
fabric/             — Fabric-specific entrypoint
forge/              — Forge-specific entrypoint