Update Linux build to use Docker with Ubuntu 16.04 for better glibc compatibility

- Migrate build-linux job from ubuntu-20.04 runner to Docker container
- Use ubuntu:16.04 image for glibc 2.23 compatibility with older systems like Slackware 14.2
- Replace actions/setup-java with manual OpenJDK 8 installation in container
- Remove sudo commands since container runs as root
- Add CLAUDE.md documentation for future development

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: electronstudio

.github/workflows/build.yml

@@ -13,30 +13,38 @@ env:
 
 jobs:
   build-linux:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
+    container:
+      image: ubuntu:16.04
+      options: --user root
 
     steps:
       # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
       - uses: actions/checkout@v2
         with:
           submodules: recursive
 
-      - uses: actions/setup-java@v2
-        with:
-            distribution: 'adopt' # See 'Supported distributions' for available options
-            java-version: '8'
+      - name: Install dependencies
+        run: |
+          apt update
+          apt install -y wget curl git build-essential cmake
+          apt install -y libasound2-dev mesa-common-dev libx11-dev libxrandr-dev libxi-dev xorg-dev libgl1-mesa-dev libglu1-mesa-dev libwayland-dev libxkbcommon-dev
 
+      - name: Setup Java 8
+        run: |
+          apt install -y openjdk-8-jdk
+          export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64
+          echo "JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64" >> $GITHUB_ENV
+          echo "/usr/lib/jvm/java-8-openjdk-amd64/bin" >> $GITHUB_PATH
 
       - name: Build raylib
         run: |
-          sudo apt update
-          sudo apt install libasound2-dev mesa-common-dev libx11-dev libxrandr-dev libxi-dev xorg-dev libgl1-mesa-dev libglu1-mesa-dev libwayland-dev libxkbcommon-dev
           cd raylib
           mkdir build
           cd build
           cmake -DBUILD_EXAMPLES=OFF -DCUSTOMIZE_BUILD=ON -DSUPPORT_FILEFORMAT_JPG=ON -DSUPPORT_FILEFORMAT_FLAC=ON -DWITH_PIC=ON -DCMAKE_BUILD_TYPE=Release ..
           make -j2
-          sudo make install
+          make install
 
       - name: Build jaylib
         env:

CLAUDE.md

@@ -0,0 +1,91 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project Overview
+
+Jaylib is a Java Native Interface (JNI) binding library for Raylib 5.5, providing Java developers with access to the popular C game development library. The project uses JavaCPP to automatically generate JNI bindings from the native Raylib headers.
+
+## Build System and Commands
+
+### Primary Build Commands
+- `./build-java.sh` - Main Java compilation and JAR creation (requires `RAYLIB_VERSION` environment variable)
+- `./build-linux.sh` - Linux platform-specific build
+- `./build-windows.sh` - Windows platform build (requires Visual Studio environment)
+- `./build-native.sh` - Native library compilation
+
+### Testing
+- `./run-test.sh` - Run the basic functionality test (requires `RAYLIB_PLATFORM` environment variable)
+- `./run-test-jar.sh` - Run tests using the compiled JAR
+
+### Documentation
+- `./build-docs.sh` - Generate Javadoc documentation
+
+### Environment Variables Required
+- `RAYLIB_VERSION` - Version string for builds (e.g., "5.5.0-0")
+- `RAYLIB_PLATFORM` - Platform identifier (e.g., "linux-x86_64", "windows-x86_64", "macosx-x86_64")
+
+## Architecture and Key Components
+
+### Core Structure
+- **JavaCPP Integration**: Uses `javacpp.jar` and JavaCPP annotations in `RaylibConfig.java` to automatically generate JNI bindings
+- **Multi-stage Build Process**: 
+  1. Generate Java bindings from C headers using JavaCPP
+  2. Compile native code with platform-specific linkers
+  3. Package everything into distributable JARs
+
+### Key Source Files
+- `src/com/raylib/RaylibConfig.java` - JavaCPP configuration defining platform-specific linking and header includes
+- `src/com/raylib/Raylib.java` - Auto-generated main binding class (created during build)
+- `src/com/raylib/Colors.java` - Predefined color constants (RAYWHITE, BLACK, etc.)
+- `src/com/raylib/Helpers.java` - Alternative constructor methods for structs
+- `src/com/raylib/Test.java` - Basic functionality test and demo
+
+### Native Headers
+The project includes Raylib C header files:
+- `raylib.h` - Core Raylib API
+- `rlgl.h` - OpenGL abstraction layer
+- `raymath.h` - Math utility functions
+- `physac.h` - Physics simulation
+- `raygui.h` - Immediate mode GUI
+
+### Platform Support
+Configured for cross-platform builds supporting:
+- Windows x86_64
+- macOS x86_64 and ARM64
+- Linux x86_64 and ARM64
+
+## JavaCPP Binding Specifics
+
+### Field Access Pattern
+- Getters: `vector.x()` returns the x field value
+- Setters: `vector.x(3)` sets the x field to 3
+- Position field renamed to `_position` due to JavaCPP's internal position field
+
+### Struct Initialization
+JavaCPP uses fluent constructor syntax:
+```java
+var vec = new Vector3().x(1).y(2).z(3);
+```
+Alternative constructors available in `Helpers.java`:
+```java
+var vec = Helpers.createVector3(1, 2, 3);
+```
+
+### Array Access
+C arrays are not Java arrays - use position() method:
+```java
+model.materials().position(1).maps().position(2)  // Second map of first material
+```
+
+## Build Dependencies
+- Java 8+ (JDK required for compilation)
+- Platform-specific C++ compiler (GCC on Linux, Visual Studio on Windows, Xcode on macOS)
+- JavaCPP tool (included as `javacpp.jar`)
+- Raylib native library (included as git submodule)
+
+## macOS Specific Requirements
+When running Java applications on macOS, use the `-XstartOnFirstThread` JVM option:
+```bash
+java -XstartOnFirstThread -cp jaylib.jar:. MyGame
+```