> ## Documentation Index
> Fetch the complete documentation index at: https://docs.facebetter.net/llms.txt
> Use this file to discover all available pages before exploring further.

# API Reference

> Facebetter SDK C++ API reference for Linux

The Linux C++ SDK API is **identical** to the Windows API. Please refer to:

👉 [Windows C++ API Reference](/windows/api-reference)

The sections below cover Linux-specific notes only.

***

## Linux-Specific Notes

### Shared Library Loading

The SDK ships as a shared library `libfacebetter.so`. At runtime the OS must be able to locate it:

```bash theme={null}
# Option 1: LD_LIBRARY_PATH (recommended during development)
export LD_LIBRARY_PATH=/path/to/facebetter-sdk/lib:$LD_LIBRARY_PATH
./your_app

# Option 2: Add to ldconfig (system-wide installation)
echo "/path/to/facebetter-sdk/lib" | sudo tee /etc/ld.so.conf.d/facebetter.conf
sudo ldconfig

# Option 3: Copy to a system library directory
sudo cp libfacebetter.so /usr/local/lib/
sudo ldconfig
```

### CMake Linkage

```cmake theme={null}
target_include_directories(your_target PRIVATE
    /path/to/facebetter-sdk/include
)

target_link_libraries(your_target PRIVATE
    ${CMAKE_CURRENT_SOURCE_DIR}/lib/libfacebetter.so
    # OpenGL dependencies
    GL
    glfw
)
```

### OpenGL Environment

A valid OpenGL context is required. Install the necessary graphics libraries first:

```bash theme={null}
# Ubuntu / Debian
sudo apt install libgl1-mesa-dev libglu1-mesa-dev libglfw3-dev

# Fedora / RHEL
sudo dnf install mesa-libGL-devel mesa-libGLU-devel glfw-devel
```

For headless servers (no display), use Mesa's off-screen rendering:

```bash theme={null}
# Ubuntu / Debian
sudo apt install libosmesa6-dev
```

### `external_context` Field

If your application already manages an OpenGL context (e.g. via GLFW), set:

```cpp theme={null}
EngineConfig cfg;
cfg.external_context = true;  // Use the caller's current GL context
```

When `true`, the SDK does not create an internal GL context; all GPU calls run on the calling thread's active context.

### `SetRenderView` Not Available

This method exists only on iOS and macOS. Do not call it on Linux.

### DISPLAY Environment Variable

When using a windowed GLFW display, an X11 or Wayland server must be present:

```bash theme={null}
echo $DISPLAY   # should print something like :0 or :1
```

For remote SSH sessions, enable X11 forwarding:

```bash theme={null}
ssh -X user@host
```

***

## Full API Documentation

For the complete reference covering all methods, enumerations, and data structures, see the [Windows C++ API Reference](/windows/api-reference) — it applies equally to Linux.