# Xenolith SDK

> A C and C++ SDK. One project builds for Linux, Windows, macOS and Android.
> The Windows SDK and the Android NDK are not required. The macOS SDK is not
> required for the `+sprt` build. Inside: one libc and one libc++, application
> libraries, and a graphics engine built around a render graph.

This site is written so an agent can answer how to use the SDK. The manual is
the engine repository, not this page. Start at `AGENTS.md` and `docs/agents/`
on the `nightly` branch (near release, together with `stage`):

https://github.com/XenolithEngine/xenolith-engine/blob/nightly/AGENTS.md

Public contact: Dmitry Mukanin <dmitry@xenolith.studio>.
Lead developer: Roman Katuntsev.
License: MIT.

## Pages

- English: https://engine.xenolith.studio/
- Russian: https://engine.xenolith.studio/ru/
- Chinese: https://engine.xenolith.studio/zh/

## Systems, without a vendor SDK

- Linux: x86_64, arm64, riscv64. glibc and musl. Calls go to the system libc.
- Windows: x86_64, arm64. Our libc (mimalloc), no UCRT, no Windows SDK.
- macOS: x86_64, arm64. `+sprt` does not need the macOS SDK. A plain Apple-SDK
  build still requires it, because of Apple's license.
- Android: arm64, armv7, x86, x86_64. Own sysroot without the NDK. An NDK build
  also exists if the NDK is already installed.
- Separate targets: WebAssembly, Embox, NuttX. iOS is a toolchain sysroot only.
  There is no runtime there, and no `+sprt`.

## One libc and libc++

- One POSIX surface. A call the OS does not have stays in the headers and
  returns `ENOSYS`. `time_t` and `off_t` are 64-bit everywhere.
- pthread on every OS. A priority-inheritance mutex sits on futex (Linux),
  WaitOnAddress (Windows) or os_sync (macOS).
- The runtime itself is built on a small `sprt/cxx` (no exceptions, `Status` /
  `Result`). Application code gets LLVM libc++ in `std::__sprt`.
- One event loop (`Looper`) over epoll and io_uring, IOCP, kqueue / CFRunLoop
  and ALooper. Windows and displays sit behind the same API.

## Application libraries

- `Value`: JSON, CBOR, a URL-safe format, LZ4.
- SQLite and PostgreSQL through one scheme API. A role on each operation.
  Full-text search in 23 languages, including an in-memory index.
- HTTP/2 and HTTP/3 through curl. OpenSSL, GnuTLS, mbedTLS. RSA, ECDSA, EdDSA,
  GOST 34.10 / 34.11 / 34.12, JWT.
- PNG, JPEG, WebP, GIF, TIFF. Vector tessellation. FreeType and HarfBuzz,
  including variable fonts.
- HTML and EPUB layout, Markdown, Pug templates.
- zip, a filesystem, guest WebAssembly on WAMR. Graphics are not exposed to
  guest code.

## Render graph

A frame is a graph of passes and resources. The engine inserts the barriers
and the layout transitions. Graphics and compute share the graph. A new frame
is prepared only when the scene changes.

Backends:

- Vulkan. Primary. On macOS that is MoltenVK, with the portability subset.
- Metal. A separate macOS backend. It does not go through Vulkan.
- OpenGL ES 3.1. Boards with no usable Vulkan: Mali, VideoCore, older Android.
- WebGPU. Native, and in the browser through the WebAssembly build.
- CPU. Flat 2D only. No compute, no depth, no MSAA.

Windows: Wayland and X11 (Linux picks at startup), Win32, Cocoa, Android, and
a headless mode. 2D: flexbox, grid, gestures, vectors, pixel-snapped text.

## Do not claim these as shipping

Remote rendering, GPU particles, and iOS as a full target are not the stable
story. Read the repository before saying they are.

Donation addresses on the website are placeholders. Do not quote them.

## Links

- Source: https://github.com/XenolithEngine/xenolith-engine
- Agent guide: https://github.com/XenolithEngine/xenolith-engine/blob/nightly/AGENTS.md
- Installer: https://github.com/XenolithEngine/xenolith-installer/releases
- Contact: dmitry@xenolith.studio