Build dependencies

This guide describes configuration from the SDK repository root. The examples target BasicApp and keep tests and Ceto disabled. Package-manager builds still need clean-build and runtime validation before the release.

Tools you install yourself

A C++17 compiler and platform SDK. On Windows, select Visual Studio's Desktop development with C++ workload, including MSVC, a Windows SDK, and C++ CMake tools for Windows. Run commands in a Developer PowerShell or Developer Command Prompt.
CMake 3.24 or newer.
Python 3 for Fabric registry generation. Disabling RHEA_GENERATE_TYPE_REGISTRY does not remove this requirement. The current top-level SDK also initializes the Fabric registry for renderer-only configurations, so Python is required there too.
Git to clone the repository and for Git-based dependency downloads.
Ninja only if you select a Ninja generator or the supplied Ninja presets.

Rhea does not install these tools. Verify availability with cmake --version, git --version, and a Python version command such as py -3 --version on Windows. If Python is installed but CMake cannot locate it, pass -DPython3_EXECUTABLE="C:/path/to/python.exe" when configuring.

Libraries and default behavior

Dependency	Required when	How it is obtained	Disable the feature
nlohmann/json	Always in the current top-level SDK configuration	Installed CMake package first; otherwise downloads the 3.12.0 archive	No top-level switch
SDL3	SDL backends are enabled; enabled by default	Installed CMake package first; otherwise downloads Git tag `release-3.4.12`	`RHEA_ENABLE_SDL=OFF`
Bullet	Engine physics and the Bullet implementation are enabled; both enabled by default	Installed package first (config, then CMake's FindBullet module); otherwise downloads Git commit `d3afe76132fc76b0f9b2359cbaef47a3766e7fbb`	`RHEA_BUILD_BULLET=OFF`; or disable all physics with `RHEA_BUILD_PHYSICS=OFF`
OpenSSL	TLS support is desired; lookup enabled by default	Installed package only; if missing, configuration continues with TLS disabled	`RHEA_ENABLE_OPENSSL=OFF`
GoogleTest	`RHEA_BUILD_TESTS=ON`, the default for a top-level build	Installed package lookup, with a download fallback to `v1.17.0`	`RHEA_BUILD_TESTS=OFF`
miniaudio, stb, tinygltf, tinyobjloader, glad	Their respective modules are built	Sources already included in the repository	Select the relevant modules/backends
libogg/libvorbis	Audio and Vorbis decoding are enabled; enabled by default	Sources included in the repository by default; external `Vorbis` package if `RHEA_AUDIO_USE_BUNDLED_VORBIS=OFF`	`RHEA_AUDIO_ENABLE_VORBIS=OFF`, or `RHEA_BUILD_AUDIO=OFF`

These are build-configuration requirements: even building only the BasicApp target can configure other enabled modules and resolve their dependencies. FetchContent downloads source at configure time and the dependency is subsequently built with the project. It does not install a system-wide package.

The listed versions describe download fallbacks, not version constraints on installed packages. See Third-party notices for licenses.

Turning SDL off requires a suitable alternative window/input backend for a graphical application. It is not a general solution for missing platform libraries. Fetching SDL source also does not install a graphics driver or Linux platform development packages.

Option A: let Rhea obtain missing libraries

From the SDK root:

cmake -S . -B out/basic-app -DRHEA_BUILD_APPS=OFF -DRHEA_BUILD_SAMPLES=ON -DPOSEIDON_BUILD_SAMPLES=OFF -DRHEA_BUILD_TESTS=OFF -DRHEA_FETCH_MISSING_DEPENDENCIES=ON -DCMAKE_BUILD_TYPE=Debug
cmake --build out/basic-app --config Debug --target Rhea_Sample_01_BasicApp

RHEA_FETCH_MISSING_DEPENDENCIES defaults to ON. Existing packages discoverable by CMake are preferred. Missing nlohmann/json, SDL3, and Bullet are fetched; missing OpenSSL is not. Network access and Git are needed for the source downloads. Downloaded source normally lives under the build directory's _deps directory.

Option B: provide installed packages and disable Rhea downloads

Set -DRHEA_FETCH_MISSING_DEPENDENCIES=OFF. Missing required packages then cause configuration to fail instead of being downloaded. This does not disable SDL, physics, or JSON support.

For installations outside CMake's normal search paths, supply a package-manager toolchain or -DCMAKE_PREFIX_PATH="C:/path/to/install-prefix". The prefix must contain the package configuration files, headers, and libraries, not merely downloaded source.

vcpkg: explicit installation (classic mode)

Use a standalone vcpkg checkout in a writable directory, for example C:/dev/vcpkg. If you already have one, skip the clone and bootstrap steps. The following commands are for Windows PowerShell:

git clone https://github.com/microsoft/vcpkg.git C:/dev/vcpkg
& C:/dev/vcpkg/bootstrap-vcpkg.bat
& C:/dev/vcpkg/vcpkg.exe install bullet3 sdl3 nlohmann-json openssl --triplet x64-windows-static-md --classic

The port names are bullet3, sdl3, and nlohmann-json; their CMake package names are Bullet, SDL3, and nlohmann_json. OpenSSL is included here to retain TLS support. It can be omitted if TLS is not needed.

Configure from the SDK root using a new build directory:

cmake -S . -B out/basic-app-vcpkg "-DCMAKE_TOOLCHAIN_FILE=C:/dev/vcpkg/scripts/buildsystems/vcpkg.cmake" -DVCPKG_TARGET_TRIPLET=x64-windows-static-md -DVCPKG_MANIFEST_MODE=OFF -DRHEA_FETCH_MISSING_DEPENDENCIES=OFF -DRHEA_BUILD_APPS=OFF -DRHEA_BUILD_SAMPLES=ON -DPOSEIDON_BUILD_SAMPLES=OFF -DRHEA_BUILD_TESTS=OFF -DCMAKE_BUILD_TYPE=Debug
cmake --build out/basic-app-vcpkg --config Debug --target Rhea_Sample_01_BasicApp

Use an x64 compiler environment when using this triplet. x64-windows-static-md selects static dependency libraries with the dynamic MSVC runtime, matching the usual MSVC runtime default. Other architectures and linkage choices need a matching triplet and compiler configuration. With shared libraries, required DLLs must also be available when running the sample.

VCPKG_MANIFEST_MODE=OFF explicitly selects the packages installed in classic mode. Set the toolchain and triplet on the first configure; use a new build directory when changing package source, toolchain, or triplet. vcpkg integrate install is not required for this explicit CMake toolchain workflow.

vcpkg: project-owned dependencies (manifest mode)

For a project that uses Rhea, maintain a vcpkg.json at that project's root, for example:

{
  "name": "my-rhea-app",
  "version-string": "0.1.0",
  "dependencies": ["bullet3", "sdl3", "nlohmann-json", "openssl"]
}

Configure that project with the vcpkg toolchain, a matching triplet, and RHEA_FETCH_MISSING_DEPENDENCIES=OFF. Leave manifest mode enabled. The toolchain installs manifest dependencies during configuration. Add a registry baseline to pin package resolution for reproducible releases, and commit the manifest and registry configuration.

The development workspace already has its own manifest and registry configuration. They are outside SDK/Rhea and are not part of a standalone engine checkout; do not rely on them being present for public builds.

Disabling Rhea downloads does not disable vcpkg downloads. In classic mode, install packages explicitly before configuring. In manifest mode, to prevent automatic installation during CMake configuration, set VCPKG_MANIFEST_INSTALL=OFF after preinstalling dependencies into the same manifest installation directory. A completely offline build also requires all necessary packages, tools, and caches to be available locally.

For details, see Microsoft's CMake integration and manifest tutorial.

Tools you install yourself​

Libraries and default behavior​

Option A: let Rhea obtain missing libraries​

Option B: provide installed packages and disable Rhea downloads​

vcpkg: explicit installation (classic mode)​

vcpkg: project-owned dependencies (manifest mode)​