Classic mode
============

`vcpkg classic mode`_ is less recommended than `vcpkg manifest mode`_
but remains a solid approach to compile Rat C++ libraries with vcpkg_.

It allows to install packages globally using the local vcpkg
repository which has been bootsrapped during the previous
:doc:`setup` section. All binaries then reside in this directory
and all projects can share this same installation.

`vcpkg classic mode`_ however does not allow precise versioning of
the packages to compile and install, unlike `vcpkg manifest mode`_.

Consume packages
----------------

Using `vcpkg classic mode`_ the idea is to exposes `rat-vcpkg/ports`_
as **overlays** by passing the ``--overlay-ports=ports`` flag to the
install command to make vcpkg_ aware of these port definitions.

vcpkg_ solves dependencies quite neatly so one can try to install
``rat-models`` using the desired `vcpkg triplet`_ to get the whole
dependency chain started.

.. warning::

    VTK ports recently changed to introduce a ``vtk-compile-tools``
    port which is host specific and might break CMake_ configuration.

    To fix this, ensure the ``vtk-compile-tools`` package is
    installed in **global vcpkg using classic mode** by running the
    following command from outside the current manifest project:

    ``vcpkg install vtk-compile-tools``

- Clone the Rat-vcpkg_ repository:

.. code-block:: powershell

    git clone https://gitlab.com/project-rat-extras/rat-vcpkg.git

- Run the following command from within
  the cloned Rat-vcpkg_ repository:

.. code-block:: powershell

    # Need to point to local Rat-vcpkg ports directory
    vcpkg install rat-models:x64-windows-release --overlay-ports=ports --clean-after-build

    # or if one needs to keep the buildtrees for debugging purposes
    vcpkg install rat-models:x64-windows-release --overlay-ports=ports

.. note::

    Depencies might take some time to build depending on the
    hardware.

    The heaviest one for Rat seems to be VTK, which is even
    longer to build in ``Debug``.

This will install packages in the local vcpkg repository.

- Ensure the ``VCPKG_ROOT`` environment variable is defined and
  points to the local vcpkg repository installation.

- Configure a CMake_ project using the vcpkg toolchain file:

.. code-block:: powershell

    cd myproject
    cmake -B build -S . -G "Ninja" `
        -DCMAKE_BUILD_TYPE="Release" `
        -DCMAKE_TOOLCHAIN_FILE="$env:VCPKG_ROOT\scripts\buildsystems\vcpkg.cmake" `
        -DVCPKG_TARGET_TRIPLET="x64-windows-release" `
        -DVCPKG_HOST_TRIPLET="x64-windows-release"

- Build the project:

.. code-block:: powershell

    cmake --build build

.. Links
.. _CMake: https://cmake.org
.. _Project-Rat: https://gitlab.com/project-rat
.. _Rat-Docs: https://gitlab.com/project-rat/rat-documentation
.. _Rat-vcpkg: https://gitlab.com/project-rat-extras/rat-vcpkg
.. _rat-vcpkg/ports: https://gitlab.com/project-rat-extras/rat-vcpkg/-/tree/main/ports?ref_type=heads
.. _vcpkg: https://vcpkg.io/en/
.. _vcpkg binary caching: https://learn.microsoft.com/en-us/vcpkg/users/binarycaching
.. _vcpkg classic mode: https://learn.microsoft.com/en-us/vcpkg/concepts/ports
.. _vcpkg manifest mode: https://learn.microsoft.com/en-us/vcpkg/consume/manifest-mode?tabs=msbuild%2Cbuild-MSBuild
.. _vcpkg ports: https://learn.microsoft.com/en-us/vcpkg/concepts/ports
.. _vcpkg triplet: https://learn.microsoft.com/en-gb/vcpkg/concepts/triplets