How do I make vcpkg use the pre-installed Qt library instead of building it?

[SineStriker]

I have installed the Qt 5.15.2 via Qt official installer, and it's at the root path of drive C.

When I want to use vcpkg to install a library which depends on Qt, vcpkg will download and build qt-base first. How to let vcpkg know that there's an existing Qt library and use it.

[Osyotr]

https://devblogs.microsoft.com/cppblog/using-system-package-manager-dependencies-with-vcpkg/#using-curl-and-openssl-from-the-system-package-manager

[SineStriker]

Thanks, but it's not over. I add an simple vcpkg.json and portfile.cmake into a custom directory and pass it as overlay-ports to vcpkg install command, and then cmake cannot find Qt5Config.cmake...

How to pass an env such as Qt5_DIR to cmake via portfile.cmake?

[Osyotr]

https://github.com/microsoft/vcpkg/blob/master/docs/users/triplets.md#vcpkg_env_passthrough_untracked

[SineStriker]

https://github.com/microsoft/vcpkg/blob/master/docs/users/triplets.md#vcpkg_env_passthrough_untracked

Thanks so much.

[SineStriker]

set(ENV{Qt5_DIR} "/path/to/"

I think this is better.

[LilyWangLL]

Thanks for Osyotr's help. Since this issue has been resolved, so I am closing this issue for now.

[rockydut]

Can you list detailed implementation steps? QT is already installed, and external QT is used in vcpkg instead of recompilation.
My system is windows.

[rockydut]

@LilyWangLL Can you list detailed implementation steps? QT is already installed, and external QT is used in vcpkg instead of recompilation.
My system is windows.