Missing include files

I have an old project that uses OpenCV. I do not know which version. When I install the latest version (4.5.2) and try to compile it misses some includes. The install only seems to have the opencv2\opencv.hpp file inside the include folder. But this file tries to include other ones like opencv2/opencv_modules.hpp. That one is not present.
What am I doing wrong?
I’m using Windows 10, 64 bits, Visual Studio 2019.

what did you do, exactly ?

I downloaded the opencv-master from Githib, then I used CMake-gui to configure and generate.
CMake seems to do a lot, but the include files are not generated.

When downloading the prebuild version the include files are present. But then I’m stuck to Visual Studio 2017. I would like to use 2019.

cmake does a lot, but it only generates project files, it neither compiles or links anything

you have to open the generated opencv.sln, and build the INSTALL project

then, you have to use the headers from the install/include folder, not the ones from src

I know CMake does not compile and link. But it should generate the files inside the build folder, right?
Well, it generates files. But inside the include folder there is only the opencv.hpp file. While in the prebuild version there are a lot more include files in the include folder.

no. that’s what the INSTALL project does (with VS on win)

Aha, I didn’t know that. So I opened the opencv.sln file in the build. There are a lot of projects in there. I did a general run. But I still do not see the include dir with files and dll’s being generated. Do I have to run a specific project?
Can I run in Release mode? Because when doing this in Debug mode it complains about a missing python lib file.