i) do i set up a whole new build folder using cmake, if so which generator do you recommend.
ii) or can i use the old one with the cmake cache generated for eclipse
iii) if (i) is there an easy way to re-use the cmake cache settings from the old eclipse build eg ffmpeg libraries.
I have not tried this yet but I know a few things about cmake.
You can create a new folder/directory i.e. cmakebuildqt and go in there.
If you type cmake command, choose the generator, and set the source path you will be able to generate the project.
e.g. cmake -G “…” ./…
The generator must be one for QT and the source path will be the parent folder (because now you are in cmakebuildqt)
Perhaps it will not be a good idea, you could generate it from scratch.
after, from buid directory generate QTCreator project files using the qtcreator script into blender build_files directory: python3 …/blender/build_files/cmake/cmake_qtcreator_project.py