it would be possible, but depending on your goals, you will sooner or later want to have a full checkout of the repository, and a corresponding build environment.
At least on Linux, scripted compilation should get you going pretty quickly (if you have the bandwidth).
Another option would be a docker container with a pre-downloaded environment, possibly including pre-built binaries and checked out source trees, analogous to this:
http://wiki.flightgear.org/Howto:Buildi ... via_DockerWalking you through the process of manually building via g++ would be comparatively tedious in my opinion, cmake is not complicated to use.
All that is needed is actually documented in the wiki, and it can be automatically handled by the build script.
cmake will really just need to be configured once, at which point it will create unix makefiles (on Linux), which will in turn invoke g++, while handing dependencies and platform differences.
Obviously, if you want to take things step by step, you could start with a trivial "hello world" style example using just cmake, and then take it from there.
You could start really simple by looking for "demo" (example) projects covering cmake and g++, for example:
https://github.com/qedsoftware/cmake-demoI suppose, youtube will also have dozens of videos walking you through the details of setting up a simple cmake project from scratch, i.e. with your background, that should not take you much more than 20-30 minutes to work through, at which point you'll know the basics, and should be able to make heads and tails of simgear/flightgear and its cmake build system:
https://www.youtube.com/results?search_ ... ke+c%2B%2BFor the flightgear specifics, I would refer you to the wiki (search for cmake)
Again, covering flightgear/simgear stuff at this time doesn't make much sense until you have built some basic "hello world"-style programs first.
The other really useful prerequisite is obviously some basic familiarity with git, which you can also get by referring to github/youtube respectively.
I would suggest to only look at fg specifics once git&cmake are sufficiently familiar - and again, our docs are pretty good in that regard actually (wiki), and who knows, maybe you'll even consider getting involved in improving our wiki docs along the way ?