The Sentinel Engine is a game engine being written in C++ on top of the SDL2 framework as a part of Project Sanctuary. It is currently not complete, but there are a number of tests available as well as the source code to peruse.
DISCLAIMER: We are currently targeting OSX, Linux, and Windows, so, if you're not on one of those platforms, we can't promise that the project will compile or run for you at all.
The first step is to make sure you have CMake installed. You can download and install CMake by following the instructions on their website. Alternatively, Visual Studio has the option to install CMake support directly in the IDE if this fits your workflow better.
For Linux and Mac you now need to make sure SDL2 is installed. On most linux distros, you can use your favorite package manager to install the SDL development libraries (note, this is not the same as the source libraries). This might look something like:
apt-get install libsdl2-dev
On Mac you can alternatively use the .dmg to install SDL2 from their website. It's preferable to place the contents under ~/Library/Frameworks.
At this point, you can just run the following commands:
cd <your>/<path>/<to>/Sentinel
cmake ./
make
And congrats you've done, Sentinel has now compiled. Alternatively, if you want to keep your root directory clean, you can instead run this set of commands:
cd <your>/<path>/<to>/Sentinel
mkdir build
cd build
cmake ../
make
As with most things in development though, if you're on windows, life gets a bit harder. SDL pretty much just gives you a zip file and tells you to figure out, so you need to follow the following steps for CMake to find SDL properly.
For SDL you want to download the SDL2 development libraries (not the source code) from the website. From there, you should extract from inside the zip archive a folder called SDL2-<version> to the directory Sentinel/lib directory (if it does not exist, go ahead and create it now. Note that the word lib is case-sensitive.). The part is whatever version of SDL you happened to download (though the minimum required version is SDL2-2.0.0) You should now rename this folder from SDL2-<version> to SDL2.
From there, you have to go into the folder Sentinel/extras and copy the file sdl2-config.cmake into the SDL2 directory we just made.
Finally, to make sure that your program can link at runtime to the SDL2 library, if you are targeting a 64-bit architecture, you need to go into the folder Sentinel/SDL2/lib/x64 and copy the file SDL2.dll into C:\Windows\System32 directory to finish the install. Alternatively, if you are compiling to target 32-bit architecture instead of the 64-bit version, you should instead go into the folder Sentinel/SDL2/lib/x86 and copy the file SDL2.dll from that folder into the folder C:\Windows\SysWOW64. (I know it seems counter-intuitive to put the 64-bit version in System32 and the 32-bit version makes it into SysWOW64. That's not a typo, it's just how Windows is... sigh).
Now you're safe to run the CMake build from the root Sentinel Directory, and start hacking away. If you're using VisualStudio, you can reload CMake by hitting Ctrl+s in the root CMakeLists.txt file.