Am looking at the repo for SuperTux as featured here in https://news.ycombinator.com/item?id=39528726 and trying to understand how the cross platform aspect works. Am I correct in my thoughts that it's OpenGL based, using a cross platform library called Simple DirectMedia Layer aka SDL, found at https://www.libsdl.org?I see a frequently occurring header file called SDL.h, but when I search the repo at https://github.com/SuperTux/supertux I can't find it.
What is SDL.h and why am I unable to locate it?
EDIT: /u/JohnFen pointed me in the right direction! https://news.ycombinator.com/item?id=39531202