#include <SDL.h> or #include <SDL3/SDL.h>?
#include <SDL.h> or #include <SDL3/SDL.h>?The most portable way to include SDL headers is to use angular quotes around the full header name:
#include <SDL3/SDL.h>This is new in SDL3! Previously, in SDL2, we recommended #include "SDL.h", but this proved to be unfriendly to macOS frameworks and having the API version in the include line is useful for making dependency requirements clear.
SDL provides the lower level of functionality that a cross-platform game engine needs, leaving higher level tasks to other libraries. The libraries page has a non-exhaustive list of libraries that are known to work well with SDL.
No, most graphics back ends are not thread-safe, so you should only call SDL video functions from the main thread of your application. SDL_RunOnMainThread() can be used to dispatch code that needs to run on the main thread.
The main event handling should be done on the main thread, though you can use SDL_PushEvent() and SDL_PeepEvents() to interact with the event queue on other threads. Most SDL functions have their thread-safety noted in their documentation.
No, there are many different ways to use shaders, and rather than restrict you to a subset of shader functionality, we recommend using a full 3D API like SDL GPU. You can look at how SDL uses the GPU API for 2D rendering if you'd like to expand on that: SDL_render_gpu.c