SDL_IsMainThread - Return whether this is the main thread.

       This function is available since SDL 3.2.0.

       On  Apple  platforms, the main thread is the thread that runs your program's main() entry point. On other
       platforms, the main thread is the one that calls SDL_Init([SDL_INIT_VIDEO](SDL_INIT_VIDEO)), which should
       usually be the one that runs your program's main() entry point. If you  are  using  the  main  callbacks,
       SDL_AppInit(), SDL_AppIterate(), and SDL_AppQuit() are all called on the main thread.

       SDL_IsMainThread - Return whether this is the main thread.

       Returns true if this thread is the main thread, or false otherwise.

SDL_RunOnMainThread(3)

Simple Directmedia Layer                           SDL 3.2.20                                SDL_IsMainThread(3)

#include<SDL3/SDL_init.h>boolSDL_IsMainThread(void);

       It is safe to call this function from any thread.