SDL_GetRelativeMouseState - Retrieve the current state of the mouse
#include "SDL.h"
Uint8 SDL_GetRelativeMouseState(int *x, int *y);
The current button state is returned as a button bitmask, which can be
tested using the SDL_BUTTON(X) macros, and x and y are set to the
change in the mouse position since the last call to
SDL_GetRelativeMouseState or since event initialization. You can pass
NULL for either x or y.
SDL_GetMouseState