While the window has focus and relative mouse mode is enabled, the cursor
is hidden, the mouse position is constrained to the window, and SDL will
report continuous relative mouse motion even if the mouse is at the edge of
the window.
If you'd like to keep the mouse position fixed while in relative mode you
can use SDL_SetWindowMouseRect(). If you'd like the cursor to be at a
specific location when relative mode ends, you should use
SDL_WarpMouseInWindow() before disabling relative mode.
This function will flush any pending mouse motion for this window.
Set relative mouse mode for a window.
While the window has focus and relative mouse mode is enabled, the cursor is hidden, the mouse position is constrained to the window, and SDL will report continuous relative mouse motion even if the mouse is at the edge of the window.
If you'd like to keep the mouse position fixed while in relative mode you can use SDL_SetWindowMouseRect(). If you'd like the cursor to be at a specific location when relative mode ends, you should use SDL_WarpMouseInWindow() before disabling relative mode.
This function will flush any pending mouse motion for this window.