Provided by: libsdl3-doc_3.2.20+ds-2_all 

NAME
SDL_GetDirect3D9AdapterIndex - Get the D3D9 adapter index that matches the specified display.
SYNOPSIS
#include <SDL3/SDL_system.h>
int SDL_GetDirect3D9AdapterIndex(SDL_DisplayID displayID);
DESCRIPTION
The returned adapter index can be passed to IDirect3D9::CreateDevice and controls on which monitor a full
screen application will appear.
FUNCTION PARAMETERS
displayID
the instance of the display to query.
RETURN VALUE
for more information.
AVAILABILITY
This function is available since SDL 3.2.0.
Simple Directmedia Layer SDL 3.2.20 SDL_GetDirect3D9AdapterIndex(3)