SDL_GetWindowOpacity - Man Page

#include <SDL3/SDL_video.h>

float SDL_GetWindowOpacity(SDL_Window *window);

If transparency isn't supported on this platform, opacity will be returned as 1.0f without error.

window

the window to get the current opacity value from.

for more information.

This function should only be called on the main thread.

This function is available since SDL 3.2.0.

SDL_SetWindowOpacity(3)

SDL_SetWindowOpacity(3).