# SDL_GetWindowOpacity Get the opacity of a window. ## Header File Defined in [<SDL3/SDL_video.h>](https://github.com/libsdl-org/SDL/blob/main/include/SDL3/SDL_video.h) ## Syntax ```c float SDL_GetWindowOpacity(SDL_Window *window); ``` ## Function Parameters | | | | | -------------------------- | ---------- | ------------------------------------------------- | | [SDL_Window](SDL_Window) * | **window** | the window to get the current opacity value from. | ## Return Value (float) Returns the opacity, (0.0f - transparent, 1.0f - opaque), or -1.0f on failure; call [SDL_GetError](SDL_GetError)() for more information. ## Remarks If transparency isn't supported on this platform, opacity will be returned as 1.0f without error. ## Thread Safety This function should only be called on the main thread. ## Version This function is available since SDL 3.2.0. ## See Also - [SDL_SetWindowOpacity](SDL_SetWindowOpacity) ---- [CategoryAPI](CategoryAPI), [CategoryAPIFunction](CategoryAPIFunction), [CategoryVideo](CategoryVideo)