# SDL_GetSurfaceAlphaMod Get the additional alpha value used in blit operations. ## Header File Defined in [<SDL3/SDL_surface.h>](https://github.com/libsdl-org/SDL/blob/main/include/SDL3/SDL_surface.h) ## Syntax ```c bool SDL_GetSurfaceAlphaMod(SDL_Surface *surface, Uint8 *alpha); ``` ## Function Parameters | | | | | ---------------------------- | ----------- | -------------------------------------------------- | | [SDL_Surface](SDL_Surface) * | **surface** | the [SDL_Surface](SDL_Surface) structure to query. | | Uint8 * | **alpha** | a pointer filled in with the current alpha value. | ## Return Value (bool) Returns true on success or false on failure; call [SDL_GetError](SDL_GetError)() for more information. ## Thread Safety It is safe to call this function from any thread. ## Version This function is available since SDL 3.2.0. ## See Also - [SDL_GetSurfaceColorMod](SDL_GetSurfaceColorMod) - [SDL_SetSurfaceAlphaMod](SDL_SetSurfaceAlphaMod) ---- [CategoryAPI](CategoryAPI), [CategoryAPIFunction](CategoryAPIFunction), [CategorySurface](CategorySurface)