Get the additional alpha value used in blit operations.
int SDL_GetSurfaceAlphaMod(SDL_Surface * surface, Uint8 * alpha);
|surface||the SDL_Surface structure to query|
|alpha||a pointer filled in with the current alpha value|
Returns 0 on success or a negative error code on failure; call SDL_GetError() for more information.
This function is available since SDL 2.0.0.