int alpha = (int) (alpha_factor * 256);
SDL_Surface *dst = SDL_CreateRGBSurface(src->flags, src->w, src->h, src->format->BitsPerPixel, src->format->Rmask, src->format->Gmask, src->format->Bmask, src->format->Amask);
int bpp = dst->format->BytesPerPixel;
int alpha = (int) (alpha_factor * 256);
SDL_Surface *dst = SDL_CreateRGBSurface(src->flags, src->w, src->h, src->format->BitsPerPixel, src->format->Rmask, src->format->Gmask, src->format->Bmask, src->format->Amask);
int bpp = dst->format->BytesPerPixel;