关于 SDL_CreateRGBSurface的

函数原型：
SDL_Surface *surface; Uint32 rmask, gmask, bmask, amask; /* SDL interprets each pixel as a 32-bit number, so our masks must depend on the endianness (byte order) of the machine */#if SDL_BYTEORDER == SDL_BIG_ENDIAN rmask = 0xff000000; gmask = 0x00ff0000; bmask = 0x0000ff00; amask = 0x000000ff;#else rmask = 0x000000ff; gmask = 0x0000ff00; bmask = 0x00ff0000; amask = 0xff000000;#endif surface = SDL_CreateRGBSurface(0, width, height, 32, rmask, gmask, bmask, amask); if(surface == NULL) { fprintf(stderr, "CreateRGBSurface failed: %s\n", SDL_GetError()); exit(1); }
什么 SDL_CreateRGBSurface（）要有rmask, gmask, bmask, amask; 4个参数，
这些参数不是没用吗？
这4个都要用0再可以，或者上面那总，