SDL_MapRGB- Map a RGB color value to a pixel format.
Uint32 SDL_MapRGB(SDL_PixelFormat *fmt, Uint8 r, Uint8 g, Uint8 b);
Maps the RGB color value to the specified pixel format and returns the pixel
value as a 32-bit int.
If the format has a palette (8-bit) the index of the closest matching color in
the palette will be returned.
If the specified pixel format has an alpha component it will be returned as all
1 bits (fully opaque).
A pixel value best approximating the given RGB color value for a given pixel
format. If the pixel format bpp (color depth) is less than 32-bpp then the
unused upper bits of the return value can safely be ignored (e.g., with a 16-bpp
format the return value can be assigned to a Uint16, and similarly a Uint8 for
an 8-bpp format).
SDL_GetRGB, SDL_GetRGBA, SDL_MapRGBA, SDL_PixelFormat
So, now you have your screen surface, and have loaded a couple bitmaps. And are
ready to animate. In order to prepare to draw, you probably want to write some
type of background(could be a bitmap), or simply fill the screen with a fixed
color. SDL doesn't have a "Clear Screen" function, but, it does provide a method
of setting an entire surface to one color.
Recall, the function SDL_MapRGB can be used to determine a color value from a
RGB group. The parameters to SDL_MapRGB are the format substructure of the
Surface you wish to fill, and then the Red, Green, and Blue values respectively.
SDL_FillRect will fill a surface with a color. This function takes three
parameters: the surface to fill, a SDL rectangle structure pointer, and an
integer color. If the structure pointer passed to the function is NULL, the
entire surface is filled.