the horizontal coordinate, 0 <= x < width.
the vertical coordinate, 0 <= y < height.
a pointer filled in with the red channel, normally in the range 0-1, or NULL to ignore this channel.
a pointer filled in with the green channel, normally in the range 0-1, or NULL to ignore this channel.
a pointer filled in with the blue channel, normally in the range 0-1, or NULL to ignore this channel.
a pointer filled in with the alpha channel, normally in the range 0-1, or NULL to ignore this channel.
true on success or false on failure; call SDL_GetError() for more information.
Retrieves a single pixel from a surface.
This function prioritizes correctness over speed: it is suitable for unit tests, but is not intended for use in a game engine.