Surfaces are an incredibly powerful graphic tool that
GameMaker: Studio provides you for creating special effects
and a whole host of other things. They are relatively simple to use
as they are basically a canvas that you draw to instead of the
display screen, and this canvas can then be manipulated and changed
before being drawn with the functions on this page. For more
information on how to create surfaces, draw to them, and the
drawbacks associated with their use, please see the section on
Surfaces.
NOTE: When working with surfaces there is the possibility
that they can cease to exist at any time due to them being stored
in texture memory. You should ALWAYS check that a surface
exists using surface_exists
before referencing them directly. For further information see
Surfaces.
The following functions exist to deal with surfaces