Designing Games with Game Maker - YoYo Games

oom.
room_tile_add(ind,back,left,top,width,height,x,y,depth) Adds
a new tile to the room at the indicate position. It returns the index of the tile.
back is the background from which the tile is taken. left, top, width and height
indicate the part of the background that forms the tile. x,y is the position of
the tile in the room and depth is the depth of the tile.
room_tile_add_ext(ind,back,left,top,width,height,x,y,depth,
xscale,yscale,alpha) Same as the previous routine but this time you can
also specify a scaling factor in x and y direction and an alpha transparency for
the tile.
room_tile_clear(ind) Removes all tiles from the indicated room.
Files, registry, and executing programs
In more advanced games you probably want to read data from a file that you provide with the
game. Or you might want to store information between runs of the game. And in some
situations you might need to execute external programs.
Files
It is useful to use external files in games. For example, you could make a file that describes at
what moments certain things should happen. Also you probably want to save information for
the next time the game is run (for example, the current room). The following functions exist to
read and write data in text files:
file_text_open_read(fname) Opens the file with the indicated name for
reading. The function returns the id of the file that must be used in the other
functions. You can open multiple files at the same time (32 max). Don't forget
to close them once you are finished with them.
file_text_open_write(fname) Opens the indicated file for writing,
creating it if it does not exist. The function returns the id of the file that must
be used in the other functions.
file_text_open_append(fname) Opens the indicated file for appending
data at the end, creating it if it does not exist. The function returns the id of
the file that must be used in the other functions.
file_text_close(fileid) Closes the file with the given file id.