Designing Games with Game Maker - YoYo Games

ehavior we must define events for the object. You can only add code actions
to events. You need to specify the object, the event type, the event number
(use the constants that have been specified before for the event_perform()
function). Finally you provide the code string that must be executed. You can
add multiple code actions to each event.
object_event_clear(ind,evtype,evnumb) You can use this function to
clear all the actions for a particular event.
Creating objects is in particular useful when you are designing scripts or action libraries. For
example, an initialization script can create an object to display a text and another script can
add such an object with a particular text. In this way you have a simple mechanism to display
texts without the need to create objects using the standard interface.
Rooms
Manipulating rooms on the fly is a dangerous thing to do. You have to realize that rooms
change all the time due to what is happening in the game. This normally only involves the
currently active room and there are many routines described in previous sections to
manipulate the instances, backgrounds, and tiles in the active room. But changes in the active
room will last if the room is persistent. Hence, you should never manipulate aspects of the
currently active room or any room that is persistent and that has already been visited before.
Such changes in general won't be noticed but might sometimes even lead to unexpected
errors. Due to the fact that rooms are linked in a complicated way there is also no routine to
delete a room.
The following routines are available
room_set_width(ind,w) Sets the width for the room with the indicated
index.
room_set_height(ind,h) Sets the height for the room with the indicated
index.
room_set_caption(ind,str) Sets the caption for the room with the
indicated index.
room_set_persistent(ind,val) Sets whether the room with the indicated
index is persistent or not.
room_set_code(ind,str) Sets the initialization code string for the room