Designing Games with Game Maker - YoYo Games

the keys pressed happen. Note that the keys on the numeric keypad only produce the
corresponding events when is pressed.
Mouse events
A mouse event happens for an instance whenever the mouse cursor lies inside the sprite
representing the instance. Depending on which mouse buttons are pressed you get the no
button, left button, right button, or middle button event. The mouse button events are
generated in each step as long as the player keeps the mouse button pressed. The press
events are only generated once when the button is pressed. The release events are only
generated when the button is released. Note that these events only occur when the mouse is
above the instance. If you want to react to mouse press or release events at an arbitrary
place, use the global mouse events that can be found in a submenu. There are two special
mouse events. The mouse enter event happens when the mouse enters the instance. The
mouse leave event happens when the mouse leaves the instance. These events are typically
used to change the image or play some sound. Mouse wheel up and mouse wheel down events
happen when the user moves the mouse wheel. Finally there are a number of events related
to the joystick. You can indicate actions for the four main directions of the joystick (in a
diagonal direction both events happen). Also you can define actions for up to 8 joystick
buttons. You can do this both for the primary joystick and the secondary joystick.
Other events
There are a number of other events that can be useful in certain games. They are found in this
menu. The following events can be found here:
• Outside: This event happens when the instance lies completely outside the room. This
is typically a good moment to destroy it.
• Boundary: This event happens when the instance intersects the boundary of the
room, that is, it lies (at least) partially outside the room.
• Views: Here you find a number of events that are useful when you use views in your
rooms. These events test whether the instance lies completely outside a particular
view or interesects the view boundary.
• Game start: This event happens for all instances in the first room when the game
starts. It happens before the room start event (see below) but after the creation
events for the instances in the room. This event is typically defined in only one
"controller" object and is used to start some background music and to initialize some
variables, or load some data.