Designing Games with GameMaker

Actions

Actions indicate the things that happen in a game created with GameMaker. Actions are placed in events of objects. Whenever the event takes place these actions are performed, resulting in certain behavior for the instances of the object. There are a large number of different actions available and it is important that you understand what they do. In this chapter we describe the actions available in simple mode. Note that a number of these actions are only available in the Standard Edition of GameMaker. This will be indicated.

All the actions are found in the tabbed pages at the right of the object property form. There are six sets of actions. You select the set you want by clicking on the correct tab. When you hold you mouse above one of the actions, a short description is shown to remind you of its function.

Let us briefly repeat: To put an action in an event, just drag it from the tabbed pages to the action list. You can change the order in the list, again using dragging. Holding the <Alt> key while dragging makes a copy of the action. (You can drag and copy actions between the lists in different object property forms.) Use the right mouse button and select the correct menu item to remove actions (or use the <Del> key) and to copy and paste selected actions.

When you drop an action in the action list, a window will pop-up most of the time, in which you can fill in certain parameters for the action. The parameters will be described below when describing the actions. Two types of parameters appear in many actions so we will describe these here. At the top you can indicate to which instance the action applies. The default is self, which is the instance for which the action is performed. Most of the time, this is what you want. In the case of a collision event, you can also specify to apply the action to the other instance involved in the collision. For instance, in this way you can destroy the other instance. Finally, you can choose to apply the action to all instances of a particular object. In this way you could change all red balls into blue balls. The second type of parameter is the box labeled Relative. By checking this box, the values you type in are relative to the current values. For example, in this way you can add something to the current score, rather than changing the current score to the new value. The other parameters will be described below. You can later change the parameters by double clicking on the action.

Information on the different actions can be found in the following pages: