A Trigger is the basis of any action that happens in a Scene, consisting of a series of commands stating "When X happens, if Y is true, do Z, otherwise do N". Triggers consist of all the "If - then" statements that make up the actions in a Scene. Triggers dictate things such as when and if a player can interact with a Prop and what happens when they do, what happens when something enters a Region, the outcome and circumstances that start and finish Events, and the starting, updating, and finishing of Goals.
By default all triggers fire once. Use the retain trigger check box at the top of the Scene Data Window to have that trigger keep firing. Trigger retaining can also be controlled by triggers.
Triggers Reference for a list of triggers
Triggers can be created from the Scene Data view. From this view you have two options:
In order to rename your trigger, double click the newly created trigger and give it a name. Upon selecting a trigger, a properties window will appear to the right that contains information about that trigger. This is where the magic happens.
Preset Values exist as modifiers for specific when, if, do, otherwise options, and are usually used to clarify a specific state of being, such as if something is True or False. The preset values that are available differ depending on what has been selected, but they are used to clarify what it is the user is trying to do. For example, if the user wants to set up a trigger that will allow the player to turn off the alarm system, but only if the alarm is not already going, then their If statement would read like:
If the Alarm is not active
The preset value in this instance is the "is not" part of the the statement, and could just as easily be changed to "is" if the user wanted the opposite effect. Preset Values can be found in any of the Trigger tabs, and will change depending on the selected action.
When a Trigger wants to interact with a prop directly, it needs to be told which prop it is supposed to be cooperating with. If a Trigger option has an existing items drop down list, then it is designed to work with props.
For example, the When statement On Item Interaction will default to:
When Nothing Selected is interacted with:
The user will have to specify which item is being interacted with by right clicking on the underlined section and selecting an item from the drop down list presented. If there are no interactable objects in the scene, the option will not be available.
Quick Start Guide 2 - Creating Triggers with Goals and Regions