RPG Maker XP Event Triggers Explained

There are four supported triggers for events in Enterbrain's RPG Maker XP engine: Action Button, Player Touch, Event Touch, Autorun, and Parallel Process. These triggers regulate when the scripted event code for that event will begin to run. Here is a brief summary of how they each work.

Action Button
If an event is set to trigger in reponse to the action button, this means it will occur if the player's avatar is standing next to the event, facing it, and press the action button (by default, the enter key). Most visible events in the game will use this trigger. It is the trigger for nonplayer characters (NPCs) and treasure chests.

Player Touch
Player touch events are similiar to action button events, however, rather than require that the player press the enter key, they will happen as soon as the player steps into the event's locations (or attempts to step there, if the event is impassible). A possible use for these types of events would be landmines. You would not want a player to volunteer to be hit by a landmine, so RPG Maker XP allows you trigger a landmine event as soon as the player enters the mined location.

Event Touch
Event touch is the same as the player touch, except in reverse. Player touch events are triggered when the player attempts to move into an event. Event touch events are triggered when an event attempts to move into a player, in addition to those instanes where a player runs into the event. A good example of an event touch event may be a pick pocket NPC who, upon walking into the player, says "Excuse me." and reduces the party's gold by 10.

Autorun and Parallel Process
Besides player touch and event touch, the distinction between autorun and parallel process is something that gives new RPG Maker XP users some trouble. Both autorun and parallel process will begin as soon as a player enters the map and continue until they either end or the player leaves the map. Autorun will completely stop the game (like other events) until it's script has finished. It's a great way to begin scripted cutscenes as soon as a player enters a map. It can also be used to perform cutscenes across multiple maps, as described in the multimap cutscene tutorial.

A parallel process, on the other hand, will allow the game to continue to run while it executes its script. It is a good choice for timed background effects, such as flashes of lightning or flocks of birds that fly across the screen. One important thing to remember about parallel processes is that, compared to other events, they consume a great amount of CPU time, so having more a couple of parallel process events on a given map is usually a bad idea.