UnrealEd 2.0 Mapping Basics - Triggers

Now we're going to create a door - to do that we will create a Mover and we will use a Trigger to activate it.

After creating another mover and setting up its movement using the previously explained method we will have to change some properities. Since we want a door (you can of course add two movers that open in opposite directions or even more complex doors with several pieces that slide in different directions) we have to make it open before a player touches it (otherwise it will break the flow), so we have to change the InitialState to either TriggerControl or TriggerOpenTimed.

Now we have to add another actor, a Trigger. You can find it in the Actor Browser under the Triggers category. It's better to add in in the middle of the door (at floor

level), or in the middle of the doorframe if we have more movers.

A Trigger is an object that generates an Event (activates something) when something (generally a player) enters in its radius. We will set up the door to open when a

player enters in the Trigger's radius.

We can change the Trigger's radius altering the parameters CollisionHeight and CollisionRadius in its Actor properities, under Collision (pretty much self-explaining). You

can check the radius in the viewports with the Actor > Radii View mentioned before.

Let's also give an Event to the Trigger, which is basically what will happen when a player will step inside the TriggerRadius. To do so you just have to write something

(for example "MyLittlePrettyDoor") instead of None in the Event field under Events.

Now we have to link the Trigger to our door(s), so enter the Actor Properities of the Mover and write the name chosen before for the Trigger's Event (in this case

"MyLittlePrettyDoor") into the Tag field under Events. A red line will appear between the two objects, confirming you that they're linked. The red line is visible only in

the 2D viewports and in Wireframe mode.

Now when someone will step in the Trigger all the objects with the chosen Tag (in this case "MyLittlePrettyDoor") will be activated. If we had a door with multiple pieces

(multiple movers sliding in different directions) we will of course have to assign the same Tag to all these Movers. And of course if you plan to have more than one door

in your map you have to use different Events, otherwise when you will touch one Trigger all the doors of the level will open at the same time.

Maybe you're wondering what's the difference between TriggerOpenTimed and TriggerControl (the InitialState of the movers): choosing TriggenOpenTimed will make your door open, then it will stay open for the whole StayOpenTime that you set in the Mover properities and then it will close, ignoring players. With TriggerControl instead the Mover will ignore the StayOpenTime and will always stay open while there is a player in the Trigger's radius.

Usually it's better to use a TriggerControl, since a door will almost never close while you're trying to pass under it (it still can screw up sometimes when there are

multiple players in the area).

Try to place the Trigger carefully - it should allow players to travel comfortably through the door from every location without bumping in it. It's also better to always

set a ReTriggerDelay of 0.1 or less in the Trigger properities (under Trigger), so if a door will close in front of a player who was trying to go through it the trigger

will restart almost immediately (without ReTriggerDelay the player would have to exit the trigger radius and re-enter it to activate it).

There are many possible settings for Movers and Triggers - try to play around with them and you should get the hang of Movers pretty quickly. The Event and Tag options are available for every actor, but they act differently (most of the actors do nothing when triggered). Experimenting is the best way to learn, although it takes time.

18. Conclusion

00. Back to Start