Triggering Emitters

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Purpose

    This tutorial was created because of the multiple times this question has come up on the BuF mapping forum.  It will walk you through creating an emitter that can be triggered, step-by-step, with pictures.

Tutorial

  1. Open UnrealEd.
  2. Subtract a cube.

    3.    Place an emitter.

  • Emitters can be found in the Actor Browser: expand Actor if it isn't already expanded, and choose Emitter (don't expand it, just click the word).  It should be the fourth item down.
  • You can set the properties however you want; for the purpose of this tutorial, you just need to be able to see whether the emitter is working or not.  Refer to the UnrealWiki for more information on Emitters; if you just want to get through this tutorial, you can use a preset emitter.  You will find many of them if you expand the Emitter class.  If you choose this method, test the Emitter in Realtime Preview to ensure that it stays on and is not simply a temporary, one-time effect.

    4.    Place a trigger.

  • Triggers can be found in the Actor Browser toward the bottom; expand Triggers and choose Trigger.

    5.    Set the trigger's properties as follows:

  • Events>Event=TriggerEmitter
  • Advanced>bHidden=False
  • Ensure that the Trigger>TriggerType is set to TT_PlayerProximity

    6.    Set the emitter's properties as follows (Note that emitter properties are found under the Emitter actor's properties>Emitters>Emitter0):

  • Events>Tag=TriggerEmitter
  • Trigger>TriggerDisabled=True
  • Local>Disabled=True    OR    Spawning>AutomaticInitialSpawning=False
  • If you want the emitter to spray out its particles, then stop, set Local>RespawnDeadParticles=False.
  • Optional fields include Trigger>SpawnOnTriggerPPS and Trigger>SpawnOnTriggerRange>Min/Max.  The number entered in the SpawnOnTriggerPPS field will determine how many particles are immediately spawned and active when the emitter becomes active.  SpawnOnTriggerRange does the same, only it randomly chooses a number between the Min and Max settings.

    7.    Add a playerstart.  Rebuild, save, and test.

 

Explanation

Here's what we did:

  • After placing the actors, we told the trigger to send out the event TriggerEmitter when a player comes within its CollisionRadius.  We set it to be visible in-game so it would be easy to find and activate for the example.
  • Next, we told the emitter to listen for the event TriggerEmitter.  Before receiving this event, we set it to be disabled when the game starts, as well as to be enabled by a trigger.

Note: the Tag and Event that we used, TriggerEmitter, can be set to anything as long as they are the same word and use only alphanumeric characters.  The underscore ( _ ) is also okay.

Also note: the pictures shown here do not necessarily include every property field mentioned in the instructions.

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