Add an NPC to a Conversation

Prerequisites

• Create a persona

Now that you have created your first persona and refined its personality through interacting with it in the Prompt Editor, you can add your NPC to a conversation. To converse with an NPC in game, you must:

• Define a new npc_behavior in Verse.

• Add your npc_behavior to your NPC Character Definition.

• Add your NPC Character Definition to an NPC Spawner.

• Ensure you have Voice Chat Enabled as Voice Chat is required to converse with persona NPCs.

Create an Empty NPC Behavior

To set up a custom NPC Behavior in Verse, follow these steps:

1. In the Menu Bar, select Verse > Verse Explorer.

2. In the Verse Explorer, right-click on your project name and choose Add new Verse file to project to open the Create Verse Script window.

3. In the Create Verse Script window, click NPC Behavior Basic to select it as your template.

4. Name the NPC Behavior persona_npc_behavior under Configure.

5. Select Create to create your Verse file.

The persona_npc_behavior is where you can define and add a persona_component to your NPC through Verse. All NPCs spawned by NPC Spawners are agents and have an associated entity. This associated entity is how you add Scene Graph Components, such as the persona_component to an NPC agent.

NPC Behaviors are defined in Verse inheriting from the base npc_behavior class. For more information about NPC Behaviors, see the Understanding NPC Behaviors page.

Edit your Persona NPC Behavior

Verse is required to add your NPC persona as a conversation target for the player. Without adding your NPC as a conversation target for your player, you cannot converse with your NPC persona.

In the following sections, the Verse script defines the persona_npc_behavior . To add this Verse code to your empty persona_npc_behavior, follow these steps:

• In the Menu Bar, select Verse > Open Project in VS Code…

• Once VS Code opens, find your persona_npc_behavior.verse file in the VS Code Explorer.

• Copy and paste the content of persona_npc_behavior.verse below into your Verse file in your project.

• Compile your Verse code either in the UEFN Toolbar or within VS Code.

You can also use Verse to create experiences where a team of players interact with LLM agents. Verse handles the interactions between multiple players and the LLM agents using CreateAudioTeamAndAddPlayers(), AddMember(), and AddChatChannel().  

For a step-by-step walkthrough of the Verse script, follow the steps under Explanation of Script.

persona_npc_behavior.verse

using { /Fortnite.com/AI }
using { /Fortnite.com/Devices }
using { /Fortnite.com/Playspaces }

using { /UnrealEngine.com/Conversations }
using { /UnrealEngine.com/Temporary/Diagnostics }

using { /Verse.org/Chat }
using { /Verse.org/SceneGraph }
using { /Verse.org/Simulation }

Explanation of Script

1. The TeamName is the name for the voice channel being created.The OptionAgentGroup holds the group of agents going into the voice channel (TeamName). The OptionVoiceChannel is the variable of the actual Voice Channel that the players and NPC are in.   

   Verse

       #Team name for the Team Voice Channel we are creating.
       TeamName<localizes>:message = "Persona Chat"
   
   
       #Variable that stores the agent group we are using to create the voice channel. We can use this group to create new channels or get current players in a conversation.
       var OptionAgentGroup:?agent_group(team_member_info) = false
   
   
       #Variable that stores the Voice Channel that our players and NPC will be inside of. This is what actually holds the conversation.
       var OptionVoiceChannel:?voice_channel(team_member_info) = false

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2. AddPlayersAsConversationTarget sets up a live voice conversation between the NPC and every player in its playspace. The function first gathers everything it needs, and only if all of those succeed does it build the agent group and voice channel, wire the players and NPC into them, and register the players as conversation targets.  

   First it creates a new agent_group typed with team_member_info, which holds everyone in the conversation. It then creates a voice_channel (also typed with team_member_info), naming it with TeamName and pointing its Group at the agent group just created. This channel is what carries the conversation audio.

   Next it populates the group: it loops over every player in the playspace and adds each as a member, then adds the NPC agent as well, so all participants share one group.

   It then calls SimEntity.AddChatChannel(TeamVoiceChannel) to register the voice channel with the Audio Chat system, which brings the channel online. Finally it loops over the players again, calling SetConversationTarget on each so they're pointed at the NPC's persona_component through that channel.

   The last step stores the group and channel in the OptionAgentGroup and OptionVoiceChannel variables (wrapped in option{}), so later helper functions can reference or modify the conversation without rebuilding it.

   Verse

   
      # Add the Player as a conversation target for this NPC
       AddPlayersAsConversationTarget():void=
           if:
               NPCEntity := GetEntity[]
               Playspace := NPCEntity.GetPlayspaceForEntity[]
               NPCAgent := GetAgent[]
               Players := NPCEntity.GetPlayspaceForEntity[].GetPlayers()
               SimEntity := Players[0].GetSimulationEntity[]
               PersonaComponent := NPCEntity.GetComponent[persona_component]
   
   Expand code Copy full snippet(34 lines long)

3. RemovePlayerAsConversationTarget removes a single player from the NPC's conversation. It takes one player argument and calls ClearConversationTarget(), which detaches that player from whatever conversation target they were pointed at (The inverse of the SetConversationTarget call made in AddPlayersAsConversationTarget).  

   Verse

       # Remove Player as a conversation target
       RemovePlayerAsConversationTarget(Player:player):void=
           Player.ClearConversationTarget()
           Logger.Print("Removed from NPC conversation", ?Level := log_level.Debug)

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4. OnBegin adds the structured output to the session and sets the player as the conversation target. In a game where players can join late, you want to ensure you add them on the PlayerAddedEvent or when a player walks up to an NPC via a trigger.    

   Verse

       OnBegin<override>()<suspends>:void=
           AddPlayersAsConversationTarget()

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5. In OnEnd the Conversation is cleaned and removed from all players. This is good practice.  

   Verse

       OnEnd<override>():void=
           for (Player : GetEntity[].GetPlayspaceForEntity[].GetPlayers()):
               RemovePlayerAsConversationTarget(Player)

   Copy full snippet(3 lines long)

Add NPC Behavior to NPC Character Definition

To add your persona_npc_behavior to your NPC Character Definition, follow these steps:

1. Navigate to your PersonaNPCDefinition in the Content Drawer.

   

2. Select the PersonaNPCDefinition to open for editing.

3. Under NPC Character Behavior, select Verse Behavior > persona_npc_behavior.

   

4. Ensure you save your changes to your NPC Character Definition before closing the tab.

Once your NPC Character Definition is added to an NPC Spawner, your NPC persona is automatically added as a conversation target for your player.

Add NPC Spawner with NPC Character Definition

To spawn an NPC with your customized persona, you must add an NPC Spawner to your level and add your PersonaNPCDefinition. To add an NPC Spawner Device, drag your PersonaNPCDefinition from the Content Drawer into the Viewport.

Converse with your NPC

To converse with your NPC, launch a session and start the game. Press the key or button on your input device indicated on-screen and converse with your NPC!

Next Up

• 

  Drive Gameplay with Structured Output

  Explore how to use Verse to refine NPC conversations and behaviors.