Game Code Mastery

AI System Setup

4 min read

This guide provides step-by-step instructions for integrating the Combat AI Behavior System, part of the Advanced ARPG Combat framework, into an Unreal Engine 5 project. Users will learn how to set up the system, configure default enemy AI behaviors, and test functionality using demo assets. The guide focuses on enabling the system to function as it does in the demo content, ensuring developers and designers can quickly implement dynamic enemy AI for Action RPGs.

Prerequisites

  • Unreal Engine 5.3 or later.
  • Plugins enabled: Gameplay Tags, AI Framework (default in UE5).
  • Dependencies: State Manager System, Advanced Abilities System, Attributes System.
  • A level with a Nav Mesh Bounds Volume for AI navigation.
  • Optional: Enhanced Input System for testing player interactions with AI.

Integration Steps

  1. Migrate AI Folders:

    • In the Unreal Editor, open the demo project containing the Combat AI Behavior System.
    • In the Content Browser, locate the relevant AI folders:
      • Content/AdvancedARPGCombat/AdvancedCombatFramework/CoreCombatSystem/AI
      • Content/AdvancedARPGCombat/MeleeCombatSystem/Blueprints/AI (optional for melee AI)
      • Content/AdvancedARPGCombat/MagicCombatSystem/Blueprints/AI (optional for magic AI)
      • Content/AdvancedARPGCombat/RangedCombatSystem/Blueprints/AI (optional for ranged AI)
    • Right-click and select Migrate, then choose your project’s Content directory.
    • Ensure dependencies (e.g., State Manager System, Blueprints, Data Assets) are copied.

  2. Add BP_BaseEnemy to Level:

    • In your project’s Content Browser, locate BP_BaseEnemy in the migrated AI folder.
    • Drag BP_BaseEnemy into a level or use BP_EnemySpawner for dynamic spawning.
    • If using BP_EnemySpawner, set its Enemy Info property to a demo BP_EnemyInfo (e.g., BP_EnemyInfo_Humanoid) in the Details panel.

  3. Configure BP_BaseEnemy:

    • Select the placed BP_BaseEnemy or a spawned instance.
    • In the Details panel, ensure AI Controller Class is set to BP_BaseAIController.
    • Set EnemyInfo to a demo BP_EnemyInfo (e.g., BP_EnemyInfo_Humanoid) to initialize default behaviors, abilities, and attributes.
    • Verify BP_BehaviorManagerComponent and BP_PatrolComponent are present in the Components panel.

  4. Set Up Patrol Path (Optional):

    • Place a BP_PatrolPath actor in the level from the migrated AI folder.
    • In the Details panel, adjust Patrol Points using the 3D widget to define the patrol route.
    • Select the BP_BaseEnemyand, in its BP_PatrolComponent, set Patrol Path to the placed BP_PatrolPath.
    • If using the BP_EnemySpawner, select the BP_EnemySpawner and, in its details panel, set Patrol Path to the placed BP_PatrolPath.
    • Configure bLoopPatrolPath or bReverseDirection as needed.

  5. Configure Behavior Tree and State Machine:

    • Open the demo BP_EnemyInfo (e.g., BP_EnemyInfo_Humanoid) and verify:
      • Behavior Tree is set to a demo Behavior Tree (e.g., BT_HumanoidCombat).
      • Behavior Classes includes SM_Humanoid_CombatBehavior for default humanoid behaviors.
    • Ensure BP_BehaviorManagerComponent on BP_BaseEnemy references SM_Humanoid_CombatBehavior via BP_EnemyInfo.

  6. Add Navigation Mesh:

    • In the level, place a Nav Mesh Bounds Volume covering the AI’s operational area.
    • Press P to visualize the green navigation mesh, ensuring it encompasses patrol and combat areas.

  7. Test with Default Assets:

    • Play the level and observe the BP_BaseEnemy behavior:

      • Verify patrol behavior (if BP_PatrolPath is set) using BP_PatrolComponent.
      • Test combat by approaching with a player character; the AI should engage using abilities from BP_EnemyInfo.

    • Monitor health bar visibility:

      OnDamageApplied -> ShowHealthBar

    • Test ragdoll on death:

      OnDamageApplied -> Is Health Zero? -> Branch (True) -> EnableRagdoll

    • Debug Behavior Tree tasks:

      BP_BaseAIController -> UpdateTarget -> Set Blackboard Value As Object (Key: TargetActor, Value: Player)

Troubleshooting

  • AI Not Moving:
    • Ensure a Nav Mesh Bounds Volume is present and covers the AI’s area.
    • Verify BP_PatrolPath is assigned to BP_PatrolComponent if patrolling.
    • Check BP_BaseAIController is set as the AI Controller Class in BP_BaseEnemy.
  • AI Not Engaging in Combat:
    • Confirm HostileTags in BP_EnemyInfo or BP_BehaviorManagerComponent include player tags (e.g., Player.Character).
    • Ensure Behavior Tree and SM_Humanoid_CombatBehavior are set in BP_EnemyInfo.
    • Verify UpdatePerception is detecting the player via BP_BaseAIController.
  • Abilities Not Triggering:
    • Check Default Ability Sets in BP_EnemyInfo includes valid abilities (e.g., GA_EnemyMeleeAttack).
    • Ensure Combat Style in BP_EnemyInfo is set and matches the AI’s abilities.
  • Health Bar Not Showing:
    • Verify ShowHealthBar is called in OnDamageApplied in BP_BaseEnemy.
    • Ensure the health bar widget is set in InitializeHUD or BP_EnemyInfo.

Notes

  • Migration: Always migrate entire AI folders to ensure dependencies (e.g., abilities, animations) are included.
  • Enemy Info: Use BP_EnemyInfo for all AI configurations to leverage async loading and avoid hard references.
  • Navigation: AI behaviors like patrolling or chasing require a valid navigation mesh; adjust Nav Mesh Bounds Volume size for larger levels.
  • Testing: Test with demo BP_EnemyInfo assets before customizing to understand default behavior.
  • Dependencies: Ensure State Manager, Advanced Abilities, and Attributes systems are migrated and functional, as they are critical for AI behavior and abilities.

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