Step-by-Step Enemy Creation

Comprehensive guide to creating a complete enemy from scratch with weapons, animations, and advanced features.

This section provides comprehensive instructions for creating a complete enemy from scratch, including weapons, animations, and advanced features.

Prerequisites

Before starting, ensure you have:

• Character skeletal mesh with animations
• Attack animation montages with hit frames identified
• Basic understanding of Gameplay Ability System
• Unreal Engine 5.7 installed

Step 1: Character Setup

Create Blueprint: BP_DetailedEnemy (inherits AEnemyCharacterBase)

In Components Panel:

1. Select SkeletalMesh component

   • Set your character mesh
   • Configure materials

2. Select CapsuleComponent

   • Adjust radius to fit mesh
   • Set height appropriately

3. Select CharacterMovement component

   • Max Walk Speed: 400
   • Max Acceleration: 2048
   • Rotation Rate: (Pitch=0, Yaw=360, Roll=0)

What You Get Automatically:

• USECMeleeTraceComponent - Already added by base class
• UAbilitySystemComponent - Already configured
• IAbilitySystemInterface - Already implemented

Step 2: AI Controller Setup

Create Blueprint: BP_DetailedEnemyController (inherits AEnemyControllerBase)

What the base class provides:

// These components are automatically added:
UMovementEvaluatorComponent*    // Tactical movement
UThreatDetectionComponent*      // Player attention tracking
UActionEvaluationComponent*     // Action scoring & execution
UBehaviorTreeComponent*         // For BT sequence execution

Configure Movement:

Open BP_DetailedEnemyController → Details Panel → Movement Evaluator:

Distance Settings:
  IdealMinDistance: 150.0
  IdealMaxDistance: 300.0
  
Strafe Settings:
  StrafeRadius: 200.0
  StrafeDuration: 3.0
  StrafeCooldown: 2.0
  
Navigation:
  DirectControlThreshold: 600.0
  AvoidanceRadius: 100.0
  
Debug:
  bDebugLog: false (enable to see movement decisions)

Configure Action Evaluation:

Details Panel → Action Evaluation:

CurrentActionSet: DA_DetailedEnemyActions (create next)
NoveltyDecayRate: 0.2
bDebugLog: true (enable to see action scoring)

Step 3: Create Comprehensive ActionSet

Create Data Asset: DA_DetailedEnemyActions (type: ActionSet)

Add Multiple Actions for Variety:

Action 1: Light Attack (Close Range)

Action 2: Heavy Attack (Medium Range)

Action 3: Defensive Retreat (When Too Close)

Step 4: Create Gameplay Abilities

For each action using GameplayAbility execution mode, create an ability Blueprint.

Example: GA_LightAttack

Class Defaults:

• Ability Tags: SEC.Action.LightAttack
• Activation Policy: OnSpawn

Event Graph Implementation:

Event ActivateAbility
  ↓
[Branch: Check if montage valid]
  ↓ True
Play Montage and Wait
  • Montage: AM_LightAttack
  • Rate: 1.0
  ↓ On Completed
Send Gameplay Event to Actor
  • Target: Get Avatar Actor from Actor Info
  • Event Tag: SEC.Action.End
  • Payload: (optional ActionInfo)
  ↓
End Ability
  • Cancel: false
  
  ↓ On Cancelled/Interrupted
Send Gameplay Event to Actor (SEC.Action.End)
  ↓
End Ability

Important: Always send the SEC.Action.End event, even if interrupted. Otherwise, the AI gets stuck.

Step 5: Configure Animation Montages

Create Montage: AM_LightAttack from your attack animation

Add Melee Trace Notify State:

1. Right-click timeline at attack's active frames
2. Add Notify State → SECMeleeTraceNotifyState
3. Duration: Cover the weapon swing (e.g., frames 10-25)

Configure Notify State:

Details Panel:

Socket IDs: ["Blade"]  // Must match weapon trace socket

Add End Event Notify:

1. Near montage end (e.g., frame 40)
2. Add Notify → AnimNotify_GameplayCue
3. Gameplay Cue Tag: SEC.Action.End

Timing Example:

Frame:     0    10    20    30    40    50
Animation: [━━━━][━━━━][━━━━][━━━━][━━━━]
           Windup Strike  Follow Recovery
Trace:          [═════════]
End Event:                          ▲

Step 6: Create Weapon

Create Blueprint: BP_Sword (inherits ASECWeaponBase)

Class Defaults:

Attachment:

AttachSocket: "RightHandSocket"  // Socket on character skeleton

Trace Sockets Array:

Add element [0]:

ID: "Blade"
Shape: CapsuleTwoPoint
SocketOrBoneName: "blade_start"    // Socket on weapon mesh
EndSocketOrBoneName: "blade_end"   // Socket on weapon mesh
Radius: 15.0
TraceChannel: ECC_GameTraceChannel1

Damage Configuration:

DamageConfig: DA_SwordDamage  // Create data asset

Weapon Mesh Setup:

1. Components → WeaponMesh → Set your sword static/skeletal mesh
2. Add sockets to weapon mesh:
   • blade_start at blade base
   • blade_end at blade tip
3. Position sockets along the cutting edge

What Happens Automatically:

• On equip → Registers trace sockets with character's MeleeTraceComponent
• During montage notify → Traces activate between sockets
• On hit → Applies damage via DamageConfig

Step 7: Create Damage Configuration

Create Data Asset: DA_SwordDamage (type: SECDamageConfig)

BaseDamage: 25.0
DamageType: UDamageType (or custom class)
ImpulseStrength: 500.0
bCanCritical: false

Step 8: Build StateTree Logic

Create StateTree: ST_DetailedEnemy

Root State Configuration:

StateTree: ST_DetailedEnemy

├─ Root State (Always Active)
│  │
│  ├─ [Tick] STTask_BuildDecisionContext
│  │  • TargetActor: Get Player Character (or blackboard)
│  │  • Output Pin: DecisionContext (FDecisionContext struct)
│  │
│  ├─ [Tick] STTask_AIMovement
│  │  • Context: DecisionContext (linked from above)
│  │  • MovementProfile: (empty = use controller defaults)
│  │
│  └─ Transition → Combat State
│     • Condition: DecisionContext.TargetActor Is Valid
│
└─ Combat State
   │
   ├─ Decision Substate
   │  │
   │  ├─ [Enter] STTask_PollAction
   │  │  • Context: DecisionContext
   │  │  • Output: ChosenAction (FChosenAction struct)
   │  │
   │  └─ Transition → Execute State
   │     • Condition: ChosenAction.IsValid == true
   │
   └─ Execute Substate
      │
      ├─ [Enter] STTask_DoAction
      │  • ChosenAction: (from PollAction)
      │  • TargetActor: DecisionContext.TargetActor
      │  • WaitForCompletion: true
      │
      └─ Transition → Decision State
         • Condition: DoAction.Completed == true

Step 9: Test Your Enemy

Place in Level:

1. Drag BP_DetailedEnemy into level
2. Details Panel → Pawn → AI Controller Class → BP_DetailedEnemyController

Debug Configuration:

Enable logging in controller:

ActionEvaluation → bDebugLog: true
MovementEvaluator → bDebugLog: true

Play and Observe:

Output Log Messages:

LogEvaluation: Evaluating 3 actions for BP_DetailedEnemy_1...
LogEvaluation: [LightAttack] Dist:180 Angle:15 Score:0.95 SELECTED
LogEvaluation: [HeavyAttack] Dist:180 Angle:15 Score:0.60 (cooldown)
LogEvaluation: [QuickRetreat] Dist:180 Angle:15 Score:0.10 (too far)

Expected Behavior:

• Approaches to ideal distance range
• Strafes around player
• Executes light attack when in optimal range
• Occasionally uses heavy attack
• Retreats if player gets too close

Common Issues