Ai Behavior System

AI Behavior System

AI Aggro Implementation

Detection Range Setup

Create AI aggro system for enemy detection and engagement:

Aggro Collision Sphere

• Component: Sphere collision named “CollisionSphere_Aggro”
• Position: At AI character feet (Z location -90)
• Radius: 800 units for detection range
• Collision Settings: Custom collision, ignore all, overlap pawn only

Player Detection System

Implement player-specific detection to prevent AI attacking each other:

Character Type Interface

Create interface function to identify character types:

• Interface_Character_Type: Returns boolean for player identification
• Player Character: Returns true
• AI Characters: Returns false (default)
• NPC Characters: Returns false

Aggro Trigger Logic

// AI Aggro Detection
OnAggroSphereOverlap(OtherActor) {
if (OtherActor.Interface_Character_Type()) {
// This is the player character
F_Aggro_Player(OtherActor);
CE_SpawnLocation_Leash(); // Start leash timer
}
}

AI Leash System

Spawn Location Management

Prevent AI from wandering too far from spawn point:

Leash Variables

• Spawn_Location Vector: Store original spawn position on begin play
• Leash_Distance Float: Maximum distance from spawn (default 1000 units)
• Timer_Check_Leash_Distance: Periodic distance checking

Leash Implementation

// AI Leash System
CE_SpawnLocation_Leash() {
Timer_Check_Leash_Distance = CreateTimer(1.0, true); // Check every second
}

CE_CheckLeashDistance() {
current_distance = Distance(GetActorLocation(), Spawn_Location);

if (current_distance > Leash_Distance) {
CE_Reset_AI_Character();
}
}

AI Reset Process

Return AI to spawn location when leash exceeded:

// AI Character Reset
CE_Reset_AI_Character() {
StopMovementImmediately();
DisableAggroCollision();

AI_Move_To(Spawn_Location, false); // Move to location, not actor

// Wait for arrival before re-enabling
Timer_CheckForSpawnLocation(1.0, true);
}

AI Movement System

Consolidated Move Function

Create single function for all AI movement needs:

F_AI_Move_To Function

• Vector Input: Target location
• Actor Input: Target actor to follow
• Use_Actor Boolean: Choose between location and actor movement
• Conditional Logic: Prevent movement during reset or death states

Movement Validation

// AI Movement with Conditions
F_AI_Move_To(Location, Actor, Use_Actor) {
if (!Dead && !Reset) {
if (Use_Actor) {
MoveToActor(Actor, AcceptanceRadius);
} else {
MoveToLocation(Location, AcceptanceRadius);
}
}
}

Player Detection Phases

Three-Phase Detection System

Implement escalating AI response to player presence:

Detection Value System

• Player_Detection Integer: Accumulates detection level
• Phase Thresholds: 33, 66, 100 for different behaviors
• Value Sources: Player noise, visual contact, damage taken

Detection Phases

// AI Detection Phases
OnDetectionUpdate(Value) {
Player_Detection += Value;

if (Player_Detection < 33) {
// Phase 0: No response
return;
} else if (Player_Detection < 66) {
// Phase 1: Look at player direction
LookAtPlayer(Player_Detected);
} else if (Player_Detection < 100) {
// Phase 2: Walk to player location
SetMoveSpeed(Walk);
AI_Move_To(Player_Detected.Location, true);
} else {
// Phase 3: Attack player
SetMoveSpeed(Run);
F_Aggro_Player(Player_Detected);
}
}

Combat Integration

Aggro on Damage

Immediate aggro when AI receives damage:

Damage Response System

• Last_Attacker Variable: Track who damaged this AI
• Player Check: Verify attacker is player character
• Immediate Aggro: Skip detection phases and go straight to combat

// AI Damage Response
F_On_Damage_Received() {
if (Last_Attacker.Interface_Character_Type()) {
// Immediate aggro on player damage
F_Aggro_Player(Last_Attacker);
}
}

State Reset Integration

• Death Reset: Clear detection values when AI dies
• Leash Reset: Reset detection when returning to spawn
• Combat End: Gradually reduce detection over time

The AI behavior system creates engaging, predictable enemy encounters with proper state management and realistic response patterns that enhance gameplay without creating frustrating or confusing AI behavior.