Ai Patrol System

AI Patrol System

Patrol Marker Setup

Patrol Marker Actor

Create visual waypoint system for AI patrol routes:

Actor Components

• Sphere Component: Root component for positioning
• Dynamic Material: Translucent blue material for designer visibility
• Text Render Component: Display route information
• Collision Settings: No collision, hidden in game

Visual Configuration

• Material: Light blue, 80% opacity for clear visibility
• Color Variable: Instance-editable for different route identification
• Text Display: Route order and naming information

Patrol Route Organization

Tag-Based System

Use Unreal Engine tags for route organization:

• Route Identifier: Letter tags (A, B, C) for different patrol routes
• Order Numbers: Number tags (1, 2, 3) for waypoint sequence
• Text Display: Shows both route letter and sequence number

Tag Implementation

// Patrol Marker Display System
OnConstruct() {
route_name = Tags[1]; // Letter (A, B, C)
route_point = Tags[0]; // Number (1, 2, 3)

display_text = route_name + ' ' + route_point;
TextRender.SetText(display_text);
}

Level Design Integration

• Visual Clarity: Bright yellow text for high visibility
• Route Planning: Clear progression from point 1→2→3→2→1
• Multiple Routes: Different colored spheres for different patrol paths

AI Patrol Implementation

Patrol Route Setup

Configure AI characters for patrol behavior:

Spawner Integration

• Patrol Route Variable: Name-type variable on AI spawner
• Route Assignment: Spawner passes patrol route to spawned AI
• Interface Communication: Interface_Set_AI_Patrol_Route function

Route Discovery Process

// AI Route Discovery
OnPatrolRouteAssignment(PatrolRouteName) {
if (PatrolRouteName != 'None') {
patrol_markers = GetAllActorsOfClassWithTag(Actor_Patrol_Marker, PatrolRouteName);
SortMarkersByTag(patrol_markers); // Sort by number tags
patrol_route_array = sorted_markers;

DelayedStart(RandomFloat(1.0, 3.0)); // Stagger patrol starts
CE_Patrol_Route();
}
}

Route Sorting Algorithm

Sort patrol markers by number tags for proper sequence:

// Marker Sorting Implementation
SortMarkersByTag(UnsortedMarkers) {
ForEach(marker in UnsortedMarkers) {
tag_number = ConvertStringToInt(marker.Tags[0]);
sorted_array[tag_number] = marker;
}
return sorted_array;
}

Patrol Movement Logic

Bidirectional Patrol System

Implement back-and-forth patrol movement:

Patrol State Variables

• Patrol_Index Integer: Current patrol point (starts at 1, ignores index 0)
• Patrol_Reverse Boolean: Direction of patrol movement
• Patrol_Destination Vector: Current target location

Patrol Direction Logic

// Bidirectional Patrol Movement
OnReachDestination() {
if (!Patrol_Reverse) {
Patrol_Index++;
if (Patrol_Index > LastArrayIndex) {
Patrol_Reverse = true;
Patrol_Index = LastArrayIndex - 1;
}
} else {
Patrol_Index--;
if (Patrol_Index < 1) {
Patrol_Reverse = false;
Patrol_Index = 1;
}
}

DelayedPatrolContinue(RandomFloat(1.0, 3.0));
}

Movement Integration

Connect patrol system to AI movement:

• Move Speed: Set to walk during patrol
• AI_Move_To: Use location mode with patrol destinations
• Distance Check: Monitor arrival at patrol points (150-unit tolerance)

Patrol Interruption System

Aggro Integration

Handle player detection during patrol:

Detection Response

• Stop Patrol: Clear patrol timers when player detected
• Combat Priority: Aggro behavior overrides patrol behavior
• Resume Delay: 10-second timer before resuming patrol after losing player

// Patrol Interruption Management
OnPlayerAggro() {
ClearAndInvalidateTimer(Timer_Patrol_Route);
ClearAndInvalidateTimer(Timer_Check_Patrol_Destination);

// Set timer to resume patrol if player escapes
Timer_Reset_Patrol = CreateTimer(10.0, false);
}

State Management

• Combat State: Patrol disabled during combat
• Death State: Stop all movement when AI dies
• Reset State: Return to patrol after leash reset

Patrol Polish Features

Variable Patrol Timing

Add natural variance to patrol behavior:

• Random Delays: 1-3 second random pauses at waypoints
• Staggered Starts: 1-3 second random delay before initial patrol
• Human-Like Behavior: Prevents robotic, synchronized movement

Integration with Other Systems

• Player Noise: Detection interrupts patrol
• Combat: Patrol resumes after combat ends
• Death/Respawn: Patrol restarts with respawned AI
• Leash System: Patrol continues from current progress after reset

The AI patrol system creates dynamic, believable enemy behavior that enhances level design possibilities while integrating seamlessly with combat and detection systems.