Ai Spawner System

AI Spawner System

AI Spawner Architecture

Spawner Actor Components

Create a robust AI spawning system that handles enemy placement and respawning:

Core Components

• Sphere Visualization: Shows spawner location for level designers (hidden in game)
• Static Variables: Actor class, spawn delay, position validation

Spawner Configuration

• Actor Variable: Selectable AI character class to spawn
• Spawn Delay: 3-second default delay before spawning
• Instance Editable: Allow per-spawner customization in level editor

Spawn Location Validation

Line Trace for Ground Detection

Ensure AI spawns on valid ground surfaces:

// Safe Spawn Location Detection
OnSpawnerActivation() {
start_location = GetActorLocation() + Vector(0, 0, 500);
end_location = GetActorLocation() - Vector(0, 0, 500);

LineTraceForObjects(start_location, end_location, [WorldStatic, WorldDynamic]);

spawn_location = hit_location + Vector(0, 0, 100); // Slight elevation
SpawnActor(Actor_Class, spawn_location, GetActorRotation());
}

This system prevents AI from spawning inside geometry or falling through the world.

AI Controller Setup

Custom AI Controller

Create dedicated AI controller for enhanced AI behavior:

AI Controller Configuration

• Blueprint: AIController_Coursera
• Auto Possess: Set to “Placed in World or Spawned”
• Integration: Apply to all AI characters in class defaults

Spawner Interface System

Respawn Communication

Create interface for spawner-AI communication:

Interface_Spawner_AI

• Function: Respawn
• Purpose: AI characters call this when they die
• Implementation: Restart spawn delay timer

AI Death Integration

Connect AI death to respawn system:

// AI Death Respawn Chain
AI_Character.F_Dead() {
spawner = GetOwner(); // Set during spawn
spawner.Interface_Respawn();

// Delay destruction to allow respawn setup
TimerEvent(5_seconds) {
DestroyActor(Self);
}
}

Spawn Process Management

Owner Relationship

Establish proper ownership between spawner and AI:

Owner Assignment

• Spawn Actor: Set spawner as owner of spawned AI
• Override Controller: AI controller automatically becomes owner, must override
• Interface Function: Interface_Set_AI_Owner for proper owner assignment

Spawn Delay System

Implement configurable spawn timing:

Delay Implementation

• Event Begin Play: Trigger initial spawn after delay
• Respawn Delay: Same delay applies to respawn after AI death
• Variable Delay: Instance-editable spawn timing per spawner

AI Navigation Setup

Nav Mesh Integration

Ensure AI can navigate level properly:

Nav Mesh Bounds Volume

• Placement: Cover entire playable area
• Visualization: Press ‘P’ to see navigation mesh
• AI Movement: AI can only move within nav mesh bounds
• Level Design: Ensure nav mesh covers intended AI patrol areas

Spawner Placement Strategy

Level Design Integration

Position spawners strategically throughout levels:

Placement Considerations

• Enemy Distribution: Spread spawners for varied encounters
• Difficulty Scaling: Place stronger enemies in challenging locations
• Respawn Logic: Consider player progression when enemy respawns
• Navigation Access: Ensure spawned AI can reach intended areas

Multiple Enemy Types

• Varied Spawners: Different spawners for different AI types
• Class Selection: Choose appropriate AI character class per spawner
• Spawn Timing: Vary spawn delays to prevent synchronized enemy waves

Testing and Debugging

Spawn Validation

Test spawner system thoroughly:

• Ground Detection: Verify AI spawns on solid ground
• Navigation: Confirm AI can move after spawning
• Respawn Cycle: Test death-respawn cycle works correctly
• Owner Relationships: Ensure proper spawner-AI connections

Performance Considerations

• Spawn Limits: Monitor total AI count in level
• Cleanup: Ensure dead AI properly destroys
• Memory Management: Prevent accumulation of unused AI references

The AI spawner system provides flexible, level-designer-friendly enemy placement with robust respawn mechanics that support dynamic gameplay while maintaining performance and reliability.