Easy Monster Spawner v3.0

🚀How To Use

Easy Monster Spawner works in two modes: TriggerBox mode (classic — spawn when player enters an area) or Standalone mode (place on any actor, trigger from Blueprint/C++). Here's how to set up both.

Option A — TriggerBox Mode (Classic)

Enable the Plugin

In Unreal Editor go to Edit → Plugins, find Easy Monster Spawner, enable it, and restart the editor.

Place a TriggerBox

From Place Actors → All Classes, drag a TriggerBox into your level. Scale it to cover the area where you want player entry to trigger spawns.

Add the Component

Select the TriggerBox, click +Add Component, search for "Monster Spawner" and add it.

Set Monster Class

In the Details panel under Classic Configuration, set Monster Class to your enemy Blueprint (e.g. BP_Zombie). Set Spawn Count, Spawn Pattern, and Spawn Radius.

Play!

Hit Play and walk into the TriggerBox. Monsters will spawn around it.

Tip: Enable Show Debug Visualization in the Debug category to see spawn locations as cyan spheres in the editor viewport.

Option B — Standalone Mode (NEW in v3.0)

Add to Any Actor

Add the Monster Spawner component to any actor in your level — an empty Actor, a Blueprint, a character, anything.

Set Activation Mode

In the Activation category, change Activation Mode to one of: Manual, Timer Auto-Spawn, or Begin Play.

Configure & Trigger

Set up your monster class and spawn settings as normal. For Manual mode, call TriggerSpawn() from your Blueprint or C++ code when ready.

If Activation Mode is set to TriggerBox but the owner actor is not a TriggerBox, the plugin automatically falls back to Manual mode and logs a warning.

Using the Wave System

Enable Waves

Check Use Wave System in the Wave System category.

Add Wave Entries

Click + on the Waves array to add wave configurations. Each wave has its own Monster Class, Spawn Count, Pattern, Effects, Formation, and Clear Requirements.

Optional: Wave Clear

In each wave's Clear Requirements, enable Require Wave Clearance. Set the kill percentage required before the next wave starts.

Optional: Loop

Enable Loop Waves and set Difficulty Scale Per Loop for infinite scaling encounters.

Blueprint Integration — Quick Example

// Trigger spawn from a gameplay event (e.g. button press)
Event AnyEvent
  → Get Component by Class (Monster Spawner v3.0)
    → TriggerSpawn()

// Check if all monsters are dead
Event Tick
  → Get Component by Class (Monster Spawner v3.0)
    → GetAliveMonsterCount()
      → Branch (Count == 0)
          → True: Open Door / Give Reward

✨Feature Overview

NEW v3.0

🔓 Standalone Mode

No TriggerBox needed. 4 activation modes: TriggerBox, Manual, Timer, BeginPlay.

NEW v3.0

🐉 Multi-Class Waves

Mix enemy types with weighted random selection per wave or classic mode.

NEW v3.0

♻️ Object Pooling

Reuse actors for performance. Pre-allocate, auto-expand, return to pool.

NEW v3.0

🌐 Multiplayer

Server-authoritative spawning with replicated state sync.

NEW v3.0

👁️ Spawn Conditions

Line of sight, "not looking" horror mode, min/max player distance.

NEW v3.0

🔊 MetaSound + Attenuation

USoundBase support (SoundCue, MetaSound, SoundWave) + 3D attenuation.

v2.5

💥 Spawn Effects

Niagara VFX + SFX for pre-spawn and post-spawn with configurable delay.

v2.5

⚔️ RTS Formations

8 formation types: Wedge, Line, Column, Square, Staggered, Phalanx, Circle, Scatter.

v2.5

💀 Wave Clear

Require kill percentage before next wave. Timeout with force-proceed option.

v2.5

🌀 New Patterns

Line, Arc, V-Shape, Spiral spawn patterns.

v2.0

🌊 Multi-Wave System

Sequential waves with per-wave config, delay, difficulty scaling, loop.

v1.0

🧠 Smart Spawn

Ground trace, NavMesh validation, overlap avoidance, ground alignment.

⚡Activation Modes

Set via the Activation Mode property in the Activation category.

Mode	How It Works	Owner Requirement
TriggerBox	Spawns when a player-controlled character overlaps the TriggerBox. Classic v1.0 behavior.	Must be ATriggerBox
Manual	Only spawns when you call `TriggerSpawn()` from Blueprint or C++.	Any actor
TimerBased	Automatically spawns on a repeating interval set by `AutoSpawnInterval` (seconds).	Any actor
BeginPlay	Spawns immediately when the game starts.	Any actor

Property	Type	Default	Description
ActivationMode	ESpawnActivationMode	TriggerBox	How this spawner is activated
AutoSpawnInterval	Float	30.0	Seconds between auto-spawns (TimerBased only, 0.1–300)

⚙️Classic Configuration

Used when Use Wave System is disabled. Single-trigger spawning.

Property	Type	Default	Description
MonsterClass	TSubclassOf<AActor>	None	Actor class to spawn (e.g. BP_Zombie)
ClassicMonsterClasses	TArray<FMonsterClassEntry>	[]	Multi-class list with weights. If populated, overrides MonsterClass. v3.0
SpawnCount	Int32	5	How many monsters to spawn (1–100)
SpawnPattern	ESpawnPattern	Circle	Spawn placement pattern
SpawnRadius	Float	500	Spawn area radius in cm (100–5000)
SpawnDelay	Float	0.2	Seconds between each monster spawn (0 = all at once)
DeactivationDelay	Float	0.0	Seconds before trigger deactivates after spawn starts
bFaceTriggerCenter	Bool	false	Rotate spawned monsters to face the trigger/owner center
AdditionalTagsForSpawnedMonsters	TArray<FName>	[]	Tags added to every spawned monster

General Settings (both modes)

Property	Type	Default	Description
bOneTimeOnly	Bool	true	Trigger works only once?
SpawnHeightOffset	Float	50	Z-offset above ground for spawn location (0–500 cm)

🌊Wave System

Property	Type	Default	Description
bUseWaveSystem	Bool	false	Enable multi-wave spawning
Waves	TArray<FWaveConfiguration>	[]	Array of wave configs
bLoopWaves	Bool	false	Restart from wave 0 after last wave completes
DifficultyScalePerLoop	Float	1.2	Multiplier for SpawnCount each loop (1.0–3.0)

FWaveConfiguration (per wave)

Property	Type	Description
MonsterClass	TSubclassOf<AActor>	Single monster class for this wave
MonsterClasses	TArray<FMonsterClassEntry>	Multi-class list (overrides MonsterClass if populated) v3.0
SpawnCount	Int32	How many to spawn (1–100)
SpawnPattern	ESpawnPattern	Spawn placement pattern
SpawnRadius	Float	Radius in cm (100–5000)
SpawnDelay	Float	Delay between each monster (0–10s)
DelayBeforeNextWave	Float	Seconds after this wave before next starts (0–60)
bFaceTriggerCenter	Bool	Rotate to face trigger/owner center
MonsterTags	TArray<FName>	Tags for this wave's monsters
bUseCustomEffects	Bool	Override global effects for this wave
CustomSpawnEffects	FSpawnEffectConfig	Per-wave effects (if above is true)
bUseFormation	Bool	Use formation spawning for this wave
FormationConfig	FFormationConfig	Per-wave formation settings
ClearRequirement	FWaveClearRequirement	Kill requirement before next wave

🐉Multi-Class Waves v3.0

Mix different enemy types in a single wave using weighted random selection.

FMonsterClassEntry

Property	Type	Default	Description
MonsterClass	TSubclassOf<AActor>	None	The monster class
SpawnWeight	Int32	1	Relative weight (higher = more likely, 1–100)
MonsterTags	TArray<FName>	[]	Tags unique to this monster type

Example Setup

// 70% Skeletons, 20% Trolls, 10% Boss
ClassicMonsterClasses:
  [0] MonsterClass: BP_Skeleton, SpawnWeight: 7
  [1] MonsterClass: BP_Troll,    SpawnWeight: 2
  [2] MonsterClass: BP_MiniBoss, SpawnWeight: 1

If MonsterClasses (wave) or ClassicMonsterClasses (classic) is populated, it overrides the single MonsterClass field. You can use both in the same project — single class for simple waves, multi-class for variety waves.

🎯Spawn Patterns

9 patterns available via the ESpawnPattern enum:

CircleGridRandom SpawnPointsLineArc VShapeSpiralFormation

🔵 Circle

Evenly spaced around center at SpawnRadius distance. Great for surrounding the player.

📐 Grid

NxN grid within SpawnRadius. Perfect for organized formations.

🎲 Random

Random positions within SpawnRadius. Unpredictable encounters.

📍 Spawn Points

Uses child SceneComponents of the owner as custom positions. Falls back to Circle if none found.

➖ Line

Straight line across SpawnRadius×2 length.

🌙 Arc

180° arc at SpawnRadius distance.

✌️ V-Shape

V/arrow formation with leader at front.

🌀 Spiral

Outward spiral with 2 full rotations.

⚔️ Formation

Uses the RTS Formation System (see below).

⚔️RTS Formation System

8 formation types via EFormationType:

WedgeLineColumnSquare StaggeredPhalanxCircleScatter

FFormationConfig

Property	Type	Default	Description
FormationType	EFormationType	Wedge	Which formation to use
UnitSpacing	Float	150	Distance between units (50–500 cm)
FormationFacingAngle	Float	0	Rotation offset from owner's forward (-180 to 180°)
bUnitsUseFacingDirection	Bool	true	Units face the formation direction
FormationDepth	Int32	3	Rows for multi-row formations (1–10)
WedgeAngle	Float	45	Wedge opening angle (15–90°)
RandomOffset	Float	0	Random jitter for organic look (0–100 cm)

💥Spawn Effects

Enable with bUseSpawnEffects. Configure globally or per-wave.

FSpawnEffectConfig

Property	Type	Description
PreSpawnVFX	TSoftObjectPtr<UNiagaraSystem>	Niagara effect before monster appears
PostSpawnVFX	TSoftObjectPtr<UNiagaraSystem>	Niagara effect after monster spawns
PreSpawnSFX	TSoftObjectPtr<USoundBase>	Sound before spawn (SoundCue, MetaSound, SoundWave) v3.0
PostSpawnSFX	TSoftObjectPtr<USoundBase>	Sound after spawn v3.0
SoundAttenuation	TSoftObjectPtr<USoundAttenuation>	3D audio falloff settings v3.0
PreSpawnDelay	Float	Seconds between pre-effect and actual spawn (0–5)
EffectScale	Float	VFX scale multiplier (0.1–10)
bAttachPostEffectToMonster	Bool	Attach post-spawn VFX to the actor

👁️Spawn Conditions v3.0

Control where and when monsters can spawn relative to the player.

FSpawnConditions

Property	Type	Default	Description
bRequireLineOfSight	Bool	false	Only spawn at locations visible to any player (not blocked by geometry)
bSpawnOnlyWhenPlayerNotLooking	Bool	false	Only spawn when no player is looking at the location (horror mode!)
PlayerLookAngleThreshold	Float	60	FOV half-angle to consider "looking at" (10–180°)
MinDistanceFromPlayer	Float	0	Minimum distance from any player (0 = no limit)
MaxDistanceFromPlayer	Float	0	Maximum distance from any player (0 = no limit)

Horror game tip: Set bSpawnOnlyWhenPlayerNotLooking = true + MinDistanceFromPlayer = 500 for enemies that appear behind you when you're not looking!

💀Wave Clear Requirements

FWaveClearRequirement

Property	Type	Default	Description
bRequireWaveClearance	Bool	false	Must kill monsters before next wave?
RequiredKillPercentage	Float	100	% of monsters that must die (0–100)
MaxWaitTime	Float	0	Timeout in seconds (0 = infinite)
bForceNextWaveOnTimeout	Bool	true	Force next wave when timeout expires

♻️Object Pooling v3.0

Reuse actor instances instead of Spawn/Destroy for better performance with large waves.

Property	Type	Default	Description
bUseObjectPooling	Bool	false	Enable pooling
InitialPoolSize	Int32	10	Pre-spawned hidden actors at BeginPlay (1–200)
MaxPoolSize	Int32	50	Maximum pool capacity (0 = unlimited)
bAutoExpandPool	Bool	true	Create new actors when pool is empty

How Pooling Works

At BeginPlay, the pool pre-spawns InitialPoolSize actors hidden at (0,0,-10000).
When spawning, the system first tries to reuse a pooled actor of the requested class.
If pool is empty and bAutoExpandPool is true, a new actor is spawned (up to MaxPoolSize).
If pool is exhausted and can't expand, falls back to standard SpawnActor.
Call ReturnToPool(Monster) instead of Destroy to recycle the actor.

Pool Blueprint Functions

Function	Description
ReturnToPool(AActor*)	Deactivate and return an actor to the pool
DestroyPool()	Destroy all pooled actors (available + in use)
GetPoolAvailableCount()	Number of ready-to-use actors in pool
GetPoolTotalSize()	Total pool size (available + in use)

🌐Multiplayer Replication v3.0

Property	Type	Default	Description
bEnableReplication	Bool	false	Enable server-authoritative spawning

When enabled:

Client calls to TriggerSpawn() are routed to the server via Server_TriggerSpawn RPC.
bHasTriggered, bSpawnInProgress, MonstersSpawned, and CurrentWaveIndex replicate to all clients.
Spawned actors follow standard UE replication (set your monster BP to replicate separately).

🧠Smart Spawn System

Property	Type	Default	Description
bUseGroundTrace	Bool	true	Line trace to find ground surface
GroundTraceDistance	Float	1000	Max downward trace distance (100–5000 cm)
bUseNavMesh	Bool	true	Validate spawn on NavMesh (AI can navigate)
NavMeshQueryExtent	Float	500	NavMesh search radius (100–1000 cm)
bAvoidOverlap	Bool	true	Prevent spawning on top of existing actors
MinSpawnDistance	Float	100	Minimum distance between spawned monsters (50–500 cm)
MaxSpawnAttempts	Int32	10	Retries per monster to find valid location (1–50)
bAlignToGround	Bool	false	Align rotation to ground normal (for slopes)

📘Blueprint Functions

Function	Type	Description
TriggerSpawn()	Callable	Start spawning (works in all modes)
HasBeenTriggered()	Pure	Returns true if spawner was already triggered
ResetSpawner()	Callable	Reset all state, re-enable trigger
GetAliveMonsterCount()	Pure	Number of alive monsters from this spawner
GetSpawnedMonsters()	Pure	Array of all alive spawned actors
GetSpawnCenter()	Pure	World location of spawn center (trigger or owner) v3.0
GetCurrentWaveIndex()	Pure	Current wave index (0-based, -1 if not started)
GetTotalWaves()	Pure	Number of configured waves
IsWaveInProgress()	Pure	True if currently spawning a wave
SkipToNextWave()	Callable	Stop current wave, proceed to next
GetCurrentWaveKillPercentage()	Pure	% of current wave monsters killed
IsCurrentWaveCleared()	Pure	True if kill requirement met
IsWaitingForWaveClear()	Pure	True if waiting for player to clear wave
ForceClearWave()	Callable	Force-proceed to next wave
ReturnToPool(AActor*)	Callable	Return monster to object pool v3.0
DestroyPool()	Callable	Destroy all pooled actors v3.0
GetPoolAvailableCount()	Pure	Available pool actors v3.0
GetPoolTotalSize()	Pure	Total pool size v3.0

📡Blueprint Events (Delegates)

Event	Parameters	Description
OnWaveStarted	int32 WaveIndex	Fired when a wave begins spawning
OnWaveCompleted	int32 WaveIndex, int32 MonstersSpawned	Fired when all monsters in a wave are spawned
OnAllWavesCompleted	—	Fired when the last wave finishes
OnWaveCleared	int32 WaveIndex, float ClearTime	Fired when kill requirement is met
OnMonsterSpawned	AActor* Monster, int32 SpawnIndex	Fired for each individual monster spawn
OnMonsterDied	AActor* DeadMonster	Fired when a spawned monster is destroyed
OnMonsterReturnedToPool	AActor* PooledMonster	Fired when a monster is returned to pool v3.0
OnSpawnFailed	int32 MonsterIndex, FVector Location	Fired when a spawn fails (no valid location) v3.0

🔍Debug & Visualization

Property	Type	Default	Description
bShowDebugVisualization	Bool	true	Draw spawn radius + preview points in editor
bShowSpawnValidation	Bool	false	Draw green/red spheres during runtime for valid/invalid spawn attempts

All log messages use the LogMonsterSpawner category. Filter in Output Log with: LogMonsterSpawner

🔧Troubleshooting

Monsters Don't Spawn

Check Monster Class is set (not None)
For TriggerBox mode: owner must be an ATriggerBox
For Standalone: check Activation Mode is not TriggerBox
Check Output Log → filter LogMonsterSpawner
If using multi-class: at least one entry must have a valid class

Monsters Spawn Underground or Floating

Adjust SpawnHeightOffset (default 50 cm)
Enable Use Ground Trace
Increase GroundTraceDistance if terrain is uneven

Pool Not Working

Ensure bUseObjectPooling is checked
Check log for "No class for pre-allocation" — set MonsterClass first
Call ReturnToPool() instead of Destroy() on your monsters

Multiplayer Issues

Enable bEnableReplication
Ensure your monster Blueprints also replicate (Actor → Replicates = true)
Spawning only happens on the server — state replicates automatically

Performance: Spawning 50+ monsters at once (SpawnDelay=0) can cause frame drops. Use a delay of 0.1–0.3s, or enable Object Pooling for large waves.

🎮 Easy Monster Spawner

🚀How To Use

Option A — TriggerBox Mode (Classic)

Enable the Plugin

Place a TriggerBox

Add the Component

Set Monster Class

Play!

Option B — Standalone Mode (NEW in v3.0)

Add to Any Actor

Set Activation Mode

Configure & Trigger

Using the Wave System

Enable Waves

Add Wave Entries

Optional: Wave Clear

Optional: Loop

Blueprint Integration — Quick Example

✨Feature Overview

🔓 Standalone Mode

🐉 Multi-Class Waves

♻️ Object Pooling

🌐 Multiplayer

👁️ Spawn Conditions

🔊 MetaSound + Attenuation

💥 Spawn Effects

⚔️ RTS Formations

💀 Wave Clear

🌀 New Patterns

🌊 Multi-Wave System

🧠 Smart Spawn

⚡Activation Modes

⚙️Classic Configuration

General Settings (both modes)

🌊Wave System

FWaveConfiguration (per wave)

🐉Multi-Class Waves v3.0

FMonsterClassEntry

Example Setup

🎯Spawn Patterns

🔵 Circle

📐 Grid

🎲 Random

📍 Spawn Points

➖ Line

🌙 Arc

✌️ V-Shape

🌀 Spiral

⚔️ Formation

⚔️RTS Formation System

FFormationConfig

💥Spawn Effects

FSpawnEffectConfig

👁️Spawn Conditions v3.0

FSpawnConditions

💀Wave Clear Requirements

FWaveClearRequirement

♻️Object Pooling v3.0

How Pooling Works

Pool Blueprint Functions

🌐Multiplayer Replication v3.0

🧠Smart Spawn System

📘Blueprint Functions

📡Blueprint Events (Delegates)

🔍Debug & Visualization

🔧Troubleshooting

Monsters Don't Spawn

Monsters Spawn Underground or Floating

Pool Not Working

Multiplayer Issues