Version: 2022.3
  • C#

ObjectPool<T0> Constructor

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public ObjectPool<T0>(Func<T> createFunc, Action<T> actionOnGet, Action<T> actionOnRelease, Action<T> actionOnDestroy, bool collectionCheck, int defaultCapacity, int maxSize);


createFunc Used to create a new instance when the pool is empty. In most cases this will just be () => new T().
actionOnGet Called when the instance is taken from the pool.
actionOnRelease Called when the instance is returned to the pool. This can be used to clean up or disable the instance.
actionOnDestroy Called when the element could not be returned to the pool due to the pool reaching the maximum size.
collectionCheck Collection checks are performed when an instance is returned back to the pool. An exception will be thrown if the instance is already in the pool. Collection checks are only performed in the Editor.
defaultCapacity The default capacity the stack will be created with.
maxSize The maximum size of the pool. When the pool reaches the max size then any further instances returned to the pool will be ignored and can be garbage collected. This can be used to prevent the pool growing to a very large size.


Creates a new ObjectPool instance.

using System.Text;
using UnityEngine;
using UnityEngine.Pool;

// This component returns the particle system to the pool when the OnParticleSystemStopped event is received. [RequireComponent(typeof(ParticleSystem))] public class ReturnToPool : MonoBehaviour { public ParticleSystem system; public IObjectPool<ParticleSystem> pool;

void Start() { system = GetComponent<ParticleSystem>(); var main = system.main; main.stopAction = ParticleSystemStopAction.Callback; }

void OnParticleSystemStopped() { // Return to the pool pool.Release(system); } }

// This example spans a random number of ParticleSystems using a pool so that old systems can be reused. public class PoolExample : MonoBehaviour { public enum PoolType { Stack, LinkedList }

public PoolType poolType;

// Collection checks will throw errors if we try to release an item that is already in the pool. public bool collectionChecks = true; public int maxPoolSize = 10;

IObjectPool<ParticleSystem> m_Pool;

public IObjectPool<ParticleSystem> Pool { get { if (m_Pool == null) { if (poolType == PoolType.Stack) m_Pool = new ObjectPool<ParticleSystem>(CreatePooledItem, OnTakeFromPool, OnReturnedToPool, OnDestroyPoolObject, collectionChecks, 10, maxPoolSize); else m_Pool = new LinkedPool<ParticleSystem>(CreatePooledItem, OnTakeFromPool, OnReturnedToPool, OnDestroyPoolObject, collectionChecks, maxPoolSize); } return m_Pool; } }

ParticleSystem CreatePooledItem() { var go = new GameObject("Pooled Particle System"); var ps = go.AddComponent<ParticleSystem>(); ps.Stop(true, ParticleSystemStopBehavior.StopEmittingAndClear);

var main = ps.main; main.duration = 1; main.startLifetime = 1; main.loop = false;

// This is used to return ParticleSystems to the pool when they have stopped. var returnToPool = go.AddComponent<ReturnToPool>(); returnToPool.pool = Pool;

return ps; }

// Called when an item is returned to the pool using Release void OnReturnedToPool(ParticleSystem system) { system.gameObject.SetActive(false); }

// Called when an item is taken from the pool using Get void OnTakeFromPool(ParticleSystem system) { system.gameObject.SetActive(true); }

// If the pool capacity is reached then any items returned will be destroyed. // We can control what the destroy behavior does, here we destroy the GameObject. void OnDestroyPoolObject(ParticleSystem system) { Destroy(system.gameObject); }

void OnGUI() { GUILayout.Label("Pool size: " + Pool.CountInactive); if (GUILayout.Button("Create Particles")) { var amount = Random.Range(1, 10); for (int i = 0; i < amount; ++i) { var ps = Pool.Get(); ps.transform.position = Random.insideUnitSphere * 10; ps.Play(); } } } }