Added Unitys native object pool implementation. Updated readme. Refactored object pooling code

Author: Habrador

Assets/Patterns/18. Object Pool/Gun/Scripts.meta renamed to Assets/Patterns/18. Object Pool/Gun/Object pools.meta

@@ -0,0 +1,36 @@
+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+namespace ObjectPool.Gun
+{
+    //Parent bullet class to avoid code duplication
+    public class BulletBase : MonoBehaviour
+    {
+        private readonly float bulletSpeed = 10f;
+
+        private readonly float deactivationDistance = 30f;
+
+
+
+        protected void MoveBullet()
+        {
+            transform.Translate(bulletSpeed * Time.deltaTime * Vector3.forward);
+        }
+
+
+
+        protected bool IsBulletDead()
+        {
+            bool isDead = false;
+        
+            //The gun is at 0
+            if (Vector3.SqrMagnitude(Vector3.zero - transform.position) > deactivationDistance * deactivationDistance)
+            {
+                isDead = true;
+            }
+
+            return isDead;
+        }
+    }
+}

Assets/Patterns/18. Object Pool/Gun/Object pools/BulletBase.cs

@@ -2,22 +2,29 @@
 using System.Collections.Generic;
 using UnityEngine;
 
+
 namespace ObjectPool.Gun
 {
     public class GunController : MonoBehaviour
     {
-        //Pick which object pool you want to use
-        public BulletObjectPool bulletPool;
+        //Pick which object pool you want to use by activating it in the hierarchy and drag it to its uncommented slot 
+        
+        //Simplest possible object pool
+        //public BulletObjectPoolSimple bulletPool;
 
+        //Optimized object pool
         //public BulletObjectPoolOptimized bulletPool;
 
+        //Unity's native object pool
+        public BulletObjectPoolUnity bulletPool; 
+
 
         //Private
-        private float rotationSpeed = 60f;
+        private readonly float rotationSpeed = 60f;
 
         private float fireTimer;
 
-        private float fireInterval = 0.1f;
+        private readonly float fireInterval = 0.1f;
 
 
 
@@ -35,7 +42,7 @@ void Start()
 
         void Update()
         {
-            //Rotate gun
+            //Rotate gun with A and D keys
             if (Input.GetKey(KeyCode.A))
             {
                 transform.Rotate(Vector3.up, -rotationSpeed * Time.deltaTime);
@@ -46,17 +53,15 @@ void Update()
             }
 
 
-            //Fire gun
+            //Fire gun with spacebar
             if (Input.GetKey(KeyCode.Space) && fireTimer > fireInterval)
             {
                 fireTimer = 0f;
 
-                GameObject newBullet = GetABullet();
+                GameObject newBullet = bulletPool.GetBullet();
 
                 if (newBullet != null)
                 {
-                    newBullet.SetActive(true);
-
                     newBullet.transform.forward = transform.forward;
 
                     //Move the bullet to the tip of the gun or it will look strange if we rotate while firing
@@ -72,14 +77,5 @@ void Update()
             //Update the time since we last fired a bullet
             fireTimer += Time.deltaTime;
         }
-
-
-
-        private GameObject GetABullet()
-        {
-            GameObject bullet = bulletPool.GetBullet();
-
-            return bullet;
-        }
     }
 }

Assets/Patterns/18. Object Pool/Gun/Object pools/BulletBase.cs.meta

@@ -0,0 +1,16 @@
+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+namespace ObjectPool.Gun
+{
+    //Parent object pool class to avoid code duplication
+    public class ObjectPoolBase : MonoBehaviour
+    {
+        //How many bullets do we start with when the game starts
+        protected const int INITIAL_POOL_SIZE = 10;
+
+        //Sometimes it can be good to put a limit to how many bullets we can instantiate or we might get millions of them
+        protected const int MAX_POOL_SIZE = 20;
+    }
+}

Assets/Patterns/18. Object Pool/Gun/Scripts/GunController.cs renamed to Assets/Patterns/18. Object Pool/Gun/Object pools/GunController.cs

@@ -4,27 +4,21 @@
 
 namespace ObjectPool.Gun
 {
-    //Has to inherit from MonoBehaviour so we can use Instantiate()
-    public class BulletObjectPoolOptimized : MonoBehaviour
+    //This object pool is slightly more complicated to understand but has better performance
+    public class BulletObjectPoolOptimized : ObjectPoolBase
     {
         //The bullet prefab we instantiate
         public MoveBulletOptimized bulletPrefab;
 
         //Store the pooled bullets here
-        //Instead of GameObject, use MoveBulletOptimized so we dont need a million GetComponent because we need access to that script
-        private List<MoveBulletOptimized> bullets = new List<MoveBulletOptimized>();
-
-        //How many bullets do we start with when the game starts
-        private const int INITIAL_POOL_SIZE = 10;
-
-        //Sometimes it can be good to put a limit to how many bullets we can isntantiate or we might get millions of them
-        private const int MAX_POOL_SIZE = 20;
+        private readonly List<MoveBulletOptimized> bullets = new ();
 
         //First available bullet, so we don't have to search a list to find it
         //Instead we create a linked-list where all unused bullets are linked together
         private MoveBulletOptimized firstAvailable;
 
 
+
         private void Start()
         {
             if (bulletPrefab == null)
@@ -50,10 +44,11 @@ private void Start()
             }
 
             //The last one terminates the linked-list
-            bullets[bullets.Count - 1].next = null;
+            bullets[^1].next = null;
         }
 
 
+
         //Generate a single new bullet and put it in the list
         private void GenerateBullet()
         {
@@ -68,6 +63,7 @@ private void GenerateBullet()
         }
 
 
+
         //A bullet has been deactivated so we need to add it to the linked list
         public void ConfigureDeactivatedBullet(MoveBulletOptimized deactivatedObj)
         {
@@ -78,6 +74,7 @@ public void ConfigureDeactivatedBullet(MoveBulletOptimized deactivatedObj)
         }
 
 
+
         //Try to get a bullet
         public GameObject GetBullet()
         {
@@ -90,7 +87,7 @@ public GameObject GetBullet()
                     GenerateBullet();
 
                     //The new bullet is last in the list so get it
-                    MoveBulletOptimized lastBullet = bullets[bullets.Count - 1];
+                    MoveBulletOptimized lastBullet = bullets[^1];
 
                     //Add it to the linked list by reusing the method we use for deactivated bullets, so it will now be the first bullet in the linked-list
                     ConfigureDeactivatedBullet(lastBullet);
@@ -106,7 +103,11 @@ public GameObject GetBullet()
 
             firstAvailable = newBullet.next;
 
-            return newBullet.gameObject;
+            GameObject newBulletGO = newBullet.gameObject;
+
+            newBulletGO.SetActive(true);
+
+            return newBulletGO;
         }
     }
 }

Assets/Patterns/18. Object Pool/Gun/Scripts/GunController.cs.meta renamed to Assets/Patterns/18. Object Pool/Gun/Object pools/GunController.cs.meta

@@ -4,24 +4,20 @@
 
 namespace ObjectPool.Gun
 {
-    public class MoveBulletOptimized : MonoBehaviour
+    public class MoveBulletOptimized : BulletBase
     {
-        private float bulletSpeed = 10f;
-
-        private float deactivationDistance = 30f;
-
         //Needed to optimize object pooling
         [System.NonSerialized] public MoveBulletOptimized next;
         //Instead of using this dependency you could use the Observer pattern because other things may happen when the bullet dies
         [System.NonSerialized] public BulletObjectPoolOptimized objectPool;
 
 
         void Update()
-        {        
-            transform.Translate(Vector3.forward * bulletSpeed * Time.deltaTime);
+        {
+            MoveBullet();
 
             //Deactivate the bullet when it's far away
-            if (Vector3.SqrMagnitude(transform.position) > deactivationDistance * deactivationDistance)
+            if (IsBulletDead())
             {
                 //In the optimized version, we have to tell the object pool that this bullet has been deactivated
                 objectPool.ConfigureDeactivatedBullet(this);

Assets/Patterns/18. Object Pool/Gun/Object pools/ObjectPoolBase.cs

@@ -11,7 +11,7 @@ GameObject:
   - component: {fileID: 747956090910683963}
   - component: {fileID: 747956090910683964}
   m_Layer: 0
-  m_Name: Bullet
+  m_Name: Bullet Prefab Simple
   m_TagString: Untagged
   m_Icon: {fileID: 0}
   m_NavMeshLayer: 0

Assets/Patterns/18. Object Pool/Gun/Object pools/ObjectPoolBase.cs.meta

@@ -4,21 +4,16 @@
 
 namespace ObjectPool.Gun
 {
-    //Has to inherit from MonoBehaviour so we can use Instantiate()
-    public class BulletObjectPool : MonoBehaviour
+    //Simplest possible object pool
+    public class BulletObjectPoolSimple : ObjectPoolBase
     {
         //The bullet prefab we instantiate
-        public GameObject bulletPrefab;
-        
-        //Store the pooled bullets here
-        private List<GameObject> bullets = new List<GameObject>();
-
-        //How many bullets do we start with when the game starts
-        private const int INITIAL_POOL_SIZE = 10;
+        public MoveBullet bulletPrefab;
 
-        //Sometimes it can be good to put a limit to how many bullets we can isntantiate or we might get millions of them
-        private const int MAX_POOL_SIZE = 20;
+        //Store the pooled bullets here
+        private readonly List<GameObject> bullets = new ();
 
+        
 
         private void Start()
         {
@@ -35,28 +30,30 @@ private void Start()
         }
 
 
+
         //Generate a single new bullet and put it in list
         private void GenerateBullet()
         {
-            GameObject newBullet = Instantiate(bulletPrefab, transform);
+            GameObject newBullet = Instantiate(bulletPrefab.gameObject, transform);
 
             newBullet.SetActive(false);
 
             bullets.Add(newBullet);
         }
 
 
-        //Try to get a bullet
+
+        //Get a bullet from the pool
         public GameObject GetBullet()
         {
             //Try to find an inactive bullet
-            for (int i = 0; i < bullets.Count; i++)
+            foreach (GameObject bullet in bullets)
             {
-                GameObject thisBullet = bullets[i];
-
-                if (!thisBullet.activeInHierarchy)
-                {                
-                    return thisBullet;
+                if (!bullet.activeInHierarchy)
+                {
+                    bullet.SetActive(true);
+                
+                    return bullet;
                 }
             }
 
@@ -66,7 +63,9 @@ public GameObject GetBullet()
                 GenerateBullet();
 
                 //The new bullet is last in the list so get it
-                GameObject lastBullet = bullets[bullets.Count - 1];
+                GameObject lastBullet = bullets[^1];
+
+                lastBullet.SetActive(true);
 
                 return lastBullet;
             }

Assets/Patterns/18. Object Pool/Gun/Scripts/Optimized.meta renamed to Assets/Patterns/18. Object Pool/Gun/Object pools/Optimized.meta

@@ -0,0 +1,20 @@
+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+namespace ObjectPool.Gun
+{
+    public class MoveBullet : BulletBase
+    {
+        void Update()
+        {
+            MoveBullet();
+            
+            //Deactivate the bullet when it's far away
+            if (IsBulletDead())
+            {
+                gameObject.SetActive(false);
+            }
+        }
+    }
+}