+ plugins project

1 files changed, 120 insertions, 0 deletions

diff --git a/Plugins/MonoGame.Extended/source/MonoGame.Extended.Entities/EntityManager.cs b/Plugins/MonoGame.Extended/source/MonoGame.Extended.Entities/EntityManager.cs
new file mode 100644
index 0000000..5e1d28a
--- /dev/null
+++ b/Plugins/MonoGame.Extended/source/MonoGame.Extended.Entities/EntityManager.cs
@@ -0,0 +1,120 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.Specialized;
+using System.Diagnostics;
+using System.Linq;
+using Microsoft.Xna.Framework;
+using MonoGame.Extended.Collections;
+using MonoGame.Extended.Entities.Systems;
+
+namespace MonoGame.Extended.Entities
+{
+    public class EntityManager : UpdateSystem
+    {
+        private const int _defaultBagSize = 128;
+
+        public EntityManager(ComponentManager componentManager)
+        {
+            _componentManager = componentManager;
+            _addedEntities = new Bag<int>(_defaultBagSize);
+            _removedEntities = new Bag<int>(_defaultBagSize);
+            _changedEntities = new Bag<int>(_defaultBagSize);
+            _entityToComponentBits = new Bag<BitVector32>(_defaultBagSize);
+            _componentManager.ComponentsChanged += OnComponentsChanged;
+
+            _entityBag = new Bag<Entity>(_defaultBagSize);
+            _entityPool = new Pool<Entity>(() => new Entity(_nextId++, this, _componentManager), _defaultBagSize);
+        }
+
+        private readonly ComponentManager _componentManager;
+        private int _nextId;
+
+        public int Capacity => _entityBag.Capacity;
+        public IEnumerable<int> Entities => _entityBag.Where(e => e != null).Select(e => e.Id);
+        public int ActiveCount { get; private set; }
+
+        private readonly Bag<Entity> _entityBag;
+        private readonly Pool<Entity> _entityPool;
+        private readonly Bag<int> _addedEntities;
+        private readonly Bag<int> _removedEntities;
+        private readonly Bag<int> _changedEntities;
+        private readonly Bag<BitVector32> _entityToComponentBits;
+
+        public event Action<int> EntityAdded;
+        public event Action<int> EntityRemoved;
+        public event Action<int> EntityChanged;
+
+        public Entity Create()
+        {
+            var entity = _entityPool.Obtain();
+            var id = entity.Id;
+            Debug.Assert(_entityBag[id] == null);
+            _entityBag[id] = entity;
+            _addedEntities.Add(id);
+            _entityToComponentBits[id] = new BitVector32(0);
+            return entity;
+        }
+
+        public void Destroy(int entityId)
+        {
+            if (!_removedEntities.Contains(entityId))
+                _removedEntities.Add(entityId);
+        }
+
+        public void Destroy(Entity entity)
+        {
+            Destroy(entity.Id);
+        }
+
+        public Entity Get(int entityId)
+        {
+            return _entityBag[entityId];
+        }
+
+        public BitVector32 GetComponentBits(int entityId)
+        {
+            return _entityToComponentBits[entityId];
+        }
+
+        private void OnComponentsChanged(int entityId)
+        {
+            _changedEntities.Add(entityId);
+            _entityToComponentBits[entityId] = _componentManager.CreateComponentBits(entityId);
+            EntityChanged?.Invoke(entityId);
+        }
+
+        public override void Update(GameTime gameTime)
+        {
+            foreach (var entityId in _addedEntities)
+            {
+                _entityToComponentBits[entityId] = _componentManager.CreateComponentBits(entityId);
+                ActiveCount++;
+                EntityAdded?.Invoke(entityId);
+            }
+
+            foreach (var entityId in _changedEntities)
+            {
+                _entityToComponentBits[entityId] = _componentManager.CreateComponentBits(entityId);
+                EntityChanged?.Invoke(entityId);
+            }
+
+            foreach (var entityId in _removedEntities)
+            {
+                // we must notify subscribers before removing it from the pool
+                // otherwise an entity system could still be using the entity when the same id is obtained.
+                EntityRemoved?.Invoke(entityId);
+
+                var entity = _entityBag[entityId];
+                _entityBag[entityId] = null;
+                _componentManager.Destroy(entityId);
+                _entityToComponentBits[entityId] = default(BitVector32);
+                ActiveCount--;
+                _entityPool.Free(entity);
+            }
+
+            _addedEntities.Clear();
+            _removedEntities.Clear();
+            _changedEntities.Clear();
+        }
+    }
+}