working on an entity component system

Source/Demos/Demo.Platformer/Demo.Platformer.csproj

@@ -36,9 +36,16 @@
     <ApplicationIcon>Icon.ico</ApplicationIcon>
   </PropertyGroup>
   <ItemGroup>
+    <Compile Include="Entities\Components\EntityComponent.cs" />
+    <Compile Include="Entities\Components\SpriteAnimatorComponent.cs" />
     <Compile Include="Entities\Components\SpriteComponent.cs" />
     <Compile Include="Entities\Entity.cs" />
-    <Compile Include="Entities\EntityGameComponent.cs" />
+    <Compile Include="Entities\EntityComponentSystem.cs" />
+    <Compile Include="Entities\Systems\SpriteAnimatorComponentSystem.cs" />
+    <Compile Include="Entities\Systems\UpdatableComponentSystem.cs" />
+    <Compile Include="Entities\Systems\ComponentSystem.cs" />
+    <Compile Include="Entities\Systems\DrawableComponentSystem.cs" />
+    <Compile Include="Entities\Systems\SpriteBatchComponentSystem.cs" />
     <Compile Include="Game1.cs" />
     <Compile Include="Program.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
@@ -74,6 +81,7 @@
       <Name>MonoGame.Extended</Name>
     </ProjectReference>
   </ItemGroup>
+  <ItemGroup />
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <Import Project="$(MSBuildExtensionsPath)\MonoGame\v3.0\MonoGame.Content.Builder.targets" />
   <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 

Source/Demos/Demo.Platformer/Entities/Components/EntityComponent.cs

@@ -0,0 +1,11 @@
+namespace Demo.Platformer.Entities.Components
+{
+    public abstract class EntityComponent
+    {
+        protected EntityComponent()
+        {
+        }
+
+        public Entity Entity { get; internal set; }
+    }
+}

Source/Demos/Demo.Platformer/Entities/Components/SpriteAnimatorComponent.cs

@@ -0,0 +1,17 @@
+using MonoGame.Extended.Animations.SpriteSheets;
+
+namespace Demo.Platformer.Entities.Components
+{
+    public class SpriteAnimatorComponent : EntityComponent
+    {
+        public SpriteAnimatorComponent(SpriteSheetAnimationFactory animationFactory, string playAnimation = null)
+        {
+            Animator = new SpriteSheetAnimator(animationFactory);
+
+            if (playAnimation != null)
+                Animator.Play(playAnimation);
+        }
+
+        public SpriteSheetAnimator Animator { get; }
+    }
+}

Source/Demos/Demo.Platformer/Entities/Components/SpriteComponent.cs

@@ -1,23 +1,10 @@
 using Microsoft.Xna.Framework;
 using Microsoft.Xna.Framework.Graphics;
-using MonoGame.Extended.SceneGraphs;
 using MonoGame.Extended.TextureAtlases;
 
 namespace Demo.Platformer.Entities.Components
 {
-    public abstract class EntityComponent
-    {
-        protected EntityComponent()
-        {
-        }
-
-        public Entity Entity { get; internal set; }
-
-        public abstract void Update(float deltaTime);
-        public abstract void Draw(SpriteBatch spriteBatch);
-    }
-
-    public class SpriteComponent : EntityComponent, ISpriteBatchDrawable
+    public class SpriteComponent : EntityComponent
     {
         public SpriteComponent(TextureRegion2D textureRegion)
         {
@@ -26,24 +13,19 @@ namespace Demo.Platformer.Entities.Components
             Color = Color.White;
             Origin = new Vector2(textureRegion.Size.Width, textureRegion.Size.Height)*0.5f;
             Effect = SpriteEffects.None;
+            Alpha = 1.0f;
+            Depth = 0.0f;
         }
 
         public bool IsVisible { get; set; }
         public TextureRegion2D TextureRegion { get; set; }
-        public Color Color { get; }
-        public Vector2 Origin { get; }
-        public SpriteEffects Effect { get; }
+        public Color Color { get; set; }
+        public Vector2 Origin { get; set; }
+        public SpriteEffects Effect { get; set; }
         public Vector2 Position => Entity.Position;
         public float Rotation => Entity.Rotation;
         public Vector2 Scale => Entity.Scale;
-
-        public override void Update(float deltaTime)
-        {
-        }
-
-        public override void Draw(SpriteBatch spriteBatch)
-        {
-            spriteBatch.Draw(TextureRegion, Position, Color, Rotation, Origin, Scale, Effect, 0);
-        }
+        public float Alpha { get; set; }
+        public float Depth { get; set; }
     }
 }

Source/Demos/Demo.Platformer/Entities/Entity.cs

@@ -1,4 +1,5 @@
-using Demo.Platformer.Entities.Components;
+using System;
+using Demo.Platformer.Entities.Components;
 using Microsoft.Xna.Framework;
 using MonoGame.Extended;
 
@@ -6,24 +7,51 @@ namespace Demo.Platformer.Entities
 {
     public class Entity : IMovable, IRotatable, IScalable
     {
-        private readonly IEntityManager _entityManager;
+        private readonly EntityComponentSystem _entityComponentSystem;
 
-        public Entity(IEntityManager entityManager, long id)
+        public Entity(EntityComponentSystem entityComponentSystem, long id, string name)
         {
-            _entityManager = entityManager;
+            _entityComponentSystem = entityComponentSystem;
+
             Id = id;
+            Name = name;
+            Position = Vector2.Zero;
+            Rotation = 0;
             Scale = Vector2.One;
         }
 
         public long Id { get; }
+        public string Name { get; }
         public Vector2 Position { get; set; }
         public float Rotation { get; set; }
         public Vector2 Scale { get; set; }
 
+        public override string ToString()
+        {
+            return Name;
+        }
+
         public void AttachComponent(EntityComponent component)
         {
+            if (component.Entity != null)
+                throw new InvalidOperationException("Component already attached to another entity");
+
             component.Entity = this;
-            _entityManager.AttachComponent(component);
+            _entityComponentSystem.AttachComponent(component);
+        }
+
+        public void DetachComponent(EntityComponent component)
+        {
+            if (component.Entity != this)
+                throw new InvalidOperationException("Component not attached to entity");
+
+            component.Entity = null;
+            _entityComponentSystem.DetachComponent(component);
+        }
+
+        public void Destroy()
+        {
+            _entityComponentSystem.DestroyEntity(this);
         }
     }
 }

Source/Demos/Demo.Platformer/Entities/EntityComponentSystem.cs

@@ -0,0 +1,79 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Demo.Platformer.Entities.Components;
+using Demo.Platformer.Entities.Systems;
+using Microsoft.Xna.Framework;
+
+namespace Demo.Platformer.Entities
+{
+    public class EntityComponentSystem
+    {
+        public EntityComponentSystem() 
+        {
+            _entities = new List<Entity>();
+            _components = new List<EntityComponent>();
+            _systems = new List<ComponentSystem>();
+            _nextEntityId = 1;
+        }
+
+        private readonly List<ComponentSystem> _systems;
+        private readonly List<Entity> _entities;
+        private readonly List<EntityComponent> _components;
+        private long _nextEntityId;
+
+        public void RegisterSystem(ComponentSystem system)
+        {
+            if (system.EntityComponentSystem != null)
+                throw new InvalidOperationException("Component system already registered");
+
+            system.EntityComponentSystem = this;
+            _systems.Add(system);
+        }
+
+        public Entity CreateEntity(string name)
+        {
+            var entity = new Entity(this, _nextEntityId, name);
+            _entities.Add(entity);
+            _nextEntityId++;
+            return entity;
+        }
+
+        public Entity FindEntity(string name)
+        {
+            return _entities.FirstOrDefault(e => e.Name == name);
+        }
+
+        public void DestroyEntity(Entity entity)
+        {
+            _entities.Remove(entity);
+        }
+
+        public void AttachComponent(EntityComponent component)
+        {
+            _components.Add(component);
+        }
+
+        public void DetachComponent(EntityComponent component)
+        {
+            _components.Remove(component);
+        }
+
+        internal IEnumerable<T> GetComponents<T>()
+        {
+            return _components.OfType<T>();
+        }
+
+        public void Update(GameTime gameTime)
+        {
+            foreach (var componentSystem in _systems.OfType<UpdatableComponentSystem>())
+                componentSystem.Update(gameTime);
+        }
+
+        public void Draw(GameTime gameTime)
+        {
+            foreach (var componentSystem in _systems.OfType<DrawableComponentSystem>())
+                componentSystem.Draw(gameTime);
+        }
+    }
+}

Source/Demos/Demo.Platformer/Entities/EntityGameComponent.cs

@@ -1,82 +0,0 @@
-using System.Collections.Generic;
-using Demo.Platformer.Entities.Components;
-using Microsoft.Xna.Framework;
-using Microsoft.Xna.Framework.Graphics;
-using MonoGame.Extended;
-
-namespace Demo.Platformer.Entities
-{
-    public interface IEntityManager
-    {
-        void AttachComponent(EntityComponent component);
-        void DetachComponent(EntityComponent component);
-    }
-
-    public class EntityGameComponent : DrawableGameComponent, IEntityManager
-    {
-        public EntityGameComponent(Game game) 
-            : base(game)
-        {
-            _entities = new List<Entity>();
-            _components = new List<EntityComponent>();
-            _nextEntityId = 1;
-        }
-
-        private SpriteBatch _spriteBatch;
-        private readonly List<Entity> _entities;
-        private readonly List<EntityComponent> _components;
-        private long _nextEntityId;
-
-        public override void Initialize()
-        {
-            base.Initialize();
-
-            _spriteBatch = new SpriteBatch(GraphicsDevice);
-        }
-
-        public Entity CreateEntity()
-        {
-            var entity = new Entity(this, _nextEntityId);
-            _entities.Add(entity);
-            _nextEntityId++;
-            return entity;
-        }
-
-        public void DestroyEntity(Entity entity)
-        {
-            _entities.Remove(entity);
-        }
-
-        public void AttachComponent(EntityComponent component)
-        {
-            _components.Add(component);
-        }
-
-        public void DetachComponent(EntityComponent component)
-        {
-            _components.Remove(component);
-        }
-
-        public override void Update(GameTime gameTime)
-        {
-            base.Update(gameTime);
-
-            var deltaTime = gameTime.GetElapsedSeconds();
-
-            foreach (var entityComponent in _components)
-                entityComponent.Update(deltaTime);
-        }
-
-        public override void Draw(GameTime gameTime)
-        {
-            base.Draw(gameTime);
-
-            _spriteBatch.Begin();
-
-            foreach (var entityComponent in _components)
-                entityComponent.Draw(_spriteBatch);
-
-            _spriteBatch.End();
-        }
-    }
-}

Source/Demos/Demo.Platformer/Entities/Systems/ComponentSystem.cs

@@ -0,0 +1,18 @@
+using System.Collections.Generic;
+
+namespace Demo.Platformer.Entities.Systems
+{
+    public abstract class ComponentSystem
+    {
+        protected ComponentSystem()
+        {
+        }
+
+        internal EntityComponentSystem EntityComponentSystem { get; set; }
+
+        protected IEnumerable<T> GetComponents<T>()
+        {
+            return EntityComponentSystem.GetComponents<T>();
+        }
+    }
+}

Source/Demos/Demo.Platformer/Entities/Systems/DrawableComponentSystem.cs

@@ -0,0 +1,9 @@
+using Microsoft.Xna.Framework;
+
+namespace Demo.Platformer.Entities.Systems
+{
+    public abstract class DrawableComponentSystem : ComponentSystem
+    {
+        public abstract void Draw(GameTime gameTime);
+    }
+}

Source/Demos/Demo.Platformer/Entities/Systems/SpriteAnimatorComponentSystem.cs

@@ -0,0 +1,20 @@
+using Demo.Platformer.Entities.Components;
+using Microsoft.Xna.Framework;
+
+namespace Demo.Platformer.Entities.Systems
+{
+    public class SpriteAnimatorComponentSystem : UpdatableComponentSystem
+    {
+        public SpriteAnimatorComponentSystem()
+        {
+        }
+
+        public override void Update(GameTime gameTime)
+        {
+            var components = GetComponents<SpriteAnimatorComponent>();
+
+            foreach (var component in components)
+                component.Animator.Update(gameTime);
+        }
+    }
+}

Source/Demos/Demo.Platformer/Entities/Systems/SpriteBatchComponentSystem.cs

@@ -0,0 +1,36 @@
+using Demo.Platformer.Entities.Components;
+using Microsoft.Xna.Framework;
+using Microsoft.Xna.Framework.Graphics;
+
+namespace Demo.Platformer.Entities.Systems
+{
+    public class SpriteBatchComponentSystem : DrawableComponentSystem
+    {
+        public SpriteBatchComponentSystem(GraphicsDevice graphicsDevice)
+        {
+            _spriteBatch = new SpriteBatch(graphicsDevice);
+        }
+
+        private readonly SpriteBatch _spriteBatch;
+
+        public override void Draw(GameTime gameTime)
+        {
+            var spriteComponents = GetComponents<SpriteComponent>();
+
+            _spriteBatch.Begin();
+
+            foreach (var sprite in spriteComponents)
+            {
+                if (sprite.IsVisible)
+                {
+                    var texture = sprite.TextureRegion.Texture;
+                    var sourceRectangle = sprite.TextureRegion.Bounds;
+
+                    _spriteBatch.Draw(texture, sprite.Position, sourceRectangle, sprite.Color * sprite.Alpha, sprite.Rotation, sprite.Origin,
+                        sprite.Scale, sprite.Effect, sprite.Depth);
+                }
+            }
+            _spriteBatch.End();
+        }
+    }
+}

Source/Demos/Demo.Platformer/Entities/Systems/UpdatableComponentSystem.cs

@@ -0,0 +1,9 @@
+using Microsoft.Xna.Framework;
+
+namespace Demo.Platformer.Entities.Systems
+{
+    public abstract class UpdatableComponentSystem : ComponentSystem
+    {
+        public abstract void Update(GameTime gameTime);
+    }
+}

Source/Demos/Demo.Platformer/Game1.cs

@@ -1,12 +1,12 @@
 using Demo.Platformer.Entities;
 using Demo.Platformer.Entities.Components;
+using Demo.Platformer.Entities.Systems;
 using Microsoft.Xna.Framework;
 using Microsoft.Xna.Framework.Graphics;
 using Microsoft.Xna.Framework.Input;
 using MonoGame.Extended;
 using MonoGame.Extended.Animations.SpriteSheets;
 using MonoGame.Extended.Maps.Tiled;
-using MonoGame.Extended.Sprites;
 using MonoGame.Extended.TextureAtlases;
 using MonoGame.Extended.ViewportAdapters;
 
@@ -16,16 +16,9 @@ namespace Demo.Platformer
     {
         // ReSharper disable once NotAccessedField.Local
         private readonly GraphicsDeviceManager _graphicsDeviceManager;
-        private SpriteBatch _spriteBatch;
         private Camera2D _camera;
         private TiledMap _tiledMap;
-        private Sprite _sprite;
-        private SpriteSheetAnimator _animator;
-        private EntityGameComponent _entityManager;
-
-        //private Sprite _sprite0;
-        //private Sprite _sprite1;
-        //private Texture2D _logo;
+        private EntityComponentSystem _entityComponentSystem;
 
         public Game1()
         {
@@ -37,36 +30,33 @@ namespace Demo.Platformer
 
         protected override void Initialize()
         {
-            Components.Add(_entityManager = new EntityGameComponent(this));
+            _entityComponentSystem = new EntityComponentSystem();
+            _entityComponentSystem.RegisterSystem(new SpriteBatchComponentSystem(GraphicsDevice));
+            _entityComponentSystem.RegisterSystem(new SpriteAnimatorComponentSystem());
 
             base.Initialize();
         }
 
         protected override void LoadContent()
         {
-            _spriteBatch = new SpriteBatch(GraphicsDevice);
-
-            //_logo = Content.Load<Texture2D>("logo-square-128");
-
             var viewportAdapter = new BoxingViewportAdapter(Window, GraphicsDevice, 800, 480);
             _camera = new Camera2D(viewportAdapter);
 
+            // first load our resources
             var texture = Content.Load<Texture2D>("tiny-characters");
             var atlas = TextureAtlas.Create(texture, 32, 32, 15);
             var animationFactory = new SpriteSheetAnimationFactory(atlas);
+            animationFactory.Add("idle", new SpriteSheetAnimationData(new[] { 0, 1, 2, 3 }, isReversed: true));
 
-            var entity = _entityManager.CreateEntity();
+            // let's build our dude entity
+            var entity = _entityComponentSystem.CreateEntity("dude");
             entity.AttachComponent(new SpriteComponent(atlas[0]));
+            entity.AttachComponent(new SpriteAnimatorComponent(animationFactory, "idle"));
             entity.Position = new Vector2(300, 300);
 
-            animationFactory.Add("idle", new SpriteSheetAnimationData(new[] {0, 1, 2, 3}, isReversed: true));
-            _animator = new SpriteSheetAnimator(animationFactory);
-            _animator.Play("idle");
-            _sprite = _animator.CreateSprite(position: new Vector2(116, 273));
-            //_sprite1 = _animator.CreateSprite(position: new Vector2(132, 273));
             _tiledMap = Content.Load<TiledMap>("level-1");
 
-            var viewport = GraphicsDevice.Viewport;
+            //var viewport = GraphicsDevice.Viewport;
             //_alphaTestEffect = new AlphaTestEffect(GraphicsDevice)
             //{
             //    Projection =
@@ -83,19 +73,21 @@ namespace Demo.Platformer
 
         protected override void Update(GameTime gameTime)
         {
-            var deltaTime = (float)gameTime.ElapsedGameTime.TotalSeconds;
+            //var deltaTime = (float)gameTime.ElapsedGameTime.TotalSeconds;
             var keyboardState = Keyboard.GetState();
 
             if (keyboardState.IsKeyDown(Keys.Escape))
                 Exit();
 
-            if (keyboardState.IsKeyDown(Keys.D) || keyboardState.IsKeyDown(Keys.Right))
-                _sprite.Position += new Vector2(150, 0) * deltaTime;
+            //if (keyboardState.IsKeyDown(Keys.D) || keyboardState.IsKeyDown(Keys.Right))
+            //    _sprite.Position += new Vector2(150, 0) * deltaTime;
 
-            if (keyboardState.IsKeyDown(Keys.A) || keyboardState.IsKeyDown(Keys.Left))
-                _sprite.Position -= new Vector2(150, 0) * deltaTime;
+            //if (keyboardState.IsKeyDown(Keys.A) || keyboardState.IsKeyDown(Keys.Left))
+            //    _sprite.Position -= new Vector2(150, 0) * deltaTime;
 
-            _animator.Update(deltaTime);
+            //_animator.Update(deltaTime);
+
+            _entityComponentSystem.Update(gameTime);
 
             base.Update(gameTime);
         }
@@ -107,7 +99,7 @@ namespace Demo.Platformer
             var viewMatrix = _camera.GetViewMatrix();
 
             GraphicsDevice.Clear(Color.CornflowerBlue);
-            
+
             //_spriteBatch.Begin(
             //    sortMode: SpriteSortMode.FrontToBack, 
             //    samplerState: SamplerState.PointClamp, 
@@ -123,9 +115,11 @@ namespace Demo.Platformer
             
             _tiledMap.Draw(viewMatrix);
 
-            _spriteBatch.Begin(samplerState: SamplerState.PointClamp, transformMatrix: viewMatrix);
-            _spriteBatch.Draw(_sprite);
-            _spriteBatch.End();
+            //_spriteBatch.Begin(samplerState: SamplerState.PointClamp, transformMatrix: viewMatrix);
+            //_spriteBatch.Draw(_sprite);
+            //_spriteBatch.End();
+
+            _entityComponentSystem.Draw(gameTime);
 
             base.Draw(gameTime);
         }

Source/MonoGame.Extended/IDraw.cs

@@ -1,9 +0,0 @@
-using Microsoft.Xna.Framework;
-
-namespace MonoGame.Extended
-{
-    public interface IDraw
-    {
-        void Draw(GameTime gameTime);
-    }
-}

Source/MonoGame.Extended/MonoGame.Extended.csproj

@@ -111,7 +111,6 @@
     <Compile Include="Content\ContentReaderExtensions.cs" />
     <Compile Include="EventHandlerExtensions.cs" />
     <Compile Include="GameTimeExtensions.cs" />
-    <Compile Include="IDraw.cs" />
     <Compile Include="IMovable.cs" />
     <Compile Include="InputListeners\GamePadEventArgs.cs" />
     <Compile Include="InputListeners\GamePadListener.cs" />

Source/MonoGame.Extended/Screens/Screen.cs

@@ -3,7 +3,7 @@ using Microsoft.Xna.Framework;
 
 namespace MonoGame.Extended.Screens
 {
-    public abstract class Screen : IDraw, IDisposable
+    public abstract class Screen : IDisposable
     {
         protected Screen()
         {