Add ComponentMapper for faster retrieval of entity components

core/src/com/me/asteroids/screens/GameScreen.java

@@ -37,10 +37,10 @@ public class GameScreen extends Screen {
         engine.registerComponentClass(AccelerationComponent.class);
         engine.registerComponentClass(ModelComponent.class);
 
-        engine.registerSystem(new PlayerInputSystem());
+        engine.registerSystem(new PlayerInputSystem(engine));
-        engine.registerSystem(new MovementSystem());
+        engine.registerSystem(new MovementSystem(engine));
-        engine.registerSystem(new ScreenWrapSystem());
+        engine.registerSystem(new ScreenWrapSystem(engine));
-        engine.registerSystem(new ModelRenderSystem(graphics));
+        engine.registerSystem(new ModelRenderSystem(engine, graphics));
 
         engine.ready();
 

core/src/com/me/asteroids/systems/ModelRenderSystem.java

@@ -5,15 +5,20 @@ import com.badlogic.gdx.graphics.glutils.ShapeRenderer;
 import com.badlogic.gdx.math.Polygon;
 import com.me.asteroids.Graphics;
 import com.me.asteroids.components.ModelComponent;
+import com.me.common.ecs.ComponentMapper;
+import com.me.common.ecs.Engine;
 import com.me.common.ecs.Entity;
 import com.me.common.ecs.EntitySystem;
 
 public class ModelRenderSystem extends EntitySystem {
 
+    private ComponentMapper<ModelComponent> modelMapper;
+
     private ShapeRenderer renderer;
 
-    public ModelRenderSystem(Graphics graphics) {
+    public ModelRenderSystem(Engine engine, Graphics graphics) {
-        super(ModelComponent.class);
+        super(engine, ModelComponent.class);
+        this.modelMapper = engine.getComponentMapper(ModelComponent.class);
         this.renderer = graphics.getShapeRenderer();
     }
 
@@ -25,7 +30,7 @@ public class ModelRenderSystem extends EntitySystem {
 
     @Override
     public void processEntity(Entity entity, float dt) {
-        ModelComponent modelComponent = entity.getComponent(ModelComponent.class);
+        ModelComponent modelComponent = modelMapper.get(entity);
 
         Polygon model = modelComponent.model;
         renderer.polygon(model.getTransformedVertices());

core/src/com/me/asteroids/systems/MovementSystem.java

@@ -6,6 +6,8 @@ import com.me.asteroids.components.AccelerationComponent;
 import com.me.asteroids.components.ModelComponent;
 import com.me.asteroids.components.PositionComponent;
 import com.me.asteroids.components.VelocityComponent;
+import com.me.common.ecs.ComponentMapper;
+import com.me.common.ecs.Engine;
 import com.me.common.ecs.Entity;
 import com.me.common.ecs.EntitySystem;
 
@@ -13,20 +15,30 @@ public class MovementSystem extends EntitySystem {
 
     private Vector2 tmp = new Vector2();
 
-    public MovementSystem() {
+    private ComponentMapper<PositionComponent> positionMapper;
-        super(PositionComponent.class, VelocityComponent.class);
+    private ComponentMapper<VelocityComponent> velocityMapper;
+    private ComponentMapper<AccelerationComponent> accelMapper;
+    private ComponentMapper<ModelComponent> modelMapper;
+
+    public MovementSystem(Engine engine) {
+        super(engine, PositionComponent.class, VelocityComponent.class);
+
+        positionMapper = engine.getComponentMapper(PositionComponent.class);
+        velocityMapper = engine.getComponentMapper(VelocityComponent.class);
+        accelMapper = engine.getComponentMapper(AccelerationComponent.class);
+        modelMapper = engine.getComponentMapper(ModelComponent.class);
     }
 
     @Override
     public void processEntity(Entity entity, float dt) {
-        PositionComponent positionComponent = entity.getComponent(PositionComponent.class);
+        PositionComponent positionComponent = positionMapper.get(entity);
-        VelocityComponent velocityComponent = entity.getComponent(VelocityComponent.class);
+        VelocityComponent velocityComponent = velocityMapper.get(entity);
 
         Vector2 velocity = velocityComponent.velocity;
         float maxVelocity = velocityComponent.maxVelocity;
         Vector2 position = positionComponent.position;
 
-        AccelerationComponent accelComponent = entity.getComponent(AccelerationComponent.class);
+        AccelerationComponent accelComponent = accelMapper.get(entity);
         if (accelComponent != null && !accelComponent.acceleration.isZero()) {
             velocity.add(tmp.set(accelComponent.acceleration).scl(dt));
         }
@@ -36,7 +48,7 @@ public class MovementSystem extends EntitySystem {
             position.add(tmp.set(velocity).scl(dt));
         }
 
-        ModelComponent modelComponent = entity.getComponent(ModelComponent.class);
+        ModelComponent modelComponent = modelMapper.get(entity);
         if (modelComponent != null) {
             Polygon model = modelComponent.model;
             model.setPosition(position.x, position.y);

core/src/com/me/asteroids/systems/PlayerInputSystem.java

@@ -8,6 +8,8 @@ import com.me.asteroids.components.AccelerationComponent;
 import com.me.asteroids.components.PlayerComponent;
 import com.me.asteroids.components.PositionComponent;
 import com.me.asteroids.components.VelocityComponent;
+import com.me.common.ecs.ComponentMapper;
+import com.me.common.ecs.Engine;
 import com.me.common.ecs.Entity;
 import com.me.common.ecs.EntitySystem;
 
@@ -15,20 +17,28 @@ public class PlayerInputSystem extends EntitySystem {
 
     public Vector2 tmp = new Vector2(0, 1);
 
-    public PlayerInputSystem() {
+    private ComponentMapper<PositionComponent> positionMapper;
+    private ComponentMapper<VelocityComponent> velocityMapper;
+    private ComponentMapper<AccelerationComponent> accelMapper;
+
+    public PlayerInputSystem(Engine engine) {
         super(
+                engine,
                 PositionComponent.class,
                 VelocityComponent.class,
                 AccelerationComponent.class,
                 PlayerComponent.class
         );
+        positionMapper = engine.getComponentMapper(PositionComponent.class);
+        velocityMapper = engine.getComponentMapper(VelocityComponent.class);
+        accelMapper = engine.getComponentMapper(AccelerationComponent.class);
     }
 
     @Override
     public void processEntity(Entity entity, float dt) {
-        PositionComponent positionComponent = entity.getComponent(PositionComponent.class);
+        PositionComponent positionComponent = positionMapper.get(entity);
-        VelocityComponent velocityComponent = entity.getComponent(VelocityComponent.class);
+        VelocityComponent velocityComponent = velocityMapper.get(entity);
-        AccelerationComponent accelComponent = entity.getComponent(AccelerationComponent.class);
+        AccelerationComponent accelComponent = accelMapper.get(entity);
 
         if (Gdx.input.isKeyPressed(Input.Keys.D)) {
             positionComponent.rotation = Utils.rotate(positionComponent.rotation, -300 * dt);

core/src/com/me/asteroids/systems/ScreenWrapSystem.java

@@ -5,19 +5,26 @@ import com.badlogic.gdx.math.Vector2;
 import com.me.asteroids.Constants;
 import com.me.asteroids.components.ModelComponent;
 import com.me.asteroids.components.PositionComponent;
+import com.me.common.ecs.ComponentMapper;
+import com.me.common.ecs.Engine;
 import com.me.common.ecs.Entity;
 import com.me.common.ecs.EntitySystem;
 
 public class ScreenWrapSystem extends EntitySystem {
 
-    public ScreenWrapSystem() {
+    private ComponentMapper<PositionComponent> positionMapper;
-        super(PositionComponent.class, ModelComponent.class);
+    private ComponentMapper<ModelComponent> modelMapper;
+
+    public ScreenWrapSystem(Engine engine) {
+        super(engine, PositionComponent.class, ModelComponent.class);
+        positionMapper = engine.getComponentMapper(PositionComponent.class);
+        modelMapper = engine.getComponentMapper(ModelComponent.class);
     }
 
     @Override
     public void processEntity(Entity entity, float dt) {
-        PositionComponent positionComponent = entity.getComponent(PositionComponent.class);
+        PositionComponent positionComponent = positionMapper.get(entity);
-        ModelComponent modelComponent = entity.getComponent(ModelComponent.class);
+        ModelComponent modelComponent = modelMapper.get(entity);
 
         Vector2 position = positionComponent.position;
         Rectangle aabb = modelComponent.aabb;

core/src/com/me/common/ecs/ComponentMapper.java

@@ -0,0 +1,19 @@
+package com.me.common.ecs;
+
+public class ComponentMapper<T extends Component> {
+
+    private Engine engine;
+    private ComponentType type;
+    private Class<T> typeClass;
+
+    public ComponentMapper(Engine engine, Class<T> typeClass) {
+        this.engine = engine;
+        this.type = ComponentType.getComponentType(typeClass);
+        this.typeClass = typeClass;
+    }
+
+    public T get(Entity entity) {
+        return typeClass.cast(engine.getEntityComponent(entity, type));
+    }
+
+}

core/src/com/me/common/ecs/Engine.java

@@ -4,6 +4,9 @@ import com.badlogic.gdx.utils.Array;
 import com.me.common.ecs.event.Event;
 import com.me.common.ecs.event.Listener;
 
+import java.util.HashMap;
+import java.util.Map;
+
 public class Engine {
 
     private Array<Entity> entities;
@@ -16,6 +19,8 @@ public class Engine {
 
     private ListenerRegistry listenerRegistry;
 
+    private Map<Class<? extends Component>, ComponentMapper> componentMappers;
+
     public Engine() {
         this.entities = new Array<>();
         this.toActivate = new Array<>();
@@ -24,6 +29,7 @@ public class Engine {
 
         this.systems = new Array<>();
         this.listenerRegistry = new ListenerRegistry();
+        this.componentMappers = new HashMap<>();
     }
 
     public void registerComponentClass(Class<? extends Component> clazz) {
@@ -154,4 +160,18 @@ public class Engine {
         return clazz.cast(components[type.getId()].get(entity.getId()));
     }
 
+    protected Component getEntityComponent(Entity entity, ComponentType type) {
+        return components[type.getId()].get(entity.getId());
+    }
+
+    @SuppressWarnings("unchecked")
+    public <T extends Component> ComponentMapper<T> getComponentMapper(Class<T> typeClass) {
+        ComponentMapper<T> mapper = componentMappers.get(typeClass);
+        if (mapper == null) {
+            mapper = new ComponentMapper<>(this, typeClass);
+            componentMappers.put(typeClass, mapper);
+        }
+        return mapper;
+    }
+
 }

core/src/com/me/common/ecs/EntitySystem.java

@@ -6,11 +6,13 @@ public abstract class EntitySystem {
 
     private long typeBits;
 
+    protected Engine engine;
     protected Array<Entity> entities;
 
-    public EntitySystem(Class<? extends Component>... components) {
+    public EntitySystem(Engine engine, Class<? extends Component>... components) {
-        typeBits = ComponentType.getMaskBits(components);
+        this.engine = engine;
-        entities = new Array<>();
+        this.typeBits = ComponentType.getMaskBits(components);
+        this.entities = new Array<>(true, 16, Entity.class);
     }
 
     public void preProcessing() {}