Add afterburner.

core/src/com/me/asteroids/EntityFactory.java

@@ -62,13 +62,31 @@ public class EntityFactory {
         AccelerationComponent accel = new AccelerationComponent();
         accel.acceleration = new Vector2(0, 1f);
 
+        ModelComponent afterBurnerModel = new ModelComponent();
+        afterBurnerModel.model = new LineModel(Color.BLUE);
+        afterBurnerModel.model.setVertices(new float[] {
+                -2/16f, -5/16f,
+                0f, -0.8f,
+                2/16f, -5/16f
+        });
+
+        PositionComponent afterBurnerPosition = new PositionComponent();
+        afterBurnerPosition.position = new Vector2(Constants.HALF_WIDTH, Constants.HALF_HEIGHT);
+        afterBurnerPosition.rotation = 90;
+
         Entity player = createEntity(engine);
+        Entity afterBurner = createEntity(engine);
+        afterBurner.addComponent(afterBurnerPosition);
+        afterBurner.addComponent(velocity);
+        afterBurner.addComponent(afterBurnerModel);
+
         player.addComponent(position);
         player.addComponent(velocity);
         player.addComponent(model);
         player.addComponent(accel);
         player.addComponent(COLLIDER);
-        player.addComponent(new PlayerComponent());
+        player.addComponent(new PlayerComponent(afterBurner));
+
         return player;
     }
 

core/src/com/me/asteroids/components/PlayerComponent.java

@@ -1,7 +1,14 @@
 package com.me.asteroids.components;
 
 import com.me.common.ecs.Component;
+import com.me.common.ecs.Entity;
 
 public class PlayerComponent implements Component {
     // TODO: implement engine feature for tagging entities (as player, for e.g.)
+    public Entity afterBurner;
+
+    public PlayerComponent(Entity afterBurner) {
+        this.afterBurner = afterBurner;
+    }
+
 }

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

@@ -123,6 +123,7 @@ public class GameScreen extends Screen implements Listener {
         ComponentMapper<BulletComponent> bulletMapper;
         ComponentMapper<DebrisComponent> debrisMapper;
         ComponentMapper<AsteroidComponent> asteroidMapper;
+        ComponentMapper<PlayerComponent> playerMapper;
 
         EventListener(Engine engine) {
             this.positionMapper = engine.getComponentMapper(PositionComponent.class);
@@ -130,6 +131,7 @@ public class GameScreen extends Screen implements Listener {
             this.bulletMapper = engine.getComponentMapper(BulletComponent.class);
             this.debrisMapper = engine.getComponentMapper(DebrisComponent.class);
             this.asteroidMapper = engine.getComponentMapper(AsteroidComponent.class);
+            this.playerMapper = engine.getComponentMapper(PlayerComponent.class);
         }
 
         @EventHandler
@@ -172,6 +174,7 @@ public class GameScreen extends Screen implements Listener {
 
             if (asteroid.contains(player.getVertices()) || player.contains(asteroid.getVertices())) {
                 engine.callEvent(new PlayerDeathEvent(event.getPlayer()));
+                playerMapper.get(event.getPlayer()).afterBurner.deactivate();
                 event.getPlayer().deactivate();
                 for (Entity debris : EntityFactory.createDebris(engine, event.getPlayer())) {
                     debris.activate();

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

@@ -6,6 +6,7 @@ import com.badlogic.gdx.math.Vector2;
 import com.me.asteroids.EntityFactory;
 import com.me.asteroids.Utils;
 import com.me.asteroids.components.AccelerationComponent;
+import com.me.asteroids.components.ModelComponent;
 import com.me.asteroids.components.PlayerComponent;
 import com.me.asteroids.components.PositionComponent;
 import com.me.asteroids.components.VelocityComponent;
@@ -14,6 +15,8 @@ import com.me.common.ecs.Engine;
 import com.me.common.ecs.Entity;
 import com.me.common.ecs.EntitySystem;
 
+import static com.me.asteroids.Constants.rand;
+
 public class PlayerInputSystem extends EntitySystem {
 
     public Vector2 tmp = new Vector2(0, 1);
@@ -21,6 +24,7 @@ public class PlayerInputSystem extends EntitySystem {
     private ComponentMapper<PositionComponent> positionMapper;
     private ComponentMapper<VelocityComponent> velocityMapper;
     private ComponentMapper<AccelerationComponent> accelMapper;
+    private ComponentMapper<PlayerComponent> playerMapper;
 
     public PlayerInputSystem(Engine engine) {
         super(
@@ -33,6 +37,7 @@ public class PlayerInputSystem extends EntitySystem {
         positionMapper = engine.getComponentMapper(PositionComponent.class);
         velocityMapper = engine.getComponentMapper(VelocityComponent.class);
         accelMapper = engine.getComponentMapper(AccelerationComponent.class);
+        playerMapper = engine.getComponentMapper(PlayerComponent.class);
     }
 
     @Override
@@ -40,6 +45,7 @@ public class PlayerInputSystem extends EntitySystem {
         PositionComponent positionComponent = positionMapper.get(entity);
         VelocityComponent velocityComponent = velocityMapper.get(entity);
         AccelerationComponent accelComponent = accelMapper.get(entity);
+        PlayerComponent playerComponent = playerMapper.get(entity);
 
         boolean isLeftPressed = Gdx.input.isKeyPressed(Input.Keys.A);
         boolean isRightPressed = Gdx.input.isKeyPressed(Input.Keys.D);
@@ -54,9 +60,21 @@ public class PlayerInputSystem extends EntitySystem {
         Vector2 acceleration = accelComponent.acceleration;
         Vector2 velocity = velocityComponent.velocity;
 
+        playerComponent.afterBurner.getComponent(ModelComponent.class).model.setPosition(positionComponent.position);
+
         if (Gdx.input.isKeyPressed(Input.Keys.W)) {
             acceleration.set(Utils.setUnitVectorAngle(tmp, positionComponent.rotation).scl(12.5f));
+
+            if (rand.nextFloat() < 0.85) {
+                PositionComponent afterBurnerPosition = positionMapper.get(playerComponent.afterBurner);
+                afterBurnerPosition.position.set(positionComponent.position);
+                afterBurnerPosition.rotation = positionComponent.rotation;
+                playerComponent.afterBurner.activate();
             } else {
+                playerComponent.afterBurner.deactivate();
+            }
+        } else {
+            playerComponent.afterBurner.deactivate();
             if (!velocity.isZero(1f)) {
                 acceleration.set(Utils.setUnitVectorAngleRad(tmp, velocity.angleRad()).scl(-2.5f));
             } else {