Delete bullets when they leave the screen

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

@@ -3,6 +3,7 @@ package com.me.asteroids;
 import com.badlogic.gdx.math.Polygon;
 import com.badlogic.gdx.math.Vector2;
 import com.me.asteroids.components.AccelerationComponent;
+import com.me.asteroids.components.BulletComponent;
 import com.me.asteroids.components.ModelComponent;
 import com.me.asteroids.components.PlayerComponent;
 import com.me.asteroids.components.PositionComponent;
@@ -67,6 +68,7 @@ public class EntityFactory {
         bullet.addComponent(position);
         bullet.addComponent(velocity);
         bullet.addComponent(model);
+        bullet.addComponent(new BulletComponent());
         return bullet;
     }
 

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

@@ -0,0 +1,6 @@
+package com.me.asteroids.components;
+
+import com.me.common.ecs.Component;
+
+public class BulletComponent implements Component {
+}

core/src/com/me/asteroids/events/ScreenWrapEvent.java

@@ -0,0 +1,18 @@
+package com.me.asteroids.events;
+
+import com.me.common.ecs.Entity;
+import com.me.common.ecs.event.Event;
+
+/**
+ * Called when an entity is about to wrap around the screen.
+ * If cancelled, don't perform the wrapping.
+ */
+public class ScreenWrapEvent extends Event {
+
+    public Entity entity;
+
+    public ScreenWrapEvent(Entity entity) {
+        this.entity = entity;
+    }
+
+}

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

@@ -8,10 +8,12 @@ import com.me.asteroids.Constants;
 import com.me.asteroids.EntityFactory;
 import com.me.asteroids.Graphics;
 import com.me.asteroids.components.AccelerationComponent;
+import com.me.asteroids.components.BulletComponent;
 import com.me.asteroids.components.ModelComponent;
 import com.me.asteroids.components.PlayerComponent;
 import com.me.asteroids.components.PositionComponent;
 import com.me.asteroids.components.VelocityComponent;
+import com.me.asteroids.events.ScreenWrapEvent;
 import com.me.asteroids.systems.CollisionSystem;
 import com.me.asteroids.systems.ModelRenderSystem;
 import com.me.asteroids.systems.MovementSystem;
@@ -20,8 +22,10 @@ import com.me.asteroids.systems.ScreenWrapSystem;
 import com.me.common.Screen;
 import com.me.common.ecs.Engine;
 import com.me.common.ecs.Entity;
+import com.me.common.ecs.event.EventHandler;
+import com.me.common.ecs.event.Listener;
 
-public class GameScreen extends Screen {
+public class GameScreen extends Screen implements Listener {
 
     Engine engine;
 
@@ -43,6 +47,7 @@ public class GameScreen extends Screen {
         engine = new Engine();
 
         engine.registerComponentClass(PlayerComponent.class);
+        engine.registerComponentClass(BulletComponent.class);
         engine.registerComponentClass(PositionComponent.class);
         engine.registerComponentClass(VelocityComponent.class);
         engine.registerComponentClass(AccelerationComponent.class);
@@ -54,6 +59,8 @@ public class GameScreen extends Screen {
         engine.registerSystem(new ScreenWrapSystem(engine));
         engine.registerSystem(new ModelRenderSystem(engine, graphics));
 
+        engine.registerListener(this);
+
         engine.ready();
 
         Entity player = EntityFactory.createPlayer(engine);
@@ -77,4 +84,14 @@ public class GameScreen extends Screen {
 
     }
 
+    @EventHandler
+    public void onScreenWrap(ScreenWrapEvent event) {
+        if (event.entity.hasComponent(BulletComponent.class)) {
+            // Remove bullets when they leave the screen
+            event.setCancelled(true);
+            event.entity.remove();
+        }
+    }
+
+
 }

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

@@ -5,6 +5,7 @@ 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.asteroids.events.ScreenWrapEvent;
 import com.me.common.ecs.ComponentMapper;
 import com.me.common.ecs.Engine;
 import com.me.common.ecs.Entity;
@@ -21,6 +22,15 @@ public class ScreenWrapSystem extends EntitySystem {
         modelMapper = engine.getComponentMapper(ModelComponent.class);
     }
 
+    private void updatePosition(Entity entity, Vector2 position, float newX, float newY) {
+        ScreenWrapEvent event = new ScreenWrapEvent(entity);
+        engine.callEvent(event);
+        if (!event.isCancelled()) {
+            position.set(newX, newY);
+        }
+    }
+
+
     @Override
     public void processEntity(Entity entity, float dt) {
         PositionComponent positionComponent = positionMapper.get(entity);
@@ -33,10 +43,10 @@ public class ScreenWrapSystem extends EntitySystem {
         float minY = aabb.y;
         float maxY = minY + aabb.height;
         if (minY > Constants.HEIGHT) {
-            position.y = (position.y - maxY) + (minY - Constants.HEIGHT);
+            updatePosition(entity, position, position.x, (position.y - maxY) + (minY - Constants.HEIGHT));
             return;
         } else if (maxY < 0) {
-            position.y = Constants.HEIGHT + (position.y - minY) + maxY;
+            updatePosition(entity, position, position.x, Constants.HEIGHT + (position.y - minY) + maxY);
             return;
         }
 
@@ -44,9 +54,9 @@ public class ScreenWrapSystem extends EntitySystem {
         float minX = aabb.x;
         float maxX = minX + aabb.width;
         if (maxX < 0) {
-            position.x = Constants.WIDTH + (position.x - minX) + maxX;
+            updatePosition(entity, position, Constants.WIDTH + (position.x - minX) + maxX, position.y);
         }  else if (minX > Constants.WIDTH) {
-            position.x = (position.x - maxX) + (minX - Constants.WIDTH);
+            updatePosition(entity, position, (position.x - maxX) + (minX - Constants.WIDTH), position.y);
 
         }
     }