Add DecayComponent and DecaySystem

Add DecayComponent to debris entities so they disappear after while.

decayTimer set to a random value between 0.5 and 2.5 seconds.

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

@@ -8,6 +8,7 @@ import com.me.asteroids.components.AsteroidComponent;
 import com.me.asteroids.components.BulletComponent;
 import com.me.asteroids.components.ColliderComponent;
 import com.me.asteroids.components.DebrisComponent;
+import com.me.asteroids.components.DecayComponent;
 import com.me.asteroids.components.ModelComponent;
 import com.me.asteroids.components.PlayerComponent;
 import com.me.asteroids.components.PositionComponent;
@@ -129,6 +130,7 @@ public class EntityFactory {
             debris.addComponent(position);
             debris.addComponent(velocity);
             debris.addComponent(model);
+            debris.addComponent(new DecayComponent(rand.nextFloat(0.5f, 2.5f)));
             debris.addComponent(new DebrisComponent());
             entities[i] = debris;
         }

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

@@ -0,0 +1,19 @@
+package com.me.asteroids.components;
+
+import com.me.common.ecs.Component;
+
+public class DecayComponent implements Component {
+
+    public float decayTimer;
+    public boolean remove;
+
+    public DecayComponent(float decayTimer) {
+        this(decayTimer, true);
+    }
+
+    public DecayComponent(float decayTimer, boolean remove) {
+        this.decayTimer = decayTimer;
+        this.remove = remove;
+    }
+
+}

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

@@ -13,6 +13,7 @@ import com.me.asteroids.components.AsteroidComponent;
 import com.me.asteroids.components.BulletComponent;
 import com.me.asteroids.components.ColliderComponent;
 import com.me.asteroids.components.DebrisComponent;
+import com.me.asteroids.components.DecayComponent;
 import com.me.asteroids.components.ModelComponent;
 import com.me.asteroids.components.PlayerComponent;
 import com.me.asteroids.components.PositionComponent;
@@ -23,6 +24,7 @@ import com.me.asteroids.events.PlayerASteroidCollisionEvent;
 import com.me.asteroids.events.ScreenWrapEvent;
 import com.me.asteroids.systems.AsteroidSpawningSystem;
 import com.me.asteroids.systems.CollisionSystem;
+import com.me.asteroids.systems.DecaySystem;
 import com.me.asteroids.systems.ModelRenderSystem;
 import com.me.asteroids.systems.MovementSystem;
 import com.me.asteroids.systems.PlayerInputSystem;
@@ -59,6 +61,7 @@ public class GameScreen extends Screen implements Listener {
         engine.registerComponentClass(BulletComponent.class);
         engine.registerComponentClass(AsteroidComponent.class);
         engine.registerComponentClass(DebrisComponent.class);
+        engine.registerComponentClass(DecayComponent.class);
         engine.registerComponentClass(ColliderComponent.class);
         engine.registerComponentClass(PositionComponent.class);
         engine.registerComponentClass(VelocityComponent.class);
@@ -67,6 +70,7 @@ public class GameScreen extends Screen implements Listener {
 
         engine.registerSystem(new PlayerInputSystem(engine));
         engine.registerSystem(new AsteroidSpawningSystem(engine));
+        engine.registerSystem(new DecaySystem(engine));
         engine.registerSystem(new MovementSystem(engine));
         engine.registerSystem(new CollisionSystem(engine));
         engine.registerSystem(new ScreenWrapSystem(engine));

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

@@ -0,0 +1,31 @@
+package com.me.asteroids.systems;
+
+import com.me.asteroids.components.DecayComponent;
+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 DecaySystem extends EntitySystem {
+
+    private ComponentMapper<DecayComponent> decayTimerMapper;
+
+    public DecaySystem(Engine engine) {
+        super(engine, DecayComponent.class);
+        decayTimerMapper = engine.getComponentMapper(DecayComponent.class);
+    }
+
+    @Override
+    public void processEntity(Entity entity, float dt) {
+        DecayComponent decayComponent = decayTimerMapper.get(entity);
+        if ((decayComponent.decayTimer -= dt) <= 0) {
+            if (decayComponent.remove) {
+                entity.remove();
+            } else {
+                entity.deactivate();
+            }
+
+        }
+    }
+
+}