Chunk targets

Each chunk has some content, like entities (e.g. player, opponents, obstacles). Therefore a chunk needs to know, what he has to save. For that purpose, chunx provides an interface, called ChunkTarget. By implementing the interface, you're able to add your entities to a chunk system.

Here is an example of a simple spaceship class which implements the interface:

public class Spaceship implements ChunkTarget {

   private float x, y;

   public Spaceship(float x, float y) {
      this.x = x;
      this.y = y;
   }

   @Override
   public float getX() {
      return x;
   }

   @Override
   public float getY() {
      return y;
   }

   @Override
   public void setX(float x) {
      this.x = x;
   }

   @Override
   public void setY(float y) {
      this.y = y;
   }
}

You learn how to use the target in the next tutorial about content providers.

Moveable targets

It is quite often the case that your game contains moveable patys like bullets or, spaceships. Moveable elements are handled much differently as regular targets. Therefore you need to implement another interface, called MoveableChunkTarget.

A basic implementation would look like this:

public class Spaceship implements MoveableChunkTarget {

   private float x, y;

   // This one is needed to detect movement
   private MovementDetector movementDetector;

   public Spaceship(float x, float y) {
      this.x = x;
      this.y = y;
      // Don't initialize it here, this is the constructor! (dangerous)
      //movementDetector = new SimpleMovementDetector(this);
   }

   @Override
   public float getX() {
      return x;
   }

   @Override
   public float getY() {
      return y;
   }

   @Override
   public void setX(float x) {
      this.x = x;
   }

   @Override
   public void setY(float y) {
      this.y = y;
   }

   @Override
   public void update() {
      // Update the tracker, so chunx can detect movement
      movementDetector.update();
   }

   @Override
   public MovementDetector getMovementDetector() {

      if (movementDetector == null) {
         movementDetector = new SimpleMovementDetector(this);
      }

      return movementDetector;
   }

   @Override
   public void setMovementDetector(MovementDetector detector) {
      this.movementTracker = detector;
   }
}