Library which provides parallax scrolling support for Java 2D libraries such as LibGDX and Slick2D.

Features

This library is able to..

• generate custom (pre-processed) textures on runtime
• display parallax effects
• customize your backgrounds with parallax patterns

#Download

You can download the library here.

Getting started

To create a new parallax effect, you need a so called Viewport and ParallaxMapper. The Viewport is an required interface implementation of your field of view (FOV). You can implement for instance the interface in your camera class:

public class MyCamera extends Camera implements Viewport {

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

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

   @Override
   public float getRight() {
      return getLeft() + getWidth();
   }

   @Override
   public float getBottom() {
      return getTop() + getHeight();
   }
}

Afterwards you are able to create your parallax mapper:

MyCamera camera = new MyCamera();
ParallaxMapper mapper = new ParallaxMapper(camera);

Slick2D remarks

The parallax system works only with matrix translation. Therefore you need to translate the matrix by the current camera position:

// Code in the render method
g.pushMatrix();
g.translate(camera.getX(), camera.getY();
mapper.render();
g.popMatrix();

LibGDX remarks

In order to use the parallax effect properly, you have to define a SpriteBatch instance. You need to wrap begin and end around the render method:

batch.begin();
mapper.render();
batch.end();

Adding layers

To add a layer, you need a layer configuration. This configuration requires a LayerTexture in order to draw the parallax effect properly. For LibGDX and Slick2D exist already implementation of those textures.

Image image = new Image("test.png"); // Slick2D
LayerTexture texture = new SlickTexture(image); // Slick2D
LayerConfig config = new LayerConfig(texture);
mapper.add(10.0f, config);

That's all! You can define a so called z index in order to specify the distance of the layer.

Preprocessed Textures

It is also possible to create textures on your own on runtime! For instance you want to generate some kind of random star field without using a pre-defined image texture. You need to implement TextureProcessor due to generate a texture on your own:

TexturePreprocessor processor = new SlickTextureProcessor({

   @Override
   public void process(Graphics g) {
      g.setColor(Color.red);
      g.fillRect(0, 0, 10, 10);
   }
});

LayerTexture customTexture = new PreprocessedTexture(64, 64, processor);
config.setTexture(customTexture);
mapper.add(20.0f, config); 

As you can see it is pretty easy to extend your parallax effect by custom textures.