Parallax scrolling is a special scrolling technique that creates the illusion of depth in a 2D scene. Therefore, the objects in the background move slower than the objects in the foreground when the camera moves by.

We will now implement a parallax scrolling effect for the mountains in the background of the game screen.

Add the following import line to the Mountains class:

import com.badlogic.gdx.math.Vector2;

After this, add the following lines of code to the same class:

public void updateScrollPosition (Vector2 camPosition) {
position.set(camPosition.x, position.y);
}

Next, make the following changes to the same class:

private void drawMountain (SpriteBatch batch, float offsetX, float offsetY, float tintColor, float parallaxSpeedX) {
TextureRegion reg = null;
batch.setColor(tintColor, tintColor, tintColor, 1);
floatxRel = dimension.x * offsetX;
floatyRel = dimension.y * offsetY;

  // mountains span the whole level  
int mountainLength...