Chapter 4: Images and sound

After Chapter 1 you have a player that moves. This chapter is how you give it a picture and a sound without stalling the game loop.

Where files go

ActiverseImage and ActiverseSound both go through ResourcePaths: an existing file on disk first, then a classpath resource (so a packaged jar still works). Use a relative path and keep the same folder layout in your IDE and in the jar.

your-project/
  Main.java
  MyWorld.java
  Player.java
  assets/
    images/
      player.png
      world.png
      coin.png
    sounds/
      pickup.wav

Load with paths like "assets/images/player.png". Putting files next to your .java sources also works if that is the working directory; a dedicated assets folder is easier to keep straight.

Images

Supported types include png, jpg, gif, and bmp. Size the file to the actor (a 32×32 character should use a 32×32 image). Set it once in the constructor, not every tick:

public Player() {
    setImage(new ActiverseImage("assets/images/player.png"));
}

Worlds use setBackgroundImage("assets/images/world.png"). Backgrounds are optional; without one you get the panel’s default fill.

Do not call setImage every act() unless you are actually changing frames. Reloading the same file sixty times a second will hitch.

Sound

ActiverseSound loads WAV files. Construct the clip once, register it on the world with addSound (so debug and shutdown can see it), then play from a condition — never from the top of act() with no guard.

import ActiverseEngine.*;

public class Player extends Actor {
    private ActiverseSound pickup;

    public Player() {
        setImage(new ActiverseImage("assets/images/player.png"));
    }

    public void setPickupSound(ActiverseSound sound) {
        pickup = sound;
    }

    public void playPickup() {
        if (pickup != null && !pickup.isPlaying()) {
            pickup.play();
        }
    }

    @Override
    public void act() {
        if (KeyboardInfo.isLetterDown('w')) {
            move(5);
        }
    }
}

public class MyWorld extends World {
    public MyWorld() {
        super(400, 400, 1);
        setBackgroundImage("assets/images/world.png");

        Player player = new Player();
        addObject(player, 100, 100);

        ActiverseSound pickup = new ActiverseSound("assets/sounds/pickup.wav");
        addSound(pickup);
        player.setPickupSound(pickup);
    }
}

Useful methods: play(), stop(), loop(), loop(int count), pause() / resume(), setVolume(float) (0 to 1), isPlaying(). Check isPlaying() (or a key edge with KeyboardInfo.justPressed) so a held key does not restart the clip every tick.

Optional: mouse

Keyboard movement from Chapter 1 is enough for a first game. If you want clicks, call ActiverseMouseInfo.createInstance(this) in the world constructor (the world is a panel), then poll isLeftClick() / isRightClick() and getMouseLocationOnComponent() from act().

Next: Chapter 5 — other actors and collision.