libGDX: Scene2D
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The document discusses LibGDX's support for internationalization and scene 2D. It describes how to create property files for different languages to support internationalization in LibGDX games. It then provides an overview of Scene2D, describing it as an optional higher-level framework for creating 2D games and UIs using stages, actors, and events. It includes code examples of creating a stage and adding an actor, as well as handling input events with actors.
libGDX: Scene2D
- 1. LibGDX: Internaliza1on and Scene 2D Jussi Pohjolainen Tampere University of Applied Sciences
- 3. Support for Mul1ple Languages • Create defaults proper1es file: – MyBundle.properties • Create other language files: – MyBundle.fi_FI.properties
- 4. MyBundle.proper1es title=My Game score=You score {0}
- 6. In Java Locale locale = new Locale("fi"); I18NBundle myBundle = I18NBundle.createBundle(Gdx.files.internal("MyBundle"), locale); String title = myBundle.get("title"); String score = myBundle.get("score", 50);
- 7. Notes • If you don't specify locale, default locale is used • Charset is UTF-‐8 (without BOM) • See: – hVps://github.com/libgdx/libgdx/wiki/ Interna1onaliza1on-‐and-‐Localiza1on
- 8. SCENE2D
- 9. Scene2D? • It’s op1onal, you don’t need it. But you may want to use it. • May be useful for "board games" • Higher level framework for crea>ng games • Provides UI Toolkit also: Scene2d.ui • Tutorial – https://github.com/libgdx/libgdx/wiki/Scene2d
- 10. Concepts • Stage – “Screens”, “Stages”, “Levels” – Camera watching the stage – Contains group of actors • Actors – “Sprites”
- 11. Roughly the Idea in Code Stage gameStage = new Stage(); // PlayerActor extends Actor { .. } PlayerActor player = new PlayerActor(); // Let's add the actor to the stage gameStage.addActor(player);
- 12. Possibili1es • Event system for actors; when actor is touched, dragged .. – Hit detec>on; dragging / touching within the bounds of actor • Ac>on system: rotate, move, scale actors in parallel – Also rota1on and scaling of group of actors
- 13. Stage • Stage implements InputProcessor, so it can directly input events from keyboard and touch • Add to your Applica1onAdapter – Gdx.input.setInputProcessor(myStage); • Stage distributes input to actors • Use setViewport to set the camera – myStage.setViewPort(...); • Stage has act method, by calling this, every act method of every actor is called
- 14. Actors • Actor has an posi1on, rect size, scale, rota1on… • Posi1on is the leb corner of the actor • Posi1on is rela1ve to the actor’s parent • Actor may have ac>ons – Change the presenta>on of the actor (move, resize) • Actor can react to events
- 15. public class StageGame extends ApplicationAdapter { // Stage contains hierarcy of actors private Stage stage; // We will have player actor in the stage private BlueBirdActor playerActor; @Override public void create () { // Creating the stage stage = new Stage(); // Creating the actors playerActor = new BlueBirdActor(); // add actors to stage stage.addActor(playerActor); } @Override public void render () { Gdx.gl.glClearColor(1, 0, 0, 1); Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT); // Call act on every actor stage.act(Gdx.graphics.getDeltaTime()); // Call draw on every actor stage.draw(); } }
- 16. public class BlueBirdActor extends Actor { private Texture texture; public BlueBirdActor() { texture = new Texture(Gdx.files.internal("blue-bird-icon.png")); } @Override public void draw(Batch batch, float alpha) { batch.draw(texture, getX(), getY()); } @Override public void act(float delta) { super.act(delta); } }
- 17. Event System • Stage will be responsible for gedng user input – Gdx.input.setInputProcessor(stage); • Stage will fire events to actors • Actor may receive events if it has a listener – actor.addListener(new InputListener() { … } ); • Actor must specify bounds in order to receive input events within those bounds! • To handle key input, actor has to have keyboard focus
- 18. public class StageGame extends ApplicationAdapter { // Stage contains hierarcy of actors private Stage stage; // We will have player actor in the stage private BlueBirdActor playerActor; @Override public void create () { // Creating the stage stage = new Stage(); // Sets the InputProcessor that will receive all touch and key input events. // It will be called before the ApplicationListener.render() method each frame. // // Stage handles the calling the inputlisteners for each actor. Gdx.input.setInputProcessor(stage); // Creating the actors playerActor = new BlueBirdActor(); // add actors to stage stage.addActor(playerActor); stage.setKeyboardFocus(playerActor); } @Override public void render () { Gdx.gl.glClearColor(1, 0, 0, 1); Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT); // Call act on every actor stage.act(Gdx.graphics.getDeltaTime()); // Call draw on every actor stage.draw(); } }
- 19. public class BlueBirdActor extends Actor { private boolean up, down, left, right public BlueBirdActor() { addListener(new PlayerListener()); } @Override public void act(float delta) { if(up) { setY(getY() + speed * delta); } } // InputListener implements EventListener, just override the methods you need // Also ActorGestureListener available: fling, pan, zoom, pinch.. class PlayerListener extends InputListener { @Override public boolean keyDown(InputEvent event, int keycode) { if(keycode == Input.Keys.UP) { up = true; } return true; } @Override public boolean keyUp(InputEvent event, int keycode) { if(keycode == Input.Keys.UP) { up = false; } return true; } } }
- 20. Ac1ons • Each actor has a list of ac1ons • Updated on every frame (act-‐method) • Many ac1ons available – MoveToAction – RotateToAction – ScaleToAction • Example – MoveToAction action = new MoveToAction(); – action.setPosition(300f, 700f); – action.setDuration(2f); – actor.addAction(action);
- 21. Grouping Ac1ons in Sequence SequenceAction sequenceAction = new SequenceAction(); MoveToAction moveAction = new MoveToAction(); RotateToAction rotateAction = new RotateToAction(); ScaleToAction scaleAction = new ScaleToAction(); moveAction.setPosition(200f, 400f); moveAction.setDuration(1f); rotateAction.setRotation(rotate); rotateAction.setDuration(1f); scaleAction.setScale(0.5f); scaleAction.setDuration(1f); sequenceAction.addAction(moveAction); sequenceAction.addAction(rotateAction); sequenceAction.addAction(scaleAction); actor.addAction(sequenceAction);
- 22. Grouping Ac1ons in Parallel ParallelAction parallel = new ParallelAction (); MoveToAction moveAction = new MoveToAction(); RotateToAction rotateAction = new RotateToAction(); ScaleToAction scaleAction = new ScaleToAction(); moveAction.setPosition(200f, 400f); moveAction.setDuration(1f); rotateAction.setRotation(rotate); rotateAction.setDuration(1f); scaleAction.setScale(0.5f); scaleAction.setDuration(1f); parallel.addAction(moveAction); parallel.addAction(rotateAction); parallel.addAction(scaleAction); actor.addAction(parallel);
- 23. Ac1ons Complete? SequenceAction sequenceAction = new SequenceAction(); ParallelAction parallelAction = new ParallelAction(); MoveToAction moveAction = new MoveToAction(); RotateToAction rotateAction = new RotateToAction(); RunnableAction runnableAction = new RunnableAction(); moveAction.setPosition(200f, 400f); moveAction.setDuration(1f); moveAction.setInterpolation(Interpolation.bounceOut); rotateAction.setRotation(rotate); rotateAction.setDuration(1f); runnableAction.setRunnable(new Runnable() { public void run() { System.out.println("done!"); } }); parallelAction.addAction(rotateAction); parallelAction.addAction(moveAction); sequenceAction.addAction(parallelAction); sequenceAction.addAction(runnableAction);
- 24. Enable rotate and scale in drawing @Override public void draw(Batch batch, float alpha){ batch.draw(texture, this.getX(), this.getY(), this.getOriginX(), this.getOriginY(), this.getWidth(), this.getHeight(), this.getScaleX(), this.getScaleY(), this.getRotation(),0,0, texture.getWidth(), texture.getHeight(), false, false); }
- 25. Grouping Group group = new Group(); group.addActor(playerActor); group.addActor(monsterActor); group.addAction( ... ); stage.addActor(group);
- 27. Scene2D.UI • Tutorial – hVps://github.com/libgdx/libgdx/wiki/Scene2d.ui • To quickly get started, add following to your project – uiskin.png, uiskin.atlas, uiskin.json, default.fnt – hVps://github.com/libgdx/libgdx/tree/master/ tests/gdx-‐tests-‐android/assets/data • Tutorial and examples – hVps://github.com/libgdx/libgdx/wiki/Scene2d.ui
- 28. TextBuVon example Skin skin = new Skin( Gdx.files.internal("uiskin.json") ); final TextButton button = new TextButton("Hello", skin); button.setWidth(200f); button.setHeight(20f); button.setPosition(Gdx.graphics.getWidth() /2 - 100f, Gdx.graphics.getHeight()/2 - 10f); startStage.addActor(button); Gdx.input.setInputProcessor(startStage); button.addListener(new ClickListener(){ @Override public void clicked(InputEvent event, float x, float y){ whichScreen = !whichScreen; Gdx.input.setInputProcessor(gameStage); } });