Develop Reference

libgdx inputListener doesn't work with actor

I tried use InputListener with Actor, but it doesn't work. I really don't know why. I found many information about it and saw official documentation but not one of all didn't help me.
My log messages are not shown when I touch the sprite. But if I use the global input processor (for whole screen) it works fine, but I want to add only one listener only for actor.
What am I doing wrong?
public class GameScreen implements Screen {
final Launch launch;
Texture texture;
Stage stage;
public GameScreen(Launch launch) {
Gdx.app.setLogLevel(Application.LOG_DEBUG);
this.launch = launch;
texture = new Texture("hero.png");
stage = new Stage();
Hero hero = new Hero();
hero.addListener(new HeroListener());
stage.addActor(hero);
Gdx.input.setInputProcessor(stage);
}
#Override
public void render(float delta) {
Gdx.gl.glClearColor(0, 0, 0.2f, 1);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
stage.draw();
stage.act(Gdx.graphics.getDeltaTime());
}
#Override
public void resize(int width, int height) {
}
#Override
public void show() {
}
#Override
public void hide() {
}
#Override
public void pause() {
}
#Override
public void resume() {
}
#Override
public void dispose() {
stage.dispose();
texture.dispose();
}
private class Hero extends Actor {
#Override
public boolean addListener(EventListener listener) {
Gdx.app.debug("MyTag", "my debug message");
return super.addListener(listener);
}
#Override
public void draw(Batch batch, float parentAlpha) {
batch.draw(texture, 0, 0, 500, 500);
}
}
private class HeroListener extends InputListener {
#Override
public boolean touchDown(InputEvent event, float x, float y, int pointer, int button) {
Gdx.app.debug("MyTag", "touch down");
return super.touchDown(event, x, y, pointer, button);
}
#Override
public void touchUp(InputEvent event, float x, float y, int pointer, int button) {
Gdx.app.debug("MyTag", "touch up");
super.touchUp(event, x, y, pointer, button);
}
}
}

The problem is that you are not giving any size or position to your actor. InputListener work for events whitin the bounds of the Actor. If you do not define any size to your Actor, it won't ever receive an event.
Hero hero = new Hero();
hero.addListener(new HeroListener());
hero.setBounds(0, 0, 500, 500);
stage.addActor(hero);
That should make your InputListener listen to touchDown/Up events in the (0, 0), (500, 500) bounds.
Also, it's conveninent because you can use those bounds when drawing after:
#Override
public void draw(Batch batch, float parentAlpha) {
batch.draw(texture, getX(), getY(), getWidth(), getHeight());
}

Rotation of sprite, libgdx android

I want my sprite which is a basketball to rotate. How can i make my sprite to rotate counter-clockwise based on delta time? Do you have a calculation for it?

call rotateSprite() method whenever you want to rotate your ball.
Take a look of my Test code.
public class TestGame extends Game {
SpriteBatch spriteBatch;
Sprite ball;
Texture ballTex;
private int spriteRotationSpeed=1;
#Override
public void create() {
spriteBatch=new SpriteBatch();
ballTex=new Texture("image/bone.png");
ball=new Sprite(ballTex);
ball.setSize(50,50);
ball.setOrigin(25,25);
ball.setPosition(0,0);
}
#Override
public void render() {
super.render();
Gdx.gl.glClearColor(1,1,1,1);
gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
spriteBatch.begin();
ball.draw(spriteBatch);
spriteBatch.end();
rotateSprite();
}
private void rotateSprite(){
float rotation=ball.getRotation();
rotation+=spriteRotationSpeed;
if(rotation>360)
rotation-=360;
ball.setRotation(rotation);
}
#Override
public void resize(int width, int height) {
super.resize(width, height);
}
#Override
public void dispose() {
super.dispose();
ballTex.dispose();
spriteBatch.dispose();
}
}

Stop Camera from moving

I've been trying to stop moving my camera at the end of my map, but it continues to move.
Here is my code:
#Override
public void render(float delta) {
//moving tiled map
camera.position.x=camera.position.x+Gdx.graphics.getDeltaTime()*200;
camera.update();
//...........................................
Gdx.gl.glClearColor(1, 0, 0, 0);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
// renderer camera and map
renderer.setView(camera);
renderer.render();
//...................................................
}
#Override
public void show() {
batch = new SpriteBatch();
map = new TmxMapLoader().load("maps/map1.tmx");
renderer = new OrthogonalTiledMapRenderer(map);
camera = new OrthographicCamera();
}
#Override
public void hide() {
}
#Override
public void create() {
}
#Override
public void resize(int width, int height) {
camera.viewportWidth = width;
camera.viewportHeight = height;
camera.position.set(width/2f, height/3f, 0); //by default camera position on (0,0,0)
camera.update();
}
#Override
public void render() {
}
#Override
public void pause() {
}
#Override
public void resume() {
}
#Override
public void dispose() {
map.dispose();
renderer.dispose();
}
}
I couldn't find any error in my code.
So my question here is, how to stop the camera from moving at the end of the map?

You have at least one layer in the tiled map, so:
TiledMap map = ......//whatever method that you are using to load a map
//skip to the part that the map is loaded
TiledMapLayer layer = (TiledMapLayer)map.getLayers().get(0);
int layerWidth = layer.getWidth()*layer.getTileWidth();
And now, you know the layer's width in pixels, and yo can make sure that camera.position.x+Gdx.graphics.getDeltaTime()*200; never exceeds this length.

LibGDX - how do I make my menu screen switch to the Game screen?

When I run the application my menu screen shows, but when I click the screen to begin playing the game the game begins playing but the menu screen is still their overlaying the game. I know this because the game has music playing. I'm also going to add a splash screen in the future but I'm not concerned about that right now. I'm new at this so please explain things as best as you can. Below are the 3 classes used to make this happen.
public class SlingshotSteve extends Game {
public SpriteBatch batch;
public BitmapFont font;
public void create() {
batch = new SpriteBatch();
//Use LibGDX's default Arial font.
font = new BitmapFont();
this.setScreen(new Menu(this));
}
public void render() {
super.render(); //important!
}
public void dispose() {
batch.dispose();
font.dispose();
}
}
Here is the main menu screen
public class Menu implements Screen {
final SlingshotSteve game;
OrthographicCamera camera;
public Menu(final SlingshotSteve gam) {
game = gam;
camera = new OrthographicCamera();
camera.setToOrtho(false, 800, 480);
}
#Override
public void render(float delta) {
Gdx.gl.glClearColor(0, 0, 0.2f, 1);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
camera.update();
game.batch.setProjectionMatrix(camera.combined);
game.batch.begin();
game.font.draw(game.batch, "Welcome to Slingshot Steve!!! ", 100, 150);
game.font.draw(game.batch, "Tap anywhere to begin!", 100, 100);
game.batch.end();
if (Gdx.input.isTouched()) {
game.setScreen((Screen) new GameScreen(game));
dispose();
}
}
Here is the game screen
public class GameScreen implements Screen {
final SlingshotSteve game;
OrthographicCamera camera;
// Creates our 2D images
SpriteBatch batch;
TextureRegion backgroundTexture;
Texture texture;
GameScreen(final SlingshotSteve gam) {
this.game = gam;
camera = new OrthographicCamera(1280, 720);
batch = new SpriteBatch();
Texture texture = new Texture(Gdx.files.internal("background.jpg"));
backgroundTexture = new TextureRegion(texture, 0, 0, 500, 500);
Music mp3Sound = Gdx.audio.newMusic(Gdx.files.internal("rain.mp3"));
mp3Sound.setLooping(true);
mp3Sound.play();
}
public void render() {
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
camera.update();
batch.setProjectionMatrix(camera.combined);
batch.begin();
batch.draw(backgroundTexture, 0, 0);
batch.end();
}
#Override
public void resize(int width, int height) {
}
#Override
public void pause() {
}
#Override
public void resume() {
}
#Override
public void dispose() {
batch.dispose();
texture.dispose();
}

In addition to Phonbopit's answer. You should probably #Override the render function at GameScreen.

Not sure but I think your render() method on GameScreen not called. you must implement method render(float delta) that use delta time for parameter.
replace
public void render() {
// your code
}
with
public void render(float delta) {
// your code
}

How we can remove the back texture in libGDX?

private Texture druidTexture;
private SpriteBatch batch;
Sprite sprite;
#Override
public void create() {
druidTexture = new Texture(Gdx.files.internal("star-large.gif"));
sprite = new Sprite(druidTexture);
batch = new SpriteBatch();
}
#Override
public void dispose() {
}
#Override
public void pause() {
}
#Override
public void render() {
batch.begin();
sprite.rotate(45);
float x=sprite.getX();
float y=sprite.getY();
float newx=x+1;
System.out.println(newx);
float newy=y+1;
sprite.setX(newx);
sprite.draw(batch);
batch.end();
}
#Override
public void resize(int arg0, int arg1) {
}
#Override
public void resume() {
}
}
i am getting output for the above code as this
but i need to remove the star at back,for each star,how can i do that??

You need to clear the screen before each frame as described here:
public void render () {
Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT); // This cryptic line clears the screen.
batch.begin();
// Drawing goes here!
batch.end();
}

Clear the screen firstly in function render
#Override
public void render() {
Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
.....
}