We Keep Coding

libgdx set position of enemy/monster on the map not in camera view

I'm struggling to set up monster on the map, but all I get is placing it on the camera coordinate. I tried to use Tiled and finally I set up monster where I wanted, but I don't know how to move this monster.
Link to game map, the dragon in right bottom corner is from Enemy class, and the goblin is from Bot class
Here same code from Enemy class
public Enemy() {
img = new Texture(Gdx.files.internal(path));
sprite = new Sprite(img);
batch = new SpriteBatch();
position = new Vector2();
}
public void update(float delta) {
batch.begin();
batch.draw(img, position.x, position.y);
batch.end();
}
And the Bot class, where I get monster from Tiled
public Bot(TextureMapObjectRenderer tiledMapRenderer, String name) {
this.tiledMapRenderer = tiledMapRenderer;
try {
monsterLayer = tiledMapRenderer.getMap().getLayers().get("monster");
monsterObjects = monsterLayer.getObjects();
monster = monsterObjects.get(name);
} catch (Exception ex) {
}
}
public void update(float delta) {
tiledMapRenderer.renderObject(monster);
}

I use TextureMapObject to get X and Y position of the enemy/monster. Also I create method to render MapObject.
public void renderMonster(MapObject object) {
if (object instanceof TextureMapObject) {
TextureMapObject textureMonster = (TextureMapObject) object;
textureMonsters.add(textureMonster);
batch.begin();
batch.draw(textureMonster.getTextureRegion(), textureMonster.getX(), textureMonster.getY());
batch.end();
// move the monster
textureMonster.setX(randomMove(-1, 1).x + textureMonster.getX());
textureMonster.setY(randomMove(-1, 1).y + textureMonster.getY());
}
}
I know that this method is not prefect, but it works.

LibGDX - How to spawn objects at a certain distance from each other?

So I'm trying to create a game and it's my first time. My game is a 2D side scroller and is about the player in space avoiding the incoming meteors. I have successfully managed to get the meteors spawning randomly on the x and y axis off screen and re position once it has gone pass the screen.
But the problem I face now is sometimes the spawn of the meteors will clump together which I don't want. How do I get the meteors to spawn at a certain distance from each other so they don't clump together. I couldn't find any good tutorials or if anyone can point me to the right direction. Below are my codes so far.
Meteor Class
public class Meteors {
private Texture bigMeteor;
private Vector2 posBigMeteor;
private Random yrand;
//Constructor
public Meteors(float x){
bigMeteor = new Texture("meteor.png");
yrand = new Random();
//Spawn location of meteor
posBigMeteor = new Vector2(x, yrand.nextInt(AstroDemo.HEIGHT/2 - bigMeteor.getHeight()));
}
public Texture getBigMeteor() {
return bigMeteor;
}
public Vector2 getPosBigMeteor() {
return posBigMeteor;
}
//Reposition the meteors
public void reposition(float x){
posBigMeteor.set(x, yrand.nextInt(AstroDemo.HEIGHT/2 - bigMeteor.getHeight()));
}
}
PlayState Class
public class PlayState extends State {
//Total meteor count on screen
private static final int METEOR_COUNT = 8;
private Naught naught;
private Texture bg;
private Random xrand;
private Array <Meteors> meteors;
public PlayState(GameStateManager gsm) {
super(gsm);
//Starting co-ordinates of main character (Naught)
naught = new Naught(50, 100);
//Setting viewport of the camera
cam.setToOrtho(false, AstroDemo.WIDTH/2, AstroDemo.HEIGHT/2);
bg = new Texture("bg.png");
xrand = new Random();
meteors = new Array <Meteors>();
//Spawn meteors randomly off screen
for (int i = 1; i <= METEOR_COUNT; i++){
meteors.add(new Meteors(AstroDemo.WIDTH/2 + (xrand.nextInt(300))));
}
}
#Override
protected void handleInput() {
//If screen/mouse is held
if(Gdx.input.isTouched()){
//Main Character jumps/flys
naught.jump();
}
}
#Override
public void update(float dt) {
handleInput();
naught.update(dt);
//If meteors are left side of the screen, re-position to the right side of the screen
for(Meteors meteor : meteors){
if (cam.position.x - (cam.viewportWidth/2) > meteor.getPosBigMeteor().x + meteor.getBigMeteor().getWidth()){
meteor.reposition(meteor.getPosBigMeteor().x + (AstroDemo.WIDTH/2 + 20 + (xrand.nextInt(300))));
}
}
cam.position.x = naught.getPosition().x + 80;
cam.update();
}
#Override
public void render(SpriteBatch sb) {
//Adjust the spritebatch for co-ordinate system in relation to camera
sb.setProjectionMatrix(cam.combined);
sb.begin();
//Draw background where the camera is
sb.draw(bg, cam.position.x - (cam.viewportWidth/2), 0);
sb.draw(naught.getTexture(), naught.getPosition().x, naught.getPosition().y);
for (Meteors meteor : meteors) {
sb.draw(meteor.getBigMeteor(), meteor.getPosBigMeteor().x, meteor.getPosBigMeteor().y);
}
sb.end();
}
#Override
public void dispose() {
}
}

create a array of predefined value for your y position and then get value randomly from that array.
or
Divide height into sub portion then get random value from that portion so that each random value not collide with other value.

How to scroll a ScrollPane in code?

I’m trying to make a scrollwheel component like this in LibGDX:
I’m using ScrollPane since it has input and fling handling built in. I have an image for the scrollwheel that is divided into 14 sections, the scrollpane itself is two sections shorter so that there will be one section on the right and left sides that it can scroll to in either direction. Once the scroll position reaches the end in either direction I want to reset the scroll position back to the center. Doing this over and over again should create the illusion of an infinite scrolling wheel (hopefully).
The problem I’m having is how to position the ScrollPane in code to reset the image once it reaches either end. So far nothing I have tried to set the scroll position has worked. I’ve tried setScrollX() and scrollTo() methods. I’ve also tried setting the size of the scrollpane to be various sizes (same size as image and two sections smaller than the image). I’ve tried calling layout, invalidate, and pack on the scrollpane to make sure it is laid out correctly before I set the scroll value. I thought that updateVisualScroll() might force it to update the scroll position, but this also has no effect.
No matter what I do it simply ignores all of my calls to change the scroll position so I’m clearly missing something. In my code below I'm trying to get the scrollwheel to start in the center of the image and instead it's starting position is all the way at the left.
I also need to be able to get the current scroll position to detect when it has reached either end. I tried overriding the act() method and printing out scrollPane.getX(), but this value was always “0” even when I manually clicked and dragged it to scroll the ScrollPane.
The scrolling does work when manually clicking and dragging, so I believe the ScrollPane is set up correctly, I just can’t get it to scroll within the code.
Here is my code, and for simplicity I took all of my experimentation code out because none of my experimenting worked.
public class MyScrollWheel extends Container<ScrollPane> {
private ScrollPane scrollPane;
private Image image;
private int scrollOffset;
public MyScrollWheel(){
Texture texture = new Texture(Gdx.files.internal("internal/scrollwheel.png"));
image = new Image(texture);
scrollOffset = (int)(image.getWidth()/14);
scrollPane = new ScrollPane(image);
scrollPane.setOverscroll(false, false);
setActor(scrollPane);
size(image.getWidth()-(scrollOffset*2), image.getHeight());
scrollPane.setScrollX(scrollOffset); // << this doesn't scroll
scrollPane.updateVisualScroll();
}
}

Well, I hopefully managed to get something you can build upon. What I simply did was extending actor and have it accept a Texture so I could use Texture.wrap and have it draw with SpriteBatch.draw(). I am able to keep scrolling it now and based on the scroll delta you can figure out how far it has been scrolled. I don't see any need to reset the wheel but if you really want to you can just do wheel.setScroll(0);.
One limitation is that it is not a Drawable so it cannot be scaled like a NinePatch. You have to give it a plain wheel texture draw it the size you want it to spear, you can add normal scaling however and keep aspect ratio manually. Then add the sides to it and perhaps overlay a gradient on those to create depth.
ScrollWheel:
public class ScrollWheel extends Actor {
Texture wheelTexture;
private int scroll = 0;
public int getScroll() {
return scroll;
}
public void setScroll(int scroll) {
this.scroll = scroll;
}
public ScrollWheel(Texture texture)
{
wheelTexture = texture;
wheelTexture.setWrap(Texture.TextureWrap.Repeat, Texture.TextureWrap.ClampToEdge);
setWidth(texture.getWidth());
setHeight(texture.getHeight());
}
#Override
public void draw(Batch batch, float parentAlpha) {
super.draw(batch, parentAlpha);
batch.draw(wheelTexture, getX(), getY(), scroll, 0,
wheelTexture.getWidth(), wheelTexture.getHeight());
}
}
usage in a Screen:
public class TestScreen implements Screen {
Stage stage;
ScrollWheel wheel;
public TestScreen() {
stage = new Stage();
Table t = new Table();
t.setFillParent(true);
stage.addActor(t);
wheel = new ScrollWheel(new Texture("hud/wheel_part.png"));
wheel.addListener(new DragListener() {
#Override
public void drag(InputEvent event, float x, float y, int pointer) {
super.drag(event, x, y, pointer);
wheel.setScroll(wheel.getScroll() + (int)getDeltaX());
}
});
t.add(wheel);
Gdx.input.setInputProcessor(stage);
}
#Override
public void render(float delta) {
Gdx.gl.glClearColor(.3f, .36f, .42f, 1);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
stage.act();
stage.draw();
}
//...Other mandatory screen methods...
}
So just create a wheel texture that is tillable and include that with the ScrollWheel constructor. It will draw the wheel in the center of the screen if you use this exact code.
The scroll variable essentially holds the amount of scroll so if you you want limit this between 0 and 100 you would just add this functionality in setScroll().
if (scroll > 100) scroll = 100;
else if (scroll < 0) scroll = 0;
You could then add a step to it. So if you want to rotate a image with the slider you could set the rotation by scroll * 3,6f or scroll * (maxScroll / maxStep)
I really liked the way this turned out, I will be using this for my slider in the future :D. I have extended and altered it a bit already and you can see my implementation here: https://youtu.be/RNLk5B-VfYg

Expanding on Menno Gouw's scroll wheel, I've added some more features:
Fling support with setting for fling time
Precision setting to adjust sensitivity of the wheel
Takes a Drawable
Compatible for use inside of a ScrollPane
NOTE: For my purposes I have it take in a Label in the constructor, but this can easily be changed if you don't want it tied to a Label.
Here is a video I recorded on phone demoing the scroll wheel.
https://www.youtube.com/watch?v=RwVrez4BZsY&feature=youtu.be
- EDIT 1: Layout bugs have now been fixed (hopefully). It now updates its position when moved in a ScrollPane and the Drawables are clipped to the border of the Actor.
- EDIT 2: Added support for a stationary drawable for shading and a method to change the wheel's direction (setRightPositiveDirection()).
public class ScrollWheel extends Actor {
private Drawable wheelDrawable, wheelShading;
private Label label;
private int unscaledScrollValueX=0, scrollValueX=0;
private boolean isNotEdge;
private int precision=40;
private int direction=1;
private int minValue=Integer.MIN_VALUE, maxValue=Integer.MAX_VALUE;
// MANUAL SCROLL
private int separator;
private int wheelWidth;
// FLING
private float flingTimer, flingTime=1f;
private float velocityX;
public ScrollWheel(Drawable wheelDrawable, Drawable wheelShading, Label label) {
this.wheelDrawable = wheelDrawable;
this.wheelShading = wheelShading;
this.label = label;
wheelWidth = (int)wheelDrawable.getMinWidth();
separator = wheelWidth;
setWidth(wheelDrawable.getMinWidth());
setHeight(wheelDrawable.getMinHeight());
// stops ScrollPane from overriding input events
InputListener stopTouchDown = new InputListener() {
public boolean touchDown (InputEvent event, float x, float y, int pointer, int button) {
event.stop();
return false;
}
};
addListener(stopTouchDown);
ActorGestureListener flickScrollListener = new ActorGestureListener() {
public void pan (InputEvent event, float x, float y, float deltaX, float deltaY) {
updateScroll(deltaX);
}
public void fling (InputEvent event, float x, float y, int button) {
if (Math.abs(x) > 150) {
flingTimer = flingTime;
velocityX = x;
}
}
public boolean handle (Event event) {
if (super.handle(event)) {
if (((InputEvent)event).getType() == InputEvent.Type.touchDown) flingTimer = 0;
return true;
}
return false;
}
};
addListener(flickScrollListener);
}
private void updateScroll(float delta){
unscaledScrollValueX += (delta * direction);
scrollValueX = (int)(unscaledScrollValueX / precision);
isNotEdge = true;
if (scrollValueX <= minValue){
scrollValueX = minValue;
unscaledScrollValueX = minValue * precision;
isNotEdge = false;
}
else if (scrollValueX >= maxValue){
scrollValueX = maxValue;
unscaledScrollValueX = maxValue * precision;
isNotEdge = false;
}
if (isNotEdge){
separator += delta;
if (separator <= 0){
separator = wheelWidth;
}
else if (separator >= wheelWidth) {
separator = 0;
}
}
updateLabel();
}
private void updateLabel(){
label.setText("" + scrollValueX);
}
public void setMinValue(int minValue){ this.minValue = minValue; }
public void setMinValueToNone(){ minValue=Integer.MIN_VALUE; }
public void setMaxValue(int maxValue){ this.maxValue = maxValue; }
public void setMaxValueToNone(){ minValue=Integer.MAX_VALUE; }
public void setFlingTime(float flingTime){ this.flingTime = flingTime; }
public void setPrecision(int precision){ this.precision = precision; }
public void setRightPositiveDirection(boolean rightPositive){ direction = (rightPositive) ? 1 : -1; }
#Override
public void act(float delta){
super.act(delta);
boolean animating = false;
if (flingTimer > 0) {
float alpha = flingTimer / flingTime;
updateScroll(velocityX * alpha * delta);
flingTimer -= delta;
if (flingTimer <= 0) {
velocityX = 0;
}
animating = true;
}
if (animating) {
Stage stage = getStage();
if (stage != null && stage.getActionsRequestRendering()){
Gdx.graphics.requestRendering();
}
}
}
#Override
public void draw(Batch batch, float parentAlpha){
super.draw(batch, parentAlpha);
batch.flush();
if (clipBegin(getX(), getY(), getWidth(), getHeight())){
wheelDrawable.draw(batch, getX() + separator - wheelWidth, getY(), wheelDrawable.getMinWidth(), wheelDrawable.getMinHeight());
wheelDrawable.draw(batch, getX() + separator, getY(), wheelDrawable.getMinWidth(), wheelDrawable.getMinHeight());
wheelShading.draw(batch, getX(), getY(), wheelShading.getMinWidth(), wheelShading.getMinHeight());
batch.flush();
clipEnd();
}
}
}

Atlas does not render images in order[libGDX]

I am using the following class to render an atlas on screen:
public class AnimationDemo implements ApplicationListener {
private SpriteBatch batch;
private TextureAtlas textureAtlas;
private Animation animation;
private float elapsedTime = 0;
#Override
public void create() {
batch = new SpriteBatch();
textureAtlas = new TextureAtlas(Gdx.files.internal("data/packOne.atlas"));
animation = new Animation(1 / 1f, textureAtlas.getRegions());
}
#Override
public void dispose() {
batch.dispose();
textureAtlas.dispose();
}
#Override
public void render() {
Gdx.gl.glClearColor(0, 0, 0, 1);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
batch.begin();
//sprite.draw(batch);
elapsedTime += Gdx.graphics.getDeltaTime();
batch.draw(animation.getKeyFrame(elapsedTime, true), 0, 0);
batch.end();
}
#Override
public void resize(int width, int height) {
}
#Override
public void pause() {
}
#Override
public void resume() {
}
}
I am a beginner with libGDX, however with the above program my images are not rendered in order as random images appear. I was earlier using the following with the same . atlas file and it was working properly:
public class MyGdxGame implements ApplicationListener {
private SpriteBatch batch;
private TextureAtlas textureAtlas;
private Sprite sprite;
private int currentFrame = 1;
private String currentAtlasKey = new String("0001");
#Override
public void create() {
batch = new SpriteBatch();
textureAtlas = new TextureAtlas(Gdx.files.internal("data/packOne.atlas"));
TextureAtlas.AtlasRegion region = textureAtlas.findRegion("0001");
sprite = new Sprite(region);
sprite.setPosition(Gdx.graphics.getWidth() / 2 - sprite.getWidth() / 2, Gdx.graphics.getHeight() / 2 - sprite.getHeight() / 2);
sprite.scale(4.5f);
Timer.schedule(new Timer.Task() {
#Override
public void run() {
currentFrame++;
if (currentFrame > 393)
currentFrame = 1;
// ATTENTION! String.format() doesnt work under GWT for god knows why...
currentAtlasKey = String.format("%04d", currentFrame);
sprite.setRegion(textureAtlas.findRegion(currentAtlasKey));
}
}
, 0, 1 / 30.0f);
}
#Override
public void dispose() {
batch.dispose();
textureAtlas.dispose();
}
#Override
public void render() {
Gdx.gl.glClearColor(0, 0, 0, 1);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
batch.begin();
sprite.draw(batch);
batch.end();
}
#Override
public void resize(int width, int height) {
}
#Override
public void pause() {
}
#Override
public void resume() {
}
}
Any hints about what might be wrong here?
I am also trying to adapt my program with Screen Viewport any headings as in how to implement this would also be welcome.
Edit: The .atlas file is located here

Your atlas file isn't ordered. If you call the code below, it will be ordered.
regions.sort(new Comparator<AtlasRegion>() {
#Override
public int compare(AtlasRegion o1, AtlasRegion o2) {
return Integer.parseInt(o1.name) > Integer.parseInt(o2.name) ? 1 : -1;
}
});
But I'm still checking why your atlas regions isn't ordered.

you should create array with frames ordered alphabetically instead of using textureAtlas.getRegions() which just gives you an array without caring of order.
The example for atlas with regions named like: region1, region2 and so on would be:
AtlasRegion[] frames = new AtlasRegion[framesCount];
for(int i = 0; i < framesCount; i++)
{
frames[i] = atlas.findRegion("region" + i);
}
so you can adjust it to your regions names.
If you want to get all frames from textureAtlas you can also do it like this:
Array<String> names = new Array<String>();
for(AtlasRegion region : textureAtlas.getRegions())
{
names.add( region.name );
}
names.sort();
Array<AtlasRegion> frames = new Array<AtlasRegion>();
for(String s : names)
{
frames.add( textureAtlas.findRegion(s) );
}
and then after get frames array just create animation object:
animation = new Animation(1/1f, frames.items); //or just frames depending on which type frames is

TexturePacker will index the images for you as long as you follow the naming scheme set forth here https://github.com/libgdx/libgdx/wiki/Texture-packer#image-indexes.
so your frames would be named something like
anim1_001.png
anim1_002.png
...
anim1_100.png
and a separate animation would simply be
anim2_001.png
....
anim2_100.png
EDIT:
additionally you can get the regions only related to certain animations. So instead of
animation = new Animation(1 / 1f, textureAtlas.getRegions());
you could use (yes it's findRegions() not findRegion()):
animation1 = new Animation(1 / 1f, textureAtlas.findRegions("anim1"));
animation2 = new Animation(1 / 1f, textureAtlas.findRegions("anim2"));
EDIT2:
If you're are using a stage it is quite easy to implement a screen viewport. I do it like this, (stage is a field and this step is in the show/create method):
stage = new Stage(new ScreenViewport());
Then in the resize method:
stage.getViewport().update(width, height, true);
Without a stage it's only slightly more complex
camera = new WhateverCamera();
viewport = new ScreenViewport(camera);
Then in the resize method:
viewport.update(width, height, true);
Use whatever camera you want, WhateverCamera is a placeholder and can be OrthographicCamera or PerspectiveCamera.
The last argument true centers the camera, if you don't want to do this set it to false or leave it out, it assumes false.

LibGDX - IllegalArgumentException causes my game to crash whenever my main character touches a Coin

Trying to figure out why my Android game crashes whenever the player touches an animated coin. I have attached an image of the LogCat and my code is below (NOTE: all game objects in ![Renderer] are in an arraylist called toRender. the 2 coins in the game are currently held in the 3rd and 4th position in the list). Renderer and Coin classes respectively:
public class Renderer extends ApplicationAdapter {
private SpriteBatch batch;
private Texture background;
private ArrayList<GameObject> toRender;
private Timer timer;
private float delta;
private Game game;
public Renderer(ArrayList<GameObject> toRender) {
batch = new SpriteBatch();
background = new Texture(Gdx.files.internal("background2.png"));
this.toRender = toRender;
timer = Timer.getInstance();
}
public void collect() {
// for every object in toRender (an arraylist of objects)
for (GameObject o : toRender) {
// if player collides with/collects an object
if (Player.getInstance(null).hasCollected(o)) {
// if its the first coin that he collides with, dispose it
if (o.equals((Coin) toRender.get(3))) {
((Coin) toRender.get(3)).dispose();
}
// if its the second coin that he collides with, dispose it
if (o.equals((Coin) toRender.get(4))) {
((Coin) toRender.get(4)).dispose();
}
}
}
}
public void beginRendering() {
delta = Timer.getInstance().getTime();
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
batch.begin();
batch.draw(background, 0, 0, Gdx.graphics.getWidth(),
Gdx.graphics.getHeight());
timer.drawTime(batch);
for (GameObject object : toRender) {
object.update();
boolean objectIsntCoin = !(object.equals(toRender.get(3)) ||
object.equals(toRender.get(4))); //the 2 coins are in the 3rd and 4th position in the array list
// draw every object's sprite apart from coin, since coin should render the animation rather than the sprite
if (objectIsntCoin) {
object.draw(batch);
}
}
collect();
((Flag) toRender.get(toRender.size() - 1)).drawLevelComplete(batch);
// if the coin exists (i.e. hasn't been disposed), render the animation
if (((Coin) toRender.get(3)).checkExists()) {
((Coin) toRender.get(3)).render(delta);
}
// if the coin exists (i.e. hasn't been disposed), render the animation
if (((Coin) toRender.get(4)).checkExists()) {
((Coin) toRender.get(4)).render(delta);
}
batch.end();
}
}
public class Coin extends GameObject implements Screen {
private SpriteBatch batch;
private Animation animation;
private float time;
private float xPos;
private float yPos;
private Rectangle objectRect;
private boolean exists;
public Coin(Sprite spr, float xPos, float yPos, float radius) {
super(spr, xPos, yPos, radius);
this.xPos = xPos;
this.yPos = yPos;
batch = new SpriteBatch();
objectRect = new Rectangle(getxPos(), getyPos(), getSprite().getWidth(), getSprite().getHeight());
exists = true;
time = 0;
show();
}
public Rectangle getRect() {
return objectRect;
}
public void render(float delta) {
// TODO Auto-generated method stub
batch.begin();
batch.draw(animation.getKeyFrame(time += delta), xPos, yPos);
batch.end();
}
#Override
public void resize(int width, int height) {
}
#Override
public void show() {
animation = new Animation(1 / 8f,
new TextureRegion(new Texture(Gdx.files.internal("coin1.png"))),
new TextureRegion(new Texture(Gdx.files.internal("coin2.png"))),
new TextureRegion(new Texture(Gdx.files.internal("coin3.png"))),
new TextureRegion(new Texture(Gdx.files.internal("coin4.png"))),
new TextureRegion(new Texture(Gdx.files.internal("coin5.png"))),
new TextureRegion(new Texture(Gdx.files.internal("coin6.png"))),
new TextureRegion(new Texture(Gdx.files.internal("coin7.png"))),
new TextureRegion(new Texture(Gdx.files.internal("coin8.png"))));
animation.setPlayMode(Animation.PlayMode.LOOP);
}
#Override
public void hide() {
}
#Override
public void pause() {
}
#Override
public void resume() {
}
#Override
public void dispose() {
batch.dispose();
exists = false;
}
public boolean checkExists() {
return exists;
}
}
LogCat:1
So the errors that the LogCat point to:
1)dispose() method in Coin:
batch.dispose();
2)collect() method in Renderer:
if(o.equals((Coin) toRender.get(3))) {
3)beginRendering() method in Renderer:
for (GameObject object : toRender) {
Does anyone know why my program is crashing? I just want the animated coin to disappear when the Player touches it. Currently the coin DOES disappear, the application just shuts down immediately after though. Have been stuck on this for a while so any insight is highly appreciated.
Thank you in advance.

First, I want to mention that downcasting the objects in toRender like you are is both dangerous and indicates there is a flaw in your design. Additionally, you'll notice that equals(Object) accepts an Object as an argument; you don't need to cast it to Coin.
Anyway, the reason your program is crashing is explained in the IllegalArgumentException message,
buffer not allocated with newUnsafeByteBuffer or already disposed.
You're trying to dispose your Coin's batch when it has already been disposed.
In your collect() method, you loop through the objects, and you dispose of their batches, but the Coin objects themselves are never removed from your toRender list. So, the next time collect() is called, it will loop through those same Coin objects and try to dispose of them again, and an exception is thrown.
The solution is to remove the Coin objects from your toRender list when they no longer belong in your game's scene. However, you can't remove an element from a list while you're iterating over it, as this would disrupt the loop. Instead, remove them like so:
public void collect() {
// Holds the Coins we want to remove from toRender
final Collection<GameObject> toRemove = new LinkedList<>();
for (GameObject o : toRender) {
if (Player.getInstance(null).hasCollected(o)) {
if (o.equals(toRender.get(3))) {
final Coin coin = (Coin) toRender.get(3);
coin.dispose();
toRemove.add(coin);
}
if (o.equals(toRender.get(4))) {
final Coin coin = (Coin) toRender.get(4);
coin.dispose();
toRemove.add(coin);
}
}
}
// Remove the collected Coins
toRender.removeAll(toRemove);
}