Kotlin pour le développement d’un jeu avec libGDX : avantage & inconvénient

libGDX est un framework de développement de jeux vidéo Java. Mais quand on développe un jeu, on veut se concentrer sur le design du jeu, itérer rapidement : on ne veut pas perdre de temps avec des problèmes de syntaxes ou autre. Mais Kotlin s’intègre t’il facilement avec les APIs Java de libGDX ? Qu’apporte Kotlin dans ce contexte et surtout. Les avantages de Kotlin sont-ils toujours des avantages dans le code d’un jeu vidéo ?

(Kotlin Paris Meetup - https://www.meetup.com/fr-FR/Kotlin-Paris-Meetup/events/247733641/ )

Transcript

1. Kotlin pour le développement
   d’un jeu avec libGDX
   Avantages & inconvénients
   

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2. David
   Wursteisen
   

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4. John Carmack
   

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10. ❤
    

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11. PRODUCTIVITYYYYYYYY
    

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12. Core
    iOS GWT
    Android
    Desktop
    
    

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13. Core
    Android
    Desktop
    

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14. class HelloWorld : ScreenAdapter() {
    override fun show() {
    }
    override fun render(delta: Float) {
    }
    }
    Initialisation de l’écran
    de jeu
    Rendu de l’écran de jeu
    

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15. class HelloWorld : ScreenAdapter() {
    var batch: SpriteBatch?
    override fun show() {
    batch = SpriteBatch()
    }
    override fun render(delta: Float) {
    batch!!.begin()
    // ...
    batch!!.end()
    }
    }
    

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16. class HelloWorld : ScreenAdapter() {
    var batch: SpriteBatch?
    override fun show() {
    batch = SpriteBatch()
    }
    override fun render(delta: Float) {
    batch!!.begin()
    // ...
    batch!!.end()
    }
    }
    
    

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17. class HelloWorld : ScreenAdapter() {
    lateinit var batch: SpriteBatch
    override fun show() {
    batch = SpriteBatch()
    }
    override fun render(delta: Float) {
    batch.begin()
    // ...
    batch.end()
    }
    }
    

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18. class HelloWorld : ScreenAdapter() {
    lateinit var batch: SpriteBatch
    override fun show() {
    batch = SpriteBatch()
    }
    override fun render(delta: Float) {
    batch.begin()
    // ...
    batch.end()
    }
    }
    

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19. fun String.toColor(): Color = Color.valueOf(this)
    val background = « 0089d5".toColor()
    fun ShapeRenderer.rect(pos: Vector2, size: Vector2) {
    this.rect(pos.x, pos.y, size.x, size.y)
    }
    batch.rect(pos1, pos2)
    

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20. fun String.toColor(): Color = Color.valueOf(this)
    val background = « 0089d5".toColor()
    fun ShapeRenderer.rect(pos: Vector2, size: Vector2) {
    this.rect(pos.x, pos.y, size.x, size.y)
    }
    batch.rect(pos1, pos2)
    Méthode d’extension
    =
    étendre une API à
    son besoin
    

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21. Hexagonal Architecture ?
    

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22. object EntityFactory {
    fun player(engine: PooledEngine, assets: AssetManager): Unit {
    // …
    }
    Couplage !
    Couplage !
    

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23. const val TOUCH_DOWN = 1
    const val TOUCH_UP = 2
    const val TOUCH_MOVE = 3
    Compile-Time Constants
    Properties the value of which is known at compile time can be marked as compile time
    constants using the const modifier. Such properties need to fulfil the following requirements:
    Top-level or member of an object
    Initialized with a value of type String or a primitive type
    No custom getter
    

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24. private void readMeasureHeader(InputStream is, int measureIndex) throws IOException {
    int header = helper.readUnsignedByte(is);
    boolean repeatStart = ((header & ParserHelper.BITMASK_3) != 0);
    boolean doubleBar = ((header & ParserHelper.BITMASK_8) != 0);
    int numerator = 0;
    if ((header & ParserHelper.BITMASK_1) != 0) {
    numerator = helper.readByte(is);
    }
    int denominator = 0;
    if ((header & ParserHelper.BITMASK_2) != 0) {
    denominator = helper.readByte(is);
    }
    }
    

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25. private void readMeasureHeader(InputStream is, int measureIndex) throws IOException {
    int header = helper.readUnsignedByte(is);
    boolean repeatStart = ((header & ParserHelper.BITMASK_3) != 0);
    boolean doubleBar = ((header & ParserHelper.BITMASK_8) != 0);
    int numerator = 0;
    if ((header & ParserHelper.BITMASK_1) != 0) {
    numerator = helper.readByte(is);
    }
    int denominator = 0;
    if ((header & ParserHelper.BITMASK_2) != 0) {
    denominator = helper.readByte(is);
    }
    }
    

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26. TOUCH_DOWN shl 3
    TOUCH_DOWN and 2
    TOUCH_DOWN << 3
    TOUCH_DOWN & 2
    

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27. Direction
    Position
    

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28. Vector2(3f, 5f).set(entity[cameraData].direction)
    .scl(5f)
    .add(entity[position].value)
    .add(halfX, halfY
    val v1 = Vector2(3f, 5f) + Vector2(4f, 2f)
    v2 = v1 * 5f
    

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29. Vector2(3f, 5f).set(entity[cameraData].direction)
    .scl(5f)
    .add(entity[position].value)
    .add(halfX, halfY
    val v1 = Vector2(3f, 5f) + Vector2(4f, 2f)
    v2 = v1 * 5f
    Surcharge d’opérateur (add)
    Surcharge d’opérateur (scl)
    

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30. engine.addEntity({ e ->
    val left = spriteDef.slices("left")
    val leftRegion = left.textureRegion(assets["sheets/pico8/keyboard.png"])
    e.add(Controller())
    e.add(Position(42 v2 26))
    e.add(Size(16 v2 16))
    e.add(EntityRender(texture = leftRegion))
    e.add(ButtonComponent(ButtonSystem.LEFT))
    e.add(StateComponent())
    })
    Vector2
    

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31. engine.addEntity({ e ->
    val left = spriteDef.slices("left")
    val leftRegion = left.textureRegion(assets["sheets/pico8/keyboard.png"])
    e.add(Controller())
    e.add(Position(42 v2 26))
    e.add(Size(16 v2 16))
    e.add(EntityRender(texture = leftRegion))
    e.add(ButtonComponent(ButtonSystem.LEFT))
    e.add(StateComponent())
    })
    infix fun Int.v2(that: Int): Vector2 = Vector2(this.toFloat(), that.toFloat())
    

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34. Position
    Couleur
    Joueur
    Etat
    

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35. val player = Entity()
    player.add(Player()))
    player.add(Position(100 v2 100))
    player.add(ColorSplash(Color.GREEN))
    player.add(StateComponent())
    Position
    Couleur
    Joueur
    Etat
    

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36. ComponentMapper pm = ComponentMapper.getFor(PositionComponent.class);
    ComponentMapper vm = ComponentMapper.getFor(VelocityComponent.class);
    ...
    PositionComponent position = pm.get(entity);
    VelocityComponent velocity = vm.get(entity);
    Extracteur
    Extraction
    

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37. inline fun EntitySystem.get(): ComponentMapper = ComponentMapper.getFor(T::class.java)
    private val move: ComponentMapper = ComponentMapper.getFor(TurnMove::class.java)
    Extracteur
    

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38. inline fun EntitySystem.get(): ComponentMapper = ComponentMapper.getFor(T::class.java)
    private val move: ComponentMapper = ComponentMapper.getFor(TurnMove::class.java)
    Inline + reified
    

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39. inline fun EntitySystem.get(): ComponentMapper = ComponentMapper.getFor(T::class.java)
    private val move: ComponentMapper = get()
    

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40. private val move: ComponentMapper = get()
    private val position: ComponentMapper = get()
    private val state: ComponentMapper = get()
    private val direction: ComponentMapper = get()
    

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41. PositionComponent position = pm.get(entity);
    Extraction
    

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42. val position: Position = pm.get(entity)
    

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43. val position: Position = entity.get(pm)
    

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44. val position: Position = entity[pm]
    

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45. entity[move].turn(entity[direction].value)
    entity[state].time = 0f
    entity[animated].animation = animation["dragon_move"]
    Direction
    Etat
    …
    

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46. public void render(float delta) {

    movePlayer(delta);

    moveEnemies(delta);

    moveWorld(delta);

    

    renderWorld();

    renderEnemies();

    renderPlayer();

    }
    

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47. public void render(float delta) {

    movePlayer(delta);

    moveEnemies(delta);

    moveWorld(delta);

    

    renderWorld();

    renderEnemies();

    renderPlayer();

    }
    60x

    secondes
    

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48. Garbage Collector
    Garbage Collector
    Garbage Collector
    Garbage Collecto
    arbage C
    Garbage
    STOP THE
    WORLD
    

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49. altLayers = map.layers
    .mapIndexed { index, layer -> index to layer }
    .filter { it.second.name.startsWith("alt_") }
    .map { it.first }
    .toIntArray()
    
    mutableList !
    
    

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50. val a = Array(5, { "" })
    val b = Array()
    Différence ?
    Array libGDX
    

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51. import com.badlogic.gdx.utils.Array as GdxArray
    val a = Array(5, { "" })
    val b = GdxArray()
    

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52. interface EventListener {
    fun onEvent(event: Event, eventData: EventData)
    }
    fun register(eventListener: EventListener, vararg events: Event) {
    events.forEach {
    val lst = listeners[it]
    if (lst == null) {
    listeners.put(it, listOf(eventListener))
    } else {
    listeners.put(it, lst + eventListener)
    }
    }
    }
    

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53. interface EventListener {
    fun onEvent(event: Event, eventData: EventData)
    }
    fun register(eventListener: EventListener, vararg events: Event) {
    events.forEach {
    val lst = listeners[it]
    if (lst == null) {
    listeners.put(it, listOf(eventListener))
    } else {
    listeners.put(it, lst + eventListener)
    }
    }
    }
    Interface avec une
    méthode
    

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54. eventBus.register(object : EventListener {
    override fun onEvent(event: Event, eventData: EventData) {
    game.loadingScreen()
    }
    }, GameEvents.EVENT_GAME_MAIN_MENU)
    Class anonyme
    

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55. fun on(event: Int, block: Transition): OnState {
    var currentTransitions = parent.transitions[state] ?: emptyMap()
    currentTransitions += event to block
    parent.transitions += state to currentTransitions
    return this
    }
    Lambda
    

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56. startWith(WAIT)
    onState(WAIT).on(GameEvents.EVENT_COMPUTER_ALLOW_MOVE) { entity, event ->
    if (entity[dragon].currentTurn > 3) {
    entity[dragon].currentTurn = -1
    go(FIRE, entity, event)
    } else {
    go(MOVE, entity, event)
    }
    }
    onState(FIRE).on(GameEvents.EVENT_DRAGON_FIRE_BALL) { entity, event ->
    go(MOVE, entity, event)
    }
    Lambda
    

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57. startWith(WAIT)
    onState(WAIT).on(GameEvents.EVENT_COMPUTER_ALLOW_MOVE) { entity, event ->
    if (entity[dragon].currentTurn > 3) {
    entity[dragon].currentTurn = -1
    go(FIRE, entity, event)
    } else {
    go(MOVE, entity, event)
    }
    }
    onState(FIRE).on(GameEvents.EVENT_DRAGON_FIRE_BALL) { entity, event ->
    go(MOVE, entity, event)
    }
    Etat Event Transition
    

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58. ❤
    

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59. On reste en contact ?
    @dwursteisen
    

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60. https://goo.gl/4UcQYx
    En attendant… téléchargez 

    Wiz le magicien 

    sur le Play Store Android
    

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