Beat the high-score: build a game using libGDX and Kotlin

Beat the high-score: build a game using libGDX and Kotlin

Playing games is fun but making games is even better, especially with Kotlin and libGDX. Let's build together a breakout game and let's explore the gaming framework libGDX.

This session will show some libGDX's concepts: how to draw and animate elements of our game, how collision system works to destroy our bricks, what Kotlin brings to libGDX. Then we will dive into more advanced topics like shaders, in order to handle pixels from our images. Why are we doing all of this? To break the high score, of course!

Kyiv Kotlin Night (1th june 2019)

7843bb075c05be6886a97b77e36758ff?s=128

David

June 01, 2019
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Transcript

  1. Build a game using libGDX and Kotlin Build a game

    using libGDX and Kotlin Build a game using libGDX and Kotlin Build a game using libGDX and Kotlin Beat the High score Beat the High score Build a game using libGDX and Kotlin
  2. -Gilles Allain In a farm… far, far away…

  3. -Gilles Allain a sneaky fox appears in the darkness of

    the night.
  4. None
  5. -Gilles Allain In a mighty move, he stole all the

    chickens of the farm...
  6. None
  7. -Gilles Allain those chickens were our...friends.

  8. -Gilles Allain the same night, a lightning strikes you!

  9. None
  10. -Gilles Allain ...this lightning has given you power to bring

    back... ...our friends!
  11. Let's help him !
 (by making a game)

  12. David Wursteisen

  13. None
  14. None
  15. John Carmack

  16. None
  17. None
  18. Rota Pong

  19. Wiz 
 The Wizard

  20. Beat 
 The High 
 Score

  21. Game engines

  22. None
  23. Pavel Quest Destroy Blocks Mirage Realms

  24. Hair Dash - http://cleancutgames.com/

  25. None
  26. None
  27. None
  28. Core iOS GWT Android Desktop

  29. dependencies { compile "com.badlogicgames.gdx:gdx:$gdxVersion" compile "com.badlogicgames.gdx:gdx-box2d:$gdxVersion" compile "com.badlogicgames.ashley:ashley:$ashleyVersion" compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlinVersion"

    compile "io.github.libktx:ktx-ashley:$ktxVersion" compile "io.github.libktx:ktx-graphics:$ktxVersion" compile "io.github.libktx:ktx-scene2d:$ktxVersion" compile "io.github.libktx:ktx-log:$ktxVersion" compile "com.github.dwursteisen.libgdx-addons:aseprite-addons:$libgdx_addons" compile "com.github.dwursteisen.libgdx-addons:ashley-addons:$libgdx_addons" compile "com.strongjoshua:libgdx-inGameConsole:$console" }
  30. dependencies { compile "com.badlogicgames.gdx:gdx:$gdxVersion" compile "com.badlogicgames.gdx:gdx-box2d:$gdxVersion" compile "com.badlogicgames.ashley:ashley:$ashleyVersion" compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlinVersion"

    compile "io.github.libktx:ktx-ashley:$ktxVersion" compile "io.github.libktx:ktx-graphics:$ktxVersion" compile "io.github.libktx:ktx-scene2d:$ktxVersion" compile "io.github.libktx:ktx-log:$ktxVersion" compile "com.github.dwursteisen.libgdx-addons:aseprite-addons:$libgdx_addons" compile "com.github.dwursteisen.libgdx-addons:ashley-addons:$libgdx_addons" compile "com.strongjoshua:libgdx-inGameConsole:$console" }
  31. dependencies { compile "com.badlogicgames.gdx:gdx:$gdxVersion" compile "com.badlogicgames.gdx:gdx-box2d:$gdxVersion" compile "com.badlogicgames.ashley:ashley:$ashleyVersion" compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlinVersion"

    compile "io.github.libktx:ktx-ashley:$ktxVersion" compile "io.github.libktx:ktx-graphics:$ktxVersion" compile "io.github.libktx:ktx-scene2d:$ktxVersion" compile "io.github.libktx:ktx-log:$ktxVersion" compile "com.github.dwursteisen.libgdx-addons:aseprite-addons:$libgdx_addons" compile "com.github.dwursteisen.libgdx-addons:ashley-addons:$libgdx_addons" compile "com.strongjoshua:libgdx-inGameConsole:$console" }
  32. dependencies { compile "com.badlogicgames.gdx:gdx:$gdxVersion" compile "com.badlogicgames.gdx:gdx-box2d:$gdxVersion" compile "com.badlogicgames.ashley:ashley:$ashleyVersion" compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlinVersion"

    compile "io.github.libktx:ktx-ashley:$ktxVersion" compile "io.github.libktx:ktx-graphics:$ktxVersion" compile "io.github.libktx:ktx-scene2d:$ktxVersion" compile "io.github.libktx:ktx-log:$ktxVersion" compile "com.github.dwursteisen.libgdx-addons:aseprite-addons:$libgdx_addons" compile "com.github.dwursteisen.libgdx-addons:ashley-addons:$libgdx_addons" compile "com.strongjoshua:libgdx-inGameConsole:$console" }
  33. dependencies { compile "com.badlogicgames.gdx:gdx:$gdxVersion" compile "com.badlogicgames.gdx:gdx-box2d:$gdxVersion" compile "com.badlogicgames.ashley:ashley:$ashleyVersion" compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlinVersion"

    compile "io.github.libktx:ktx-ashley:$ktxVersion" compile "io.github.libktx:ktx-graphics:$ktxVersion" compile "io.github.libktx:ktx-scene2d:$ktxVersion" compile "io.github.libktx:ktx-log:$ktxVersion" compile "com.github.dwursteisen.libgdx-addons:aseprite-addons:$libgdx_addons" compile "com.github.dwursteisen.libgdx-addons:ashley-addons:$libgdx_addons" compile "com.strongjoshua:libgdx-inGameConsole:$console" }
  34. Let’s make a game!

  35. public void render(float delta) {
 movePlayer(delta);
 moveEnemies(delta);
 moveWorld(delta);
 
 renderWorld();


    renderEnemies();
 renderPlayer();
 }
  36. public void render(float delta) {
 movePlayer(delta);
 moveEnemies(delta);
 moveWorld(delta);
 
 renderWorld();


    renderEnemies();
 renderPlayer();
 }
  37. public void render(float delta) {
 movePlayer(delta);
 moveEnemies(delta);
 moveWorld(delta);
 
 renderWorld();


    renderEnemies();
 renderPlayer();
 }
  38. public void render(float delta) {
 movePlayer(delta);
 moveEnemies(delta);
 moveWorld(delta);
 
 renderWorld();


    renderEnemies();
 renderPlayer();
 } 60x
 seconds
  39. None
  40. class MyScreen : ScreenAdapter() { lateinit var batch: SpriteBatch override

    fun create() { batch = SpriteBatch() } override fun render() { batch.begin() batch.draw(image, x, y) batch.end() } }
  41. class MyScreen : ScreenAdapter() { lateinit var batch: SpriteBatch override

    fun create() { batch = SpriteBatch() } override fun render() { batch.begin() batch.draw(image, x, y) batch.end() } }
  42. class MyScreen : ScreenAdapter() { lateinit var batch: SpriteBatch override

    fun create() { batch = SpriteBatch() } override fun render() { batch.begin() batch.draw(image, x, y) batch.end() } }
  43. class MyScreen : ScreenAdapter() { lateinit var batch: SpriteBatch override

    fun create() { batch = SpriteBatch() } override fun render() { batch.begin() batch.draw(image, x, y) batch.end() } }
  44. class MyScreen : ScreenAdapter() { lateinit var batch: ShapeRenderer override

    fun create() { batch = ShapeRenderer() } override fun render() { batch.begin(ShapeRenderer.ShapeType.Filled) batch.color = Color.CHARTREUSE batch.circle(x, y, radius) batch.end() } }
  45. class MyScreen : ScreenAdapter() { lateinit var batch: ShapeRenderer override

    fun create() { batch = ShapeRenderer() } override fun render() { batch.begin(ShapeRenderer.ShapeType.Filled) batch.color = Color.CHARTREUSE batch.circle(x, y, radius) batch.end() } }
  46. class MyScreen : ScreenAdapter() { lateinit var batch: ShapeRenderer override

    fun create() { batch = ShapeRenderer() } override fun render() { batch.begin(ShapeRenderer.ShapeType.Filled) batch.color = Color.CHARTREUSE batch.circle(x, y, radius) batch.end() } }
  47. class MyScreen : ScreenAdapter() { lateinit var batch: ShapeRenderer override

    fun create() { batch = ShapeRenderer() } override fun render() { batch.begin(ShapeRenderer.ShapeType.Filled) batch.color = Color.CHARTREUSE batch.circle(x, y, radius) batch.end() } }
  48. class MyScreen : ScreenAdapter() { lateinit var batch: SpriteBatch override

    fun create() { batch = SpriteBatch() } override fun render() { batch.begin() batch.draw(image, x, y) batch.end() } }
  49. class MyScreen : KtxScreen { val batch: SpriteBatch = SpriteBatch()

    override fun render() { batch.use { it.draw(sprite, x, y) } } } Inherit
  50. (0,0) x y

  51. class MyScreen : ScreenAdapter() { lateinit var batch: ShapeRenderer private

    val position: Vector2 = Vector2(0f, 0f) override fun create() { batch = ShapeRenderer() } override fun render(delta: Float) { position.add(0f, -0.5f) batch.begin(ShapeRenderer.ShapeType.Filled) batch.color = Color.CHARTREUSE batch.circle(position.x, position.y, radius) batch.end() } }
  52. class MyScreen : ScreenAdapter() { lateinit var batch: ShapeRenderer private

    val position: Vector2 = Vector2(0f, 0f) override fun create() { batch = ShapeRenderer() } override fun render(delta: Float) { position.add(0f, -0.5f) batch.begin(ShapeRenderer.ShapeType.Filled) batch.color = Color.CHARTREUSE batch.circle(position.x, position.y, radius) batch.end() } }
  53. class MyScreen : ScreenAdapter() { lateinit var batch: ShapeRenderer private

    val position: Vector2 = Vector2(0f, 0f) override fun create() { batch = ShapeRenderer() } override fun render(delta: Float) { position.add(0f, -0.5f) batch.begin(ShapeRenderer.ShapeType.Filled) batch.color = Color.CHARTREUSE batch.circle(position.x, position.y, radius) batch.end() } }
  54. class MyScreen : ScreenAdapter() { lateinit var batch: ShapeRenderer private

    val position: Vector2 = Vector2(0f, 0f) override fun create() { batch = ShapeRenderer() } override fun render(delta: Float) { position.add(0f, -0.5f) batch.begin(ShapeRenderer.ShapeType.Filled) batch.color = Color.CHARTREUSE batch.circle(position.x, position.y, radius) batch.end() } }
  55. class MyScreen : ScreenAdapter() { lateinit var batch: ShapeRenderer private

    val position: Vector2 = Vector2(0f, 0f) private var time: Float = 0f override fun create() { batch = ShapeRenderer() } override fun render(delta: Float) { val (x, y) = position time += delta batch.begin(ShapeRenderer.ShapeType.Filled) batch.color = Color.CHARTREUSE batch.circle(x + MathUtils.cos(time), y, radius) batch.end() } }
  56. class MyScreen : ScreenAdapter() { lateinit var batch: ShapeRenderer private

    val position: Vector2 = Vector2(0f, 0f) private var time: Float = 0f override fun create() { batch = ShapeRenderer() } override fun render(delta: Float) { val (x, y) = position time += delta batch.begin(ShapeRenderer.ShapeType.Filled) batch.color = Color.CHARTREUSE batch.circle(x + MathUtils.cos(time), y, radius) batch.end() } }
  57. class MyScreen : ScreenAdapter() { lateinit var batch: ShapeRenderer private

    val position: Vector2 = Vector2(0f, 0f) private var time: Float = 0f override fun create() { batch = ShapeRenderer() } override fun render(delta: Float) { val (x, y) = position time += delta batch.begin(ShapeRenderer.ShapeType.Filled) batch.color = Color.CHARTREUSE batch.circle(x + MathUtils.cos(time), y, radius) batch.end() } }
  58. class MyScreen : ScreenAdapter() { lateinit var batch: ShapeRenderer private

    val position: Vector2 = Vector2(0f, 0f) private var time: Float = 0f override fun create() { batch = ShapeRenderer() } override fun render(delta: Float) { val (x, y) = position time += delta batch.begin(ShapeRenderer.ShapeType.Filled) batch.color = Color.CHARTREUSE batch.circle(x + MathUtils.cos(time), y, radius) batch.end() } }
  59. /** * Operator function that allows to deconstruct this vector.

    * @return X component. */ operator fun Vector2.component1(): Float = this.x /** * Operator function that allows to deconstruct this vector. * @return Y component. */ operator fun Vector2.component2(): Float = this.y val vector = Vector2(45f, 50f) val (x, y) = vector
  60. /** * Operator function that allows to deconstruct this vector.

    * @return X component. */ operator fun Vector2.component1(): Float = this.x /** * Operator function that allows to deconstruct this vector. * @return Y component. */ operator fun Vector2.component2(): Float = this.y val (x, y) = Vector2(45f, 50f)
  61. entity.add(Ball()) .add(Position(Vector2(-100f, -100f))) .add(Size(Vector2(8f, 9f))) .add(Rotation(Vector2(4f, 4f)))

  62. entity.add(Ball()) .add(Position(Vector2(-100f, -100f))) .add(Size(Vector2(8f, 9f))) .add(Rotation(Vector2(4f, 4f)))

  63. entity.add(Ball()) .add(Position(-100 v2 -100f)) .add(Size(8 v2 9)) .add(Rotation(4 v2 4))

    Create a 
 new Vector2 infix fun Number.v2(other: Number): Vector2 { return Vector2(this.toFloat(), other.toFloat()) }
  64. Math: back to school

  65. None
  66. Side Racket Ball

  67. Racket Side Side Ball

  68. Racket Side Side Ball dx = dx * -1

  69. Racket Side Side Ball dx = dx * -1

  70. Racket Side Side Ball Alpha dy = dy * -1

    * alpha dx = dx * alpha
  71. val alpha = Math.abs(ball.x - raquet.x) val direction: Vector2 =

    Vector2(10f, 20f) direction.scl(1f, -1f) .scl(alpha) .nor() .rotate(306f) .add(10f, 20f)
  72. val ball = Rectangle(68f, 64f, 5f, 5f) val player =

    Rectangle(64f, 64f, 100f, 10f) // the ball hit the player? player.overlaps(ball)
  73. val ball = Rectangle(68f, 64f, 5f, 5f) val player =

    Rectangle(64f, 64f, 100f, 10f) // the ball hit the player? player.overlaps(ball)
  74. val ball = Rectangle(68f, 64f, 5f, 5f) val player =

    Rectangle(64f, 64f, 100f, 10f) // the ball hit the player? player.overlaps(ball)
  75. None
  76. None
  77. None
  78. Box2D

  79. var world = World(Vector2(0, -10), true) // ... // Do

    in render method world.step(1/60f, 6, 2); val bodyDef = BodyDef() // Set its world position bodyDef.position.set(position.x, position.y) bodyDef.type = BodyDef.BodyType.DynamicBody bodyDef.angle = 0f val body = world.createBody(bodyDef) val shape = CircleShape() shape.radius = 8f // 2. Create a FixtureDef, as usual. val fd = FixtureDef() fd.density = 1f fd.friction = 2f fd.shape = shape body.createFixture(fd) body.userData = Any // attach sprite data shape.dispose()
  80. var world = World(Vector2(0, -10), true) // ... // Do

    in render method world.step(1/60f, 6, 2); val bodyDef = BodyDef() // Set its world position bodyDef.position.set(position.x, position.y) bodyDef.type = BodyDef.BodyType.DynamicBody bodyDef.angle = 0f val body = world.createBody(bodyDef) val shape = CircleShape() shape.radius = 8f // 2. Create a FixtureDef, as usual. val fd = FixtureDef() fd.density = 1f fd.friction = 2f fd.shape = shape body.createFixture(fd) body.userData = Any // attach sprite data shape.dispose() Gravity
  81. var world = World(Vector2(0, -10), true) // ... // Do

    in render method world.step(1/60f, 6, 2); val bodyDef = BodyDef() // Set its world position bodyDef.position.set(position.x, position.y) bodyDef.type = BodyDef.BodyType.DynamicBody bodyDef.angle = 0f val body = world.createBody(bodyDef) val shape = CircleShape() shape.radius = 8f // 2. Create a FixtureDef, as usual. val fd = FixtureDef() fd.density = 1f fd.friction = 2f fd.shape = shape body.createFixture(fd) body.userData = Any // attach sprite data shape.dispose()
  82. var world = World(Vector2(0, -10), true) // ... // Do

    in render method world.step(1/60f, 6, 2); val bodyDef = BodyDef() // Set its world position bodyDef.position.set(position.x, position.y) bodyDef.type = BodyDef.BodyType.DynamicBody bodyDef.angle = 0f val body = world.createBody(bodyDef) val shape = CircleShape() shape.radius = 8f // 2. Create a FixtureDef, as usual. val fd = FixtureDef() fd.density = 1f fd.friction = 2f fd.shape = shape body.createFixture(fd) body.userData = Any // attach sprite data shape.dispose() Configuration of the « thing »
  83. var world = World(Vector2(0, -10), true) // ... // Do

    in render method world.step(1/60f, 6, 2); val bodyDef = BodyDef() // Set its world position bodyDef.position.set(position.x, position.y) bodyDef.type = BodyDef.BodyType.DynamicBody bodyDef.angle = 0f val body = world.createBody(bodyDef) val shape = CircleShape() shape.radius = 8f // 2. Create a FixtureDef, as usual. val fd = FixtureDef() fd.density = 1f fd.friction = 2f fd.shape = shape body.createFixture(fd) body.userData = Any // attach sprite data shape.dispose()
  84. var world = World(Vector2(0, -10), true) // ... // Do

    in render method world.step(1/60f, 6, 2); val bodyDef = BodyDef() // Set its world position bodyDef.position.set(position.x, position.y) bodyDef.type = BodyDef.BodyType.DynamicBody bodyDef.angle = 0f val body = world.createBody(bodyDef) val shape = CircleShape() shape.radius = 8f // 2. Create a FixtureDef, as usual. val fd = FixtureDef() fd.density = 1f fd.friction = 2f fd.shape = shape body.createFixture(fd) body.userData = Any // attach sprite data shape.dispose()
  85. var world = World(Vector2(0, -10), true) // ... // Do

    in render method world.step(1/60f, 6, 2); val bodyDef = BodyDef() // Set its world position bodyDef.position.set(position.x, position.y) bodyDef.type = BodyDef.BodyType.DynamicBody bodyDef.angle = 0f val body = world.createBody(bodyDef) val shape = CircleShape() shape.radius = 8f // 2. Create a FixtureDef, as usual. val fd = FixtureDef() fd.density = 1f fd.friction = 2f fd.shape = shape body.createFixture(fd) body.userData = Any // attach sprite data shape.dispose()
  86. Traversable

  87. Math: Interpolation

  88. None
  89. None
  90. None
  91. y = Interpolation.bounceOut.apply(time) * 100f Non linear Should be a

    percentage (0..1) y will go from 0 to 100
  92. The screen, the viewport 
 and the camera

  93. Game screen screen screen screen screen

  94. open class MenuScreen(val game: Game) : ScreenAdapter() { override fun

    render(delta: Float) { // clear the screen Gdx.gl.glClearColor(0f, 0f, 0f, 1f) Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT) batch.begin() // ... batch.end() if (goToMenu) { game.setScreen(menuScreen) } } }
  95. open class MenuScreen(val game: Game) : ScreenAdapter() { override fun

    render(delta: Float) { // clear the screen Gdx.gl.glClearColor(0f, 0f, 0f, 1f) Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT) batch.begin() // ... batch.end() if (goToMenu) { game.setScreen(menuScreen) } } } ⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠ game.setScreen(screen) 
 is not the same that
 game.screen = screen ⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠
  96. None
  97. None
  98. None
  99. class MyScreen : ScreenAdapter() { private lateinit var viewport: Viewport

    private lateinit var bath: SpriteBatch override fun show() { viewport = FitViewport(200f, 200f) bath = SpriteBath() } override fun render(delta: Float) { Gdx.gl.glClearColor(91f / 256f, 110f / 256f, 225f / 256f, 1f) Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT) batch.begin() batch.projectionMatrix = viewport.camera.combined // render batch.end() } override fun resize(width: Int, height: Int) { viewport.update(width, height) } }
  100. class MyScreen : ScreenAdapter() { private lateinit var viewport: Viewport

    private lateinit var bath: SpriteBatch override fun show() { viewport = FitViewport(200f, 200f) bath = SpriteBath() } override fun render(delta: Float) { Gdx.gl.glClearColor(91f / 256f, 110f / 256f, 225f / 256f, 1f) Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT) batch.begin() batch.projectionMatrix = viewport.camera.combined // render batch.end() } override fun resize(width: Int, height: Int) { viewport.update(width, height) } } Size of the world you’ll display on the screen
  101. class MyScreen : ScreenAdapter() { private lateinit var viewport: Viewport

    private lateinit var bath: SpriteBatch override fun show() { viewport = FitViewport(200f, 200f) bath = SpriteBath() } override fun render(delta: Float) { Gdx.gl.glClearColor(91f / 256f, 110f / 256f, 225f / 256f, 1f) Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT) batch.begin() batch.projectionMatrix = viewport.camera.combined // render batch.end() } override fun resize(width: Int, height: Int) { viewport.update(width, height) } }
  102. None
  103. ScreenViewport

  104. StretchViewport

  105. FitViewport Clear this zone Clear this zone

  106. FillViewport

  107. ExtendViewport Displaying this zone

  108. None
  109. None
  110. viewport.camera.position.add(0f, 40f, 0f) // Recalculates the projection and // view

    matrix of this camera // Use this after you've manipulated any of // the attributes of the camera. viewport.camera.update() viewport.camera.rotate(10f, 0f, 0f, 1f) viewport.camera.update()
  111. viewport.camera.position.add(0f, 40f, 0f) // Recalculates the projection and // view

    matrix of this camera // Use this after you've manipulated any of // the attributes of the camera. viewport.camera.update() viewport.camera.rotate(10f, 0f, 0f, 1f) viewport.camera.update() Will move the camera up
  112. viewport.camera.position.add(0f, 40f, 0f) // Recalculates the projection and // view

    matrix of this camera // Use this after you've manipulated any of // the attributes of the camera. viewport.camera.update() viewport.camera.rotate(10f, 0f, 0f, 1f) viewport.camera.update() Rotate the camera on the z Axis
  113. Around the game

  114. None
  115. None
  116. // load texture val texture = Texture(Gdx.files.internal("texture.png")) val split =

    TextureRegion.split(texture, 128, 128) // select frames val frames = Array<TextureRegion>() frames.add(split[0][0]) frames.add(split[0][1]) frames.add(split[0][2]) frames.add(split[0][4]) // create animation val animation = Animation<TextureRegion>(100f, frames) // select frame to draw val keyToRender = animation.getKeyFrame(time)
  117. // load texture val texture = Texture(Gdx.files.internal("texture.png")) val split =

    TextureRegion.split(texture, 128, 128) // select frames val frames = Array<TextureRegion>() frames.add(split[0][0]) frames.add(split[0][1]) frames.add(split[0][2]) frames.add(split[0][4]) // create animation val animation = Animation<TextureRegion>(100f, frames) // select frame to draw val keyToRender = animation.getKeyFrame(time)
  118. // load texture val texture = Texture(Gdx.files.internal("texture.png")) val split =

    TextureRegion.split(texture, 128, 128) // select frames val frames = Array<TextureRegion>() frames.add(split[0][0]) frames.add(split[0][1]) frames.add(split[0][2]) frames.add(split[0][4]) // create animation val animation = Animation<TextureRegion>(100f, frames) // select frame to draw val keyToRender = animation.getKeyFrame(time)
  119. // load texture val texture = Texture(Gdx.files.internal("texture.png")) val split =

    TextureRegion.split(texture, 128, 128) // select frames val frames = com.badlogic.gdx.utils.Array<TextureRegion>() frames.add(split[0][0]) frames.add(split[0][1]) frames.add(split[0][2]) frames.add(split[0][4]) // create animation val animation = Animation<TextureRegion>(100f, frames) // select frame to draw val keyToRender = animation.getKeyFrame(time) import com.badlogic.gdx.utils.Array as GdxArray
  120. // load texture val texture = Texture(Gdx.files.internal("texture.png")) val split =

    TextureRegion.split(texture, 128, 128) // select frames val frames = GdxArray<TextureRegion>() frames.add(split[0][0]) frames.add(split[0][1]) frames.add(split[0][2]) frames.add(split[0][4]) // create animation val animation = Animation<TextureRegion>(100f, frames) // select frame to draw val keyToRender = animation.getKeyFrame(time)
  121. // load texture val texture = Texture(Gdx.files.internal("texture.png")) val split =

    TextureRegion.split(texture, 128, 128) // select frames val frames = GdxArray<TextureRegion>() frames.add(split[0][0]) frames.add(split[0][1]) frames.add(split[0][2]) frames.add(split[0][4]) // create animation val animation = Animation<TextureRegion>(100f, frames) // select frame to draw val keyToRender = animation.getKeyFrame(time) Duration per frame
  122. 100ms 100ms 100ms 100ms

  123. 800ms 100ms 100ms 100ms 100ms 100ms 100ms 100ms 100ms 100ms

    100ms
  124. Loading…

  125. val assetsManager = AssetManager() assetsManager.load("player.png", Texture::class.java) assetsManager.load("sfx/beat_intro.ogg", Music::class.java) assetsManager.load("krungthep2.fnt", BitmapFont::class.java)

    assetsManager.load("sheets/intro", Aseprite::class.java) // call it until it's loaded val isLoaded = assetsManager.update() val texture = assetsManager.get("player.png", Texture::class.java)
  126. val assetsManager = AssetManager() assetsManager.load("player.png", Texture::class.java) assetsManager.load("sfx/beat_intro.ogg", Music::class.java) assetsManager.load("krungthep2.fnt", BitmapFont::class.java)

    assetsManager.load("sheets/intro", Aseprite::class.java) // call it until it's loaded val isLoaded = assetsManager.update() val texture = assetsManager.get("player.png", Texture::class.java)
  127. val assetsManager = AssetManager() assetsManager.load("player.png", Texture::class.java) assetsManager.load("sfx/beat_intro.ogg", Music::class.java) assetsManager.load("krungthep2.fnt", BitmapFont::class.java)

    assetsManager.load("sheets/intro", Aseprite::class.java) // call it until it's loaded val isLoaded = assetsManager.update() val texture = assetsManager.get("player.png", Texture::class.java)
  128. val assetsManager = AssetManager() assetsManager.load("player.png", Texture::class.java) assetsManager.load("sfx/beat_intro.ogg", Music::class.java) assetsManager.load("krungthep2.fnt", BitmapFont::class.java)

    assetsManager.load("sheets/intro", Aseprite::class.java) // call it until it's loaded val isLoaded = assetsManager.update() val texture = assetsManager.get("player.png", Texture::class.java)
  129. val assetsManager = AssetManager() assetsManager.load("player.png", Texture::class.java) assetsManager.load("sfx/beat_intro.ogg", Music::class.java) assetsManager.load("krungthep2.fnt", BitmapFont::class.java)

    assetsManager.load("sheets/intro", Aseprite::class.java) // call it until it's loaded val isLoaded = assetsManager.update() val texture = assetsManager.get("player.png", Texture::class.java) Call it in the render method
  130. val assetsManager = AssetManager() assetsManager.load("player.png", Texture::class.java) assetsManager.load("sfx/beat_intro.ogg", Music::class.java) assetsManager.load("krungthep2.fnt", BitmapFont::class.java)

    assetsManager.load("sheets/intro", Aseprite::class.java) // call it until it's loaded val isLoaded = assetsManager.update() val texture = assetsManager.get("player.png", Texture::class.java)
  131. val assetsManager = AssetManager() assetsManager.load("player.png", Texture::class.java) assetsManager.load("sfx/beat_intro.ogg", Music::class.java) assetsManager.load("krungthep2.fnt", BitmapFont::class.java)

    assetsManager.load("sheets/intro", Aseprite::class.java) // call it until it's loaded val isLoaded = assetsManager.update() val texture: Texture = assetsManager["player.png"] inline operator fun <reified T> AssetManager.get(filename: String): T { return this.get(filename, T::class.java) }
  132. Scrollpane Label Button Select box

  133. val scene = verticalGroup { setFillParent(true) pad(10f) label("Hello Kotlin Night!")

    horizontalGroup { textButton("Click On Me") label("<-- here") } label("Another label...") selectBoxOf(GdxArray<String>().apply { add("value 1") add("value 2") add("value 3") }) } stage = Stage(FitViewport(screenWidth, screenHeight)) stage.addActor(scene) Hello Kotlin Night!
  134. val scene = verticalGroup { setFillParent(true) pad(10f) label("Hello Kotlin Night!")

    horizontalGroup { textButton("Click On Me") label("<-- here") } label("Another label...") selectBoxOf(GdxArray<String>().apply { add("value 1") add("value 2") add("value 3") }) } stage = Stage(FitViewport(screenWidth, screenHeight)) stage.addActor(scene) Hello Kotlin Night!
  135. val scene = verticalGroup { setFillParent(true) pad(10f) label("Hello Kotlin Night!")

    horizontalGroup { textButton("Click On Me") label("<-- here") } label("Another label...") selectBoxOf(GdxArray<String>().apply { add("value 1") add("value 2") add("value 3") }) } stage = Stage(FitViewport(screenWidth, screenHeight)) stage.addActor(scene) Hello Kotlin Night!
  136. val scene = verticalGroup { setFillParent(true) pad(10f) label("Hello Kotlin Night!")

    horizontalGroup { textButton("Click On Me") label("<-- here") } label("Another label...") selectBoxOf(GdxArray<String>().apply { add("value 1") add("value 2") add("value 3") }) } stage = Stage(FitViewport(screenWidth, screenHeight)) stage.addActor(scene) Hello Kotlin Night!
  137. Entity System

  138. Position Animation Player State

  139. val player = Entity() player.add(Player())) player.add(Position(100 v2 100)) player.add(Animation("idle")) player.add(StateComponent())

    Position Animation Player State
  140. ComponentMapper<Player> player = ComponentMapper.getFor(Player.class); ComponentMapper<Position> position = ComponentMapper.getFor(Position.class); ComponentMapper<Animation> animation

    = ComponentMapper.getFor(Animation.class); ComponentMapper<StateComponent> state = ComponentMapper.getFor(StateComponent.class); ... player.get(entity).life; position.get(entity).xy; animation.get(entity).getFrame(time); state.get(entity).time; Extractor Extraction
  141. inline fun <reified T : Component> EntitySystem.get(): ComponentMapper<T> = 


    ComponentMapper.getFor(T::class.java) inline operator fun <reified T : Component> Entity.get(mapper: ComponentMapper<T>): T = 
 mapper.get(this)
  142. val player: ComponentMapper<Player> = get() val position: ComponentMapper<Position> = get()

    val animation: ComponentMapper<Animation> = get() val state: ComponentMapper<StateComponent> = get() // access to components entity[player].life entity[position].xy entity[animation].frame(time) entity[state].time
  143. val player = get<Player>() val position = get<Position>() val animation

    = get<Animation>() val state = get<StateComponent>() // access to components entity[player].life entity[position].xy entity[animation].frame(time) entity[state].time
  144. val player = get<Player>() val position = get<Position>() val animation

    = get<Animation>() val state = get<StateComponent>() // access to components entity[player].life entity[position].xy entity[animation].frame(time) entity[state].time Accessing like a map
  145. Close Open

  146. 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
  147. 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
  148. 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) } State Event Transition
  149. Pitfalls

  150. Garbage Collector Garbage Collector Garbage Collector Garbage Collecto arbage C

    Garbage STOP THE WORLD
  151. altLayers = map.layers .mapIndexed { index, layer -> index to

    layer } .filter { it.second.name.startsWith("alt_") } .map { it.first } .toIntArray() List 1 List 2 List 3 List 4 mutableList
  152. val ball = Rectangle(68f, 64f, 5f, 5f) val player =

    Rectangle(64f, 64f, 100f, 10f) // the ball hit the player? player.overlaps(ball)
  153. val pool = object : Pool<Rectangle>() { override fun newObject():

    Rectangle = Rectangle() } // ... val ball = pool.obtain().apply { set(68f, 64f, 5f, 5f) } val player = pool.obtain().apply { set(64f, 64f, 100f, 10f) } // the ball hit the player? player.overlaps(ball) pool.free(ball) pool.free(player)
  154. val pool = object : Pool<Rectangle>() { override fun newObject():

    Rectangle = Rectangle() } // ... val ball = pool.obtain().apply { set(68f, 64f, 5f, 5f) } val player = pool.obtain().apply { set(64f, 64f, 100f, 10f) } // the ball hit the player? player.overlaps(ball) pool.free(ball) pool.free(player)
  155. val pool = object : Pool<Rectangle>() { override fun newObject():

    Rectangle = Rectangle() } // ... val ball = pool.obtain().apply { set(68f, 64f, 5f, 5f) } val player = pool.obtain().apply { set(64f, 64f, 100f, 10f) } // the ball hit the player? player.overlaps(ball) pool.free(ball) pool.free(player)
  156. val pool = object : Pool<Rectangle>() { override fun newObject():

    Rectangle = Rectangle() } // ... val ball = pool.obtain().apply { set(68f, 64f, 5f, 5f) } val player = pool.obtain().apply { set(64f, 64f, 100f, 10f) } // the ball hit the player? player.overlaps(ball) pool.free(ball) pool.free(player)
  157. Integration with other tools

  158. None
  159. None
  160. None
  161. None
  162. None
  163. // can be loaded using AssetManager too val tmxMap =

    TmxMapLoader().load(mapName) tmxMap.layers["bricks"]?.objects?.forEach { brick -> // create game entity } mapRenderer = OrthogonalTiledMapRenderer(tmxMap) // render method mapRenderer.setView(viewport.camera as OrthographicCamera) mapRenderer.render()
  164. // can be loaded using AssetManager too val tmxMap =

    TmxMapLoader().load(mapName) tmxMap.layers["bricks"]?.objects?.forEach { brick -> // create game entity } mapRenderer = OrthogonalTiledMapRenderer(tmxMap) // render method mapRenderer.setView(viewport.camera as OrthographicCamera) mapRenderer.render()
  165. // can be loaded using AssetManager too val tmxMap =

    TmxMapLoader().load(mapName) tmxMap.layers["bricks"]?.objects?.forEach { brick -> // create game entity } mapRenderer = OrthogonalTiledMapRenderer(tmxMap) // render method mapRenderer.setView(viewport.camera as OrthographicCamera) mapRenderer.render()
  166. // can be loaded using AssetManager too val tmxMap =

    TmxMapLoader().load(mapName) tmxMap.layers["bricks"]?.objects?.forEach { brick -> // create game entity } mapRenderer = OrthogonalTiledMapRenderer(tmxMap) // render method mapRenderer.setView(viewport.camera as OrthographicCamera) mapRenderer.render()
  167. None
  168. hit 4 sound chicken.wav

  169. tmxMap.layers["bricks"].objects.forEach { brick -> val hit: Any = brick.properties["hit"] }

    Error prone Error prone
  170. class BrickProperties(properties: MapProperties) { val x: Double by properties val

    y: Double by properties val hit: Int by properties val sound: String by properties } tmxMap.layers["bricks"].objects.forEach { brick -> val props = BrickProperties(brick.properties) val hit = props.hit }
  171. class BrickProperties(properties: MapProperties) { val x: Double by properties val

    y: Double by properties val hit: Int by properties val sound: String by properties } tmxMap.layers["bricks"].objects.forEach { brick -> val props = BrickProperties(brick.properties) val hit = props.hit }
  172. class BrickProperties(properties: MapProperties) { val x: Double by properties val

    y: Double by properties val hit: Int by properties val sound: String by properties } tmxMap.layers["bricks"].objects.forEach { brick -> val props = BrickProperties(brick.properties) val hit = props.hit } Delegates
  173. inline operator fun <reified T> MapProperties.getValue(thisRef: Any?, property: KProperty<*>): T

    { val asStr = this[property.name].toString() return when (T::class) { Double::class -> asStr.toDouble() Int::class -> asStr.toInt() Boolean::class -> "true" == asStr String::class -> asStr else -> this[property.name] } as T }
  174. val chicken: Aseprite = assets["sheets/chicken"] val idleAnimation: Animation<TextureRegion> = chicken["idle"]

  175. Json Json Json

  176. open class AsepriteTask : DefaultTask() { // ... @TaskAction fun

    export() { val exec = getExecActionFactory().newExecAction() val exts = project.extensions.getByType(AsepritePluginExtentions::class.java) val aseprite = exts.exec ?: invalideAsepritePath() // ... } private fun invalideAsepritePath(): Nothing { TODO("""Missing aseprite executable path. Please configure it using aseprite.exec property (ie: in your ~/.gradle/gradle.properties) aseprite.exec=<path to exec> or using aseprite extension in your build.gradle aseprite { exec=<path to exec> } MacOS specific : point to aseprite located into <aseprite directory>/Aseprite.app/Contents/MacOS/aseprite""") } }
  177. open class AsepriteTask : DefaultTask() { // ... @TaskAction fun

    export() { val exec = getExecActionFactory().newExecAction() val exts = project.extensions.getByType(AsepritePluginExtentions::class.java) val aseprite = exts.exec ?: invalideAsepritePath() // ... } private fun invalideAsepritePath(): Nothing { TODO("""Missing aseprite executable path. Please configure it using aseprite.exec property (ie: in your ~/.gradle/gradle.properties) aseprite.exec=<path to exec> or using aseprite extension in your build.gradle aseprite { exec=<path to exec> } MacOS specific : point to aseprite located into <aseprite directory>/Aseprite.app/Contents/MacOS/aseprite""") } } What happen if null? Encountered an error, lol!
  178. open class AsepriteTask : DefaultTask() { // ... @TaskAction fun

    export() { val exec = getExecActionFactory().newExecAction() val exts = project.extensions.getByType(AsepritePluginExtentions::class.java) val aseprite = exts.exec ?: invalideAsepritePath() // ... } private fun invalideAsepritePath(): Nothing { TODO("""Missing aseprite executable path. Please configure it using aseprite.exec property (ie: in your ~/.gradle/gradle.properties) aseprite.exec=<path to exec> or using aseprite extension in your build.gradle aseprite { exec=<path to exec> } MacOS specific : point to aseprite located into <aseprite directory>/Aseprite.app/Contents/MacOS/aseprite""") } }
  179. open class AsepriteTask : DefaultTask() { // ... @TaskAction fun

    export() { val exec = getExecActionFactory().newExecAction() val exts = project.extensions.getByType(AsepritePluginExtentions::class.java) val aseprite = exts.exec ?: invalideAsepritePath() // ... } private fun invalideAsepritePath(): Nothing { TODO("""Missing aseprite executable path. Please configure it using aseprite.exec property (ie: in your ~/.gradle/gradle.properties) aseprite.exec=<path to exec> or using aseprite extension in your build.gradle aseprite { exec=<path to exec> } MacOS specific : point to aseprite located into <aseprite directory>/Aseprite.app/Contents/MacOS/aseprite""") } }
  180. Shaders This section has nothing to do with Kotlin

  181. void main() {
 vec4 sum = vec4(0);
 
 float step

    = iResolution.y;
 // y
 for(float i = -area ; i <= area ; i += 1.) {
 // x
 for(float j = -area ; j <= area ; j += 1.) {
 float x = v_texCoords.x + i / iResolution.x;
 float y = v_texCoords.y + j / iResolution.y;
 sum += texture2D(u_texture, vec2(x, y)) * 0.005;
 }
 }
 gl_FragColor = texture2D(u_texture, v_texCoords) + sum;
 } OpenGL Shading Language (GLSL)
  182. None
  183. None
  184. None
  185. None
  186. None
  187. None
  188. None
  189. None
  190. None
  191. if (color_pixel < cutoff) { // light dark pixel =

    gl_FragColor = vec4(0.3, 0.2, 0.4., 1.0); } else { pixel = color_pixel; } 0 1 Cut off
  192. if (color_pixel < cutoff) { // light dark pixel =

    gl_FragColor = vec4(0.3, 0.2, 0.4., 1.0); } else { pixel = color_pixel; }
  193. None
  194. None
  195. None
  196. https://www.shadertoy.com/view/ld3Gz2

  197. fun makeGames()

  198. fun makeGames()

  199. @dwursteisen http://bit.ly/2poORfk

  200. Beat The High Score Game https://github.com/dwursteisen/beat-the-high-score libGDX Lib https://libgdx.badlogicgames.com/ KTX

    
 (This is NOT Android KTX) Lib https://github.com/libktx/ktx/ libGDX addons Lib https://github.com/dwursteisen/libgdx-addons/ kTerminal Lib https://github.com/heatherhaks/kterminal Game Services Lib https://github.com/MrStahlfelge/gdx-gamesvcs In Game Console
 (A la quake) Lib https://github.com/StrongJoshua/libgdx-inGameConsole Gif Recorder Lib https://github.com/Anuken/GDXGifRecorder Tiled Editor Editor https://www.mapeditor.org Aseprite Editor https://www.aseprite.org