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!

Code: https://github.com/dwursteisen/beat-the-high-score
Game: https://play.google.com/store/apps/details?id=com.github.dwursteisen.beat
Video: https://www.youtube.com/watch?v=kDxerDYelLs

(KotlinConf 2018 - 4th October 2018 - Amsterdam)

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.
5. -Gilles Allain In a mighty move, he stole all the chickens of the farm...
7. -Gilles Allain those chickens were our...friends.
8. -Gilles Allain the same night, a thunder strikes you!
10. -Gilles Allain ...this strike have given you powers to bring back... ...our friends!
11. David Wursteisen
14. John Carmack
17. Rota Pong
18. Wiz 
 The Wizard
19. Beat 
 The High 
 Score
20. Game engines
22. ❤
23. Pavel Quest Destroy Blocks Mirage Realms
24. Hair Dash - http://cleancutgames.com/
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
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
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)
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
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 ⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠
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) } }
103. ScreenViewport
104. StretchViewport
105. FitViewport Clear this zone Clear this zone
106. FillViewport
107. ExtendViewport Displaying this zone
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
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 KotlinConf!") 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)
134. val scene = verticalGroup { setFillParent(true) pad(10f) label("Hello KotlinConf!") 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)
135. val scene = verticalGroup { setFillParent(true) pad(10f) label("Hello KotlinConf!") 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)
136. val scene = verticalGroup { setFillParent(true) pad(10f) label("Hello KotlinConf!") 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)
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: 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 Accessing like a map
144. Close Open
145. 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
146. 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
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) } State Event Transition
148. Pitfalls
149. Garbage Collector Garbage Collector Garbage Collector Garbage Collecto arbage C Garbage STOP THE WORLD
150. 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
151. val ball = Rectangle(68f, 64f, 5f, 5f) val player = Rectangle(64f, 64f, 100f, 10f) // the ball hit the player? player.overlaps(ball)
152. 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)
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. Integration with other tools
162. // 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()
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()
167. hit 4 sound chicken.wav
168. tmxMap.layers["bricks"].objects.forEach { brick -> val hit: Any = brick.properties["hit"] } Error prone Error prone
169. 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 }
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 } Delegates
172. 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 }
173. val chicken: Aseprite = assets["sheets/chicken"] val idleAnimation: Animation<TextureRegion> = chicken["idle"]
174. Json Json Json
175. 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""") } }
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""") } } What happens if null? Encountered an error, lol!
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""") } }
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. Shaders
180. 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)
190. 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
191. if (color_pixel < cutoff) { // light dark pixel = gl_FragColor = vec4(0.3, 0.2, 0.4., 1.0); } else { pixel = color_pixel; }
195. https://www.shadertoy.com/view/ld3Gz2
196. fun makeGames()
197. fun makeGames()
198. @dwursteisen http://bit.ly/2poORfk
199. 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