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!

(11 September 2019 - Oslo - JavaZone 2019)
Video: https://vimeo.com/362771304

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 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 lightning strikes you!
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
15. John Carmack
19. Game 
 development Kotlin libGDX
20. You, at the end of 
 this conference Game 
 development Kotlin libGDX
21. Game Development?
27. public void render(float delta) {
 movePlayer(delta);
 moveEnemies(delta);
 moveWorld(delta);
 
 renderWorld();
 renderEnemies();
 renderPlayer();
 }
28. public void render(float delta) {
 movePlayer(delta);
 moveEnemies(delta);
 moveWorld(delta);
 
 renderWorld();
 renderEnemies();
 renderPlayer();
 }
29. public void render(float delta) {
 movePlayer(delta);
 moveEnemies(delta);
 moveWorld(delta);
 
 renderWorld();
 renderEnemies();
 renderPlayer();
 }
30. public void render(float delta) {
 movePlayer(delta);
 moveEnemies(delta);
 moveWorld(delta);
 
 renderWorld();
 renderEnemies();
 renderPlayer();
 } 60x
 seconds
31. (0,0) x y
32. Why libGDX?
34. ❤
35. Pavel Quest Destroy Blocks Mirage Realms
37. Hair Dash - http://cleancutgames.com/
39. Bob & Prickle - http://www.crealodegames.com/
41. Let’s make a game!
44. Core iOS GWT Android Desktop
45. void render(float delta) { }
46. fun render(delta: float) { }
47. class HelloScreen : ScreenAdapter() { override fun render(delta: Float) { } }
48. class HelloScreen : ScreenAdapter() { override fun render(delta: Float) { Gdx.gl.glClearColor(0f, 0f, 0f, 1f) Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT) } }
49. class HelloScreen : ScreenAdapter() { private val shape = ShapeRenderer() override fun render(delta: Float) { Gdx.gl.glClearColor(0f, 0f, 0f, 1f) Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT) } }
50. class HelloScreen : ScreenAdapter() { private val shape = ShapeRenderer() override fun render(delta: Float) { Gdx.gl.glClearColor(0f, 0f, 0f, 1f) Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT) shape.begin(ShapeRenderer.ShapeType.Filled) shape.end() } }
51. class HelloScreen : ScreenAdapter() { private val shape = ShapeRenderer() override fun render(delta: Float) { Gdx.gl.glClearColor(0f, 0f, 0f, 1f) Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT) shape.begin(ShapeRenderer.ShapeType.Filled) shape.color = Color.RED shape.circle(0f, 0f, 20f) shape.end() } }
54. class HelloScreen : ScreenAdapter() { override fun render(delta: Float) { Gdx.gl.glClearColor(0f, 0f, 0f, 1f) Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT) } }
55. class HelloScreen : ScreenAdapter() { private val batch = SpriteBatch() override fun render(delta: Float) { Gdx.gl.glClearColor(0f, 0f, 0f, 1f) Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT) } }
56. class HelloScreen : ScreenAdapter() { private val batch = SpriteBatch() private val texture = Texture("badlogic.jpg") override fun render(delta: Float) { Gdx.gl.glClearColor(0f, 0f, 0f, 1f) Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT) } }
57. class HelloScreen : ScreenAdapter() { private val batch = SpriteBatch() private val texture = Texture("badlogic.jpg") override fun render(delta: Float) { Gdx.gl.glClearColor(0f, 0f, 0f, 1f) Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT) batch.begin() batch.end() } }
58. class HelloScreen : ScreenAdapter() { private val batch = SpriteBatch() private val texture = Texture("badlogic.jpg") override fun render(delta: Float) { Gdx.gl.glClearColor(0f, 0f, 0f, 1f) Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT) batch.begin() batch.draw(texture, 0f, 0f) batch.end() } }
59. Position = (0, 0) Position = (10, 0) Position = (0, -5) Position = (-10, 5)
60. class MyScreen : ScreenAdapter() { private val batch = ShapeRenderer() private val position: Vector2 = Vector2(0f, 0f) 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() } }
61. class MyScreen : ScreenAdapter() { private val batch = ShapeRenderer() private val position: Vector2 = Vector2(0f, 0f) 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() } }
62. class MyScreen : ScreenAdapter() { private val batch = ShapeRenderer() private val position: Vector2 = Vector2(0f, 0f) 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() } }
63. class MyScreen : ScreenAdapter() { private val batch = ShapeRenderer() private val position: Vector2 = Vector2(0f, 0f) 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() } }
64. class MyScreen : ScreenAdapter() { private val batch = ShapeRenderer() private val position: Vector2 = Vector2(0f, 0f) override fun render(delta: Float) { position.add(0f, -0.5f) val (x, y) = position batch.begin(ShapeRenderer.ShapeType.Filled) batch.color = Color.CHARTREUSE batch.circle(x, y, radius) batch.end() } }
65. /** * 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
66. /** * 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)
67. 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)
68. entity.add(Ball()) .add(Position(Vector2(-100f, -100f))) .add(Size(Vector2(8f, 9f))) .add(Offset(Vector2(4f, 4f)))
69. entity.add(Ball()) .add(Position(Vector2(-100f, -100f))) .add(Size(Vector2(8f, 9f))) .add(Offset(Vector2(4f, 4f)))
70. entity.add(Ball()) .add(Position(-100 v2 -100f)) .add(Size(8 v2 9)) .add(Offset(4 v2 4)) Create a 
 new Vector2 infix fun Number.v2(other: Number): Vector2 { return Vector2(this.toFloat(), other.toFloat()) }
71. Collision engine
73. Side Racket 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. val ball = Rectangle(68f, 64f, 5f, 5f) val player = Rectangle(64f, 64f, 100f, 10f) // the ball hit the player? player.overlaps(ball)
76. val ball = Rectangle(68f, 64f, 5f, 5f) val player = Rectangle(64f, 64f, 100f, 10f) // the ball hit the player? player.overlaps(ball) (Simple AABB Engine)
80. Box2D
81. var world = World(Vector2(0, -10), true) // ... 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) // ... 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
83. var world = World(Vector2(0, -10), true) // ... 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 »
84. var world = World(Vector2(0, -10), true) // ... 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() Attach data from your world to Box2D world
85. var world = World(Vector2(0, -10), true) // ... 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. var world = World(Vector2(0, -10), true) // ... 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()
87. Traversable
88. The ball and boxes use 
 AABB Physic Engine Wreckages use 
 Box2D Physic Engine
89. Animations
92. // 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)
93. // 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)
94. // 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)
95. // 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
96. // 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)
97. // 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
98. 100ms 100ms 100ms 100ms
99. 800ms 100ms 100ms 100ms 100ms 100ms 100ms 100ms 100ms 100ms 100ms
100. y = Interpolation.bounceOut.apply(time) * 100f Non linear Should be a percentage (0..1) y will go from 0 to 100
102. Linear Bounce Elastic Pow2
103. Field Of View
105. 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()
106. 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
107. 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
108. viewport.camera.rotate(10f, 0f, 0f, 1f)
113. Our world
 (Orientation: Portrait)
114. ScreenViewport
115. StretchViewport
116. FitViewport Clear this zone Clear this zone
117. FillViewport
118. ExtendViewport Displaying this zone
119. 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) } }
120. 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
121. 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) } }
122. Around the game
123. 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:$console" }
124. dependencies { compile "com.badlogicgames.gdx:gdx:$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" }
125. 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:$console" }
126. dependencies { compile "com.badlogicgames.gdx:gdx:$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" }
127. 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" }
128. Entities & Ashley
130. Entity Player Monster Knight Ghoul
131. Composition 
 over 
 Inheritance
132. Position Animation Player State Entity
133. val player = Entity() player.add(Player())) player.add(Position(100 v2 100)) player.add(Animation("idle")) player.add(StateComponent()) Position Animation Player State
134. 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
135. 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)
136. 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
137. 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
138. 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
139. 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)
140. Close Open
141. 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
142. 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
143. 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
144. Loading…
145. 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)
146. 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)
147. 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)
148. 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)
149. 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
150. 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)
151. 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) }
152. Integration with other tools
158. // 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()
159. // 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()
160. // 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()
161. // 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. hit 4 sound chicken.wav
164. tmxMap.layers["bricks"].objects.forEach { brick -> val hit: Any = brick.properties["hit"] } Error prone Error prone
165. 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 }
166. 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 }
167. 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
168. 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 }
169. val chicken: Aseprite = assets["sheets/chicken"] val idleAnimation: Animation<TextureRegion> = chicken["idle"] Inverser slides. Je veux accéder aux animations -> export des metas -> méthode d'extensions. 
 -> explication j'ai fais un plugin qui fait ça pour moi.
170. Json Json Json
171. 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""") } }
172. 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!
173. 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""") } }
174. 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""") } }
175. Screens
176. Scrollpane Label Button Select box
177. val scene = verticalGroup { setFillParent(true) pad(10f) label("Hello JavaZone!") 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 JavaZone!
178. val scene = verticalGroup { setFillParent(true) pad(10f) label("Hello JavaZone!") 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 JavaZone!
179. val scene = verticalGroup { setFillParent(true) pad(10f) label("Hello JavaZone!") 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 JavaZone!
180. val scene = verticalGroup { setFillParent(true) pad(10f) label("Hello JavaZone!") 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 JavaZone!
181. Game screen screen screen screen screen
182. 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) } } }
183. 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 ⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠⚠
184. Pitfalls
185. Garbage Collector Garbage Collector Garbage Collector Garbage Collecto arbage C Garbage STOP THE WORLD
186. 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
187. val ball = Rectangle(68f, 64f, 5f, 5f) val player = Rectangle(64f, 64f, 100f, 10f) // the ball hit the player? player.overlaps(ball)
188. 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)
189. 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)
190. 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)
191. 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)
192. Shaders This section has nothing to do with Kotlin
193. 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)
203. 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
204. if (color_pixel < cutoff) { // light dark pixel = gl_FragColor = vec4(0.3, 0.2, 0.4., 1.0); } else { pixel = color_pixel; }
208. https://www.shadertoy.com/view/ld3Gz2
209. fun makeGames()
210. fun makeGames()
211. 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
212. 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
213. @dwursteisen http://bit.ly/2poORfk