Exploring programming patterns through game development_Derek Briggs_Codemotion Berlin 2019

This talk will teach you about some of the programming patterns, that are commonly used in Game Development. I will be showing real world of examples, of patterns like Finite State Machine, and ECS Architecture, used in video games. I will talk about how to implement these patterns in games, why you would want to use these patterns in games, and I will talk about when to use some of these patterns, in software projects, that are not video games. I will be using Kotlin in most code samples, but knowing Kotlin, will not be required to learn something from this talk.

About:
Derek Briggs, Software-Developer, Self-Employed

I am a self taught developer. My specialties are mobile and game development. My primary languages are Kotlin/Java and Ruby. I am a Linux poweruser, and FOSS advocate.

Transcript

1. Exploring Programming Patterns Through Game Development Derek Briggs 12-13 November, 2019
2. About Me • Free and Open Source Software advocate • Hobbyist Game Developer • Website: Derekbriggs.xyz
4. What is good code? • Readable • Extendable • Simple to understand
6. What is this talk? • Programming Patterns − Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides – Gang of Four • LibGDX with Kotlin
7. What is LibGDX? • Game Framework written in Java • FOSS • Targets Android, Desktop, IOS, and HTML • Supports Kotlin with a little configuring • LibKTX – Optional 3rd party extensions
8. What is Kotlin? • JVM Language by Jetbrains • Full Interoperability with Java • Syntactically similar to Java • 2 Notable differences − Type Inference − Mutable vs Immutable “variables”
9. Type Inference Java Kotlin
10. Mutability vs Immutability Java
11. Mutability vs Immutability Kotlin Compile time error
12. tappytux/ --android/ --desktop/ --core/ ----Core.java
14. Game Loop
15. Game Loop • Essentially a giant while loop
16. Screen hide() show() render(delta : Float) pause() resume() dispose()
17. If jumpButton is pressed player jump Player Y position –= gravity Obstacle X position -= Speed If 1.5 seconds have passed spawn new obstacles If player passes an obstacle update the score
18. Update Method
19. Update Method • The responsibility of controlling entities in our games, should belong to the entities themselves
23. Game Loop and Update Method • Pros: • Separates our loop from processor speed and user input • It’s how games are made • Cons: • It’s how games are made
24. Finite State Machine
25. Finite State Machine • Define a finite set of separate and individual “States”
26. State Paused
27. Pause Playing GameOver Ready Game States
30. Ready State Inspection State Solving State
31. Java Kotlin
34. Finite State Machine • Cons: • Not always applicable
35. Data != Logic • Logic: Generally what happens in a game • Data: Exactly what happens in a game • Do not treat them as the same thing • Avoid hardcoding data whenever possible
37. TreasureChest
39. Entity Component System
40. Entity Component System
41. Player -update() -handleInput() -draw() Enemy -update() -draw()
42. Player Enemy Brick PositionComponent SpriteComponent PositionComponent SpriteComponent PositionComponent SpriteComponent VelocityComponent VelocityComponent InputComponent AIComponent
43. Player Enemy PositionComponent SpriteComponent PositionComponent SpriteComponent VelocityComponent VelocityComponent InputComponent AIComponent RenderSystem PhysicsSystem InputSystem AiSystem
44. Enemy VelocityComponent AIComponent Enemy VelocityComponent ZigZagAIComponent
47. Player SpriteComponent PositionComponent Enemy SpriteComponent PositionComponent
48. PositionComponent VelocityComponent PhysicsSystem
50. Command
51. Command • Wrap method calls as objects
57. Command • Commands are an object-oriented replacement for callbacks • Function pointers and closures are pretty closely related • Cons: • You may end up with a LOT of classes
58. Object Pool • Reuse & recycle objects, instead of creating new ones
59. Deleted Here Spawn Here
60. The End • Website: Derekbriggs.xyz • Email: Contact@derekbriggs.xyz