Who am I?

• Software Developer @ Points
  • Develop eCommerce platform for Loyalty Programs
  • Dockerized Flask REST API microservices
• Open Source
  • Rookeries - CMS for developers & designers 
  • Contributor to Fabric, Ansible & core Python
• Board gamer → Video gamer → Developer
  • Apparently too late to the wargaming scene.
  • Started programming from copying/porting
    Apple 2 Basic games to Microsoft QBasic.
  • First open source project was a game: justCheckers.

Building a Game in Kivy @ PyCon

• Day 1 - Sprinting on Flask
• Day 2-4 - Kivy Game Camp sprinting.
  • Because making a game is more fun, than
    submitting PRs for a web framework...
  • Hosted by Amy & Kjell Woodling from
    Leap, Learn, Fly!
  • Improved Game Camp and Kivy documentation.

PyQt / PySide

• PySide / PyQt
  • Python bindings for C++ based on Qt framework.
  • Powerful screen + widget managements.
  • Need C++ experience to effectively use.
• PyOtherside - QML bindings for Python.

PyGTK, Pyglet, PyGame, etc.

• PyGTK
  • Python bindings for C based GTK.
• PyGame
  • Bindings for SDL, more low-level.
• Pyglet
  • OpenGL based scene-graph library.
• Electron
  • Javascript frontend.
  • Can use Python backend.
• Tcl

Kivy

• Pythonic!
• Flexible due to OpenGL rendering.
• Event loop is good for games and
  interactive apps. 
• UI layout with declarative KV
  (Classic widget + layout container).
• Reasonable cross-platform build setup.

Kivy Basics

• Standard UI widget / layout based.
  • Widgets encapsulate behaviour and look.
  • Layout (with nesting) to position widgets.
• Use of KV language to declare the UI.
  • Can mix Python and KV.
• Standard event loop to update the screen.
  • Nothing drawn outside of the event loop.

KV Example

Hexagon Layouts

• Standard Layouts:
  • Grid
  • Box
  • Float (free floating absolute positioning)
• No such thing as a Hexagon Grid layout. :(  
  Gotta build your own.
• Lots of math involved:
  • Positioning hexes together.
  • Adding map positional coordinates.
  • Using a cubic coordinates for movement and distance.
  • Thankfully Amy & Kjell are mathematicians. :)

Map Building

Unit Control via Events

• Having the ability to select and control a unit.
  • Give it commands (like move or attack).
• Kivy has a rich input event system:
  • Multiple touch events out of the box.
  • Each Widget can has hooks for on_EVENT().
    • e.g. on_touch_down(), on_pressed()
  • Events broadcast from parent to children.
  • Can create and use custom events.

Kivy Gotchas

• Three different phases for running painting
  instruction on a canvas.
  • before, during and after initialization.
• Kivy allows for changeable window sizes.
  • Need to be aware of positioning in a
    dynamic manner.
• Events don't propagate unless you return true,
  in the event handler method.

Targetting Desktops with PyInstaller

• PyInstaller is NOT an installer.
• PyInstaller is a bundler for Python modules
  + libraries.
  • Single directory mode
  • Single binary mode (runnable zip archive)
• Relatively straight forward with "recipes" for Kivy.
• Works for all desktop OS: Windows, Linux, OS X.

How about mobile devices?

• Kivy project: python-for-android
  • Deals with bundling of an app into an APK.
• Use Buildozer for building apps:
  • Automates lot of the setup and linking.
  • Three easy steps:
    1. buildozer init
    2. Edit the spec file
    3. buildozer android debug deploy
    4. Debug/fix when things break
  • Works with iOS and Android.

Building Game Engines +
Map Editors

• Real game devs usually don't build game engines.
  • Game engines can be time intensive and complex.
  • Standard use of third-party engines.
• Use a entity-component architecture.
  • Every on-screen entity is made of a bunch of
    self-contained components.
• Use a tile or map editor.

KivEnt + Tiled

• KivEnt: entity-component game engine for Kivy​
  • Similar to Unity3d conceptually.
• Tiled map editor support
  • Recent support for hex-based layouts from Tiled in KivEnt
    (Thanks to Google Summer of Code contrib)

Aftermath

• Kivy makes game development possible and easy.
  • App development in general in Python.
• Game dev means lots and lots of math and tweaking.
  • Experiment, run, tweak, run, repeat.
• Use KivEnt for more serious game dev.
• Cross-platform app / game development possible
  in Python with Kivy.