1.
Minecraft in 500 lines of Python
Richard Donkin
@rdonkin
cloudfindhq.com

2.
github.com/fogleman/Minecraft
Early version:

3.
http://xkcd.com/353/

4.
Why Python?
Easy to write
Great community
Fast enough
Can use compilers
(Cython etc) or JIT (PyPy)
Or use a spare GPU …
Libraries, broad usage
Raspberry Pi to scientific
computing to cloud apps
http://xkcd.com/353/

5.
Pyglet
3D gaming library - pyglet.org
Simple to learn
Doesn’t mandate program structure
Wraps OpenGL
Can use py2exe / py2app
This is a quick Minecraft code walkthrough,
not a tutorial
Tutorial based on Asteroids: steveasleep.com

6.
Minecraft Essentials
Objects are blocks, in 3D grid
Operations
Move: W, S, A, D – and Tab to fly
Mouse to look (or fly)
Mouse to add or remove blocks
Textures

7.
Overview
Window class
Subclass of Pyglet window class
User interaction, movement, rendering
Model class
Models the world as blocks in 3D grid
Dictionary world[position]
where position is tuple (x, y, z)
Contains texture such as

8.
Window & Startup Code

9.
Model

10.
Look around
X axis is horizontal (look left/right)
Y axis is vertical (look up/down) – max ±90°
Only motion matters, not absolute position
Python tuple assignment

11.
Building stuff
Mouse locking, sight vector
Hit testing, block add/remove

12.
Adding a Block
Remove any existing block at (x, y, z) position from the
‘world dictionary’
Set texture for this block at position
Create or update sector (16x16 2D grid) in which this block
resides – enables speedup by only rendering some sectors
Show the block, and check if any neighbours now visible

13.
Highlighting ‘target block’
Hit-test from player position to target block
Draw line around visible edges of block, using
Pyglet

14.
1100 commits later…
github.com/boskee/Minecraft
Major fork
8,000 lines
19 contributors
Multi-player
Optionally,
compile to C via
Cython

15.
Pyglet and More
2D game toolkits:
Cocos2D: http://cocos2d.org/ - uses Pyglet
Fife: http://www.fifengine.net/ - esp. RTSs and RPGs
Add-on libraries that can work with Pyglet:
Rabbyt – sprites:
http://arcticpaint.com/projects/rabbyt/
Pymunk – physics: http://pymunk.org
Alternative frameworks:
Pygame – larger community, more game-specific, open
source book at http://inventwithpython.com/

16.
Summary
Concise, elegant code
Choose the right framework
Small games to get started
Write your own!
Try pyweek.org challenges

17.
Thank You
Richard Donkin
@rdonkin
cloudfindhq.com

18.
Sect0rization
Technique used to speed up rendering of
world – only render nearby sectors
Sector = 16x16 2D region of world
In Model, dictionary sectors[sector]
maps from sector to list of positions in that
sector
Track player position in sector
If player moves between sectors, determine
which adjacent sectors to show – see
change_sectors()