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http://www.egeniq.com
[email protected]
@egeniq
Dutch PHP Conference, 7 June 2013
Ivo Jansch
Cheater’s Math
Or: how iOS app + PHP == $$$
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About Me
@ijansch
Entreprenerd
Mobile & Web Developer
Author & Speaker
Talk feedback:
http://joind.in/8446
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2 ways to make money
‣Successful games
‣Cheats for successful games
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The arrival of Letterpress
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Beating Letterpress
‣What do we need:
• Analyze screen (dimensions, location of the board)
• OCR
• Color matching
• Word matching
• Word scoring
• Game strategy
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OCR
‣Complex algorithms
‣Look at existing libraries
‣Image comparison
or.....
‣CHEAT!
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Fast & Dumb Binary Tree Pixel Thingee
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ABCDEFGIJOPQRSTZ HKLMNUVWXY
BDEFPRTZ ACGIJOQS HMNXY KLUVW
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Workable, but crude & ugly code
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Same for dimensional stuff
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Heuristic scoring
‣Simple rules
‣Strategy design pattern
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GameCoach was born
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The Problem
‣T=0: Letterpress came out
‣T=5: Idea for coaching app
• No cheat apps available
‣T=10: GameCoach for Letterpress ready
• 1 other cheat app available
‣T=17: Apple approved GameCoach
• 23 other cheat apps available :-(
• By now there are over 40
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GameCoach for Letterpress retrospective
‣ Few downloads per day, even fewer buys
• Letterpress themes weren’t supported
• Buggy OCR
• Average: $ 0.18 / day
• Did we care? No, we had fun!
‣ To make $$$ with apps like this, we need to:
• Reduce the amount of code we need to write
• Support more & other games
• Release quickly
• So abstract and generalize the hell out of the time consuming
parts!
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GameCoach new style
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Game management,
analysis
Signatures Generic parser,
game strategy
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Generalizing a data model
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Game
Variant
Theme Theme
Tags
TileTell
#dd0000=theirs
#ff0000=theirs,locked
#0000dd=mine
#000000=char
Theme
Tell
name=letterpress
board=5x5
ipad
iphone
10,10=theirs,mine,locked
tolerance=3 240,50
400,50
Classic
Disco
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Recursive dimension parsing
board width = screen width
board height = screen width (square board)
board x = 0
board y = screen height - board height
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Poor Man’s OCR
‣Pixel method worked, but hard to do
‣What if we train a parser using existing
screenshots?
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Enter The Matrix
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Enter The Matrix
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How? Just some Imagick
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Canonicalize the screenshots
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Reduced Matrix
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Reduced Matrix up close
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Finally, combine matrixes into OCR tree
Creating the tree is remarkably simple:
findTellPixel: find the ‘most binary’ pixel;
dividing the set of letters in 2 halves.
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Result: generic signatures
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Client side generic parser
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+
=
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We need a CMS!
‣ZF? Symfony?
‣Nah, let’s go for good old ATK
• http://www.atk-framework.com
• 13 years old, but gets the job done
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Stop!
Demo Time!
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CSS Sprite techniques
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Issue: css sprites &
image scaling != friends
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CSS sprite techniques
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(yes I know inline styles are evil)
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HTML5 Canvas (Yay!)
‣It’s so easy, even you can use it.
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HTML5 Canvas
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Reading canvases
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Writing canvases
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GameCoach engine to the test: Ruzzle
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Ruzzle Retrospective
‣GameCoach for Letterpress: 5 days
‣GameCoach for Ruzzle: 5 hours
• Required support for more tile properties (e.g. inter-tile
margin)
• Different word search (using ‘Trie’ algorithm: http://
en.wikipedia.org/wiki/Trie)
• Multiple dictionary support
• Some rendering changes
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Next step: WordOn!
‣WordOn was piece of cake
• Playing /collecting screenshots was the time consuming
part
‣GameCoach was first (and still only) cheat
‣Reached Nr. 6 top grossing in word games :-)
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The future :-)
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The future :-)
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Summary
‣Development reduction by PHP backend:
zillion percent
‣Managed to incorporate everything I ever
learned:
• Database design, Design patterns, Image manipulation,
CSS sprites, CMS systems, Math, File uploads, JSON, APIs,
Imagick, command line PHP, memory management,
internationalization, caching
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Thank you! Questions?
http://www.egeniq.com
[email protected]
@egeniq
http://www.egeniq.com
[email protected]
@ijansch