This document discusses game programming using the ForPlay library. It begins with an overview of the anatomy of a 2D arcade game, including the game lifecycle, asset management, and input/output subsystems. It then describes the Impact HTML5 game library and how it uses canvas and audio tags to target classic 2D games. Finally, it demonstrates how to generate a simple ForPlay project in 30 seconds using Maven, and notes that ForPlay is not limited to HTML but also supports Android, Java Desktop and Flash platforms.

1. Chrome Game programming
(with ForPlay)
Firenze GTUG, 06.07.2011
Luca Masini

2. Agenda
■ Anatomy of a 2D Arcade
■ Impact HTML5 Game Library
■ ForPlay: features
■ Hand-on a simple demo

3. Anatomy of a 2D Arcade
Game Lifecycle
We can identify three steps:
● init: asset loading and general housekeeping
● update: game logic and physics
● paint: everything that is strictly inherent to graphics

4. Anatomy of a 2D Arcade
Asset Management
● We need to load Images, Sounds, Text before they are
used, but in a smart way so that the memory is not filled
from the start.
● We also need a callback mechanism that warns us when a
particular asset is loaded.

5. Anatomy of a 2D Arcade
I/O Subsystems
● Input from joypad, touchscreen, keyboard, pointer
● Disk Storage and network
● Audio Device
● Video Device

6. Impact HTML5 Game Library
● Impact has a visual game editor for level and AI
scripting
● It really uses CANVAS and AUDIO tags
● Target at classic 2D games, using many ideas from
old consoles (like Super Nintendo)
● Sprites are drawn over multiple background layers
(for parallax) made up of many bricks of smaller
images

7. Impact: Weltmeister Game Editor

8. First ForPlay project in 30s
Using a maven-archetype:
mvn -DarchetypeRepository=
http://forplay.googlecode.com/svn/mavenrepo
-DarchetypeGroupId=forplay
-DarchetypeArtifactId=forplay-sample-archetype
-DarchetypeVersion=1.0
archetype:generate

11. ...forplay is not limited to HTML, these are the generated
platforms:
● HTML5
● Android
● Java Desktop
● Flash

12. Riferimenti
● Impact official site: http://impactjs.com/
● Impact article on Google Code Blog: http:
//googlecode.blogspot.com/2011/05/creating-2d-
games-with-javascript-html5.html
● forplay official site: http://code.google.com/p/forplay/
● Kick-ass Game Programming with GWT (Google I/O
2011): http://www.google.
com/events/io/2011/sessions/kick-ass-game-
programming-with-google-web-toolkit.html