1. Teaching with Greenfoot
For teachers of ICS3U/4u

2. NOTE TO TEACHERS
Everything you see here (these slides, code samples, programs) are on your complimentary USB drive.

3. Agenda Intro – What is Greenfoot (5 minutes)
Greenfoot Basics – (15 minutes)
First look at Greenfoot – Creating a World and Actors
Basic Concept Demo
Important Elements of a good scenario
Hands On Part 1 (20 minutes)
Create your World, your Actor and create movement
Collision Detection Tutorial (10 minutes)
Detect Objects colliding and triggering events
Adding Sound
Hands On Part 2 (remaining time…)

4. What is greenfoot? Greenfoot is:
A simple yet useful Java IDE similar to BlueJ
An easy-to-use 2D graphics engine
An object based programming tool that allows for easy demonstration and instruction of object oriented programming through visual examples
Easy to learn for any experienced Java programmer

5. Why Greenfoot?
Java is a great academic language – it’s strict structure and object oriented nature makes it ideal for UCS3U/4U
However, Java has an antiquated, tedious set of graphics commands.
Students quickly tire of text-only programming in Java, and often struggle with Java’s built in graphics
Greenfoot provides an easier approach to creating games and visual simulations

6. Getting started
Greenfoot is available for Mac OSX, Windows and Linux – (Java must be installed)
Can easily be installed by your TST
If it is not possible to have it installed, there is a Windows-only “Greenfoot on a Stick” version that can be run from a USB key – which is what we will be working with today

7. Pros and cons
PROS
CONS
Easy to start programming games and simulations complete with 2D graphics and sound
Mouse support
Extensible with the full Java programming language
Makes for fun tasks and assignments
Effective way to teach and demonstrate OOP
Poor support for text(although you can use the System console)
No 3D
Ultimately limited to games of moderate complexity
Must use included IDE

8. Some additional benefits
Good for teaching Linked Lists – some Greenfoot methods return a linked list of objects
Useful for teaching inheritance – all sub-classes of Actors can be further inherited from, leaving the potential to create and use different super classes to good effect
Grade 11 students can usually have basic functionality of some sort working within 1 period
Module available for XBox360 Kinect module – It is possible to use Greenfoot to program for body motion capture! (although I haven’t tried…)

9. Greenfoot Resources
The development staff of Greenfoot is active in creating a plethora of resources on an on-going basis, including:
The Greenroom – Discussion forum and resources for teachers, requires registration from teacher address -
Numerous online resources for learning Greenfoot -
Scenario (and code) sharing -
Discussion Forum for students –
And more…

10. First look at Greenfoot
IDE, Actor and World creation Tutorial

11. Actor
All objects that will move within the game world should be sub-classes of Actor
(It is possible to create non-Actor classes within Greenfoot – useful for advanced projects)
You can declare abstract sub-classes of Actor and then create sub-sub-classes – useful for creating related types of objects (I.e. different enemies in a game)

12. World
Your program begins by you creating a sub-class of World – defining your own game world
Typically, the World will own the Actors.
Includes a number of global variables – world size, act() order, state of execution (is the game currently running), etc.

13. Persistent Actors
In many programs, you will want to keep a permanent reference to your Actors
This is best accomplished by defining your Actors within the constructor of your World class
Your World can contain methods that allow Actors to communicate

14. Persistent Actor
DEMo

15. The “main” method No main() method in Greenfoot
The scenarios are run in “acts” where the act() method of every class gets called once per frame
Use your World (the class you created which inherits from World, not World itself) as you would a main method.
You can add an act() method to your World (and you should!)

16. Building your World
Some things that you should consider for your World:
setPaintOrder() – allows you to control which Actors are displayed on top and which will appear behind
setActOrder() – set the order in which classes’ act() methods get called in each act.
Store permanent references to Actors which you will need to manage later
Instance variables for your data and for program flow

17. Your first game! Frogger Game!
Little Frogger must cross the road without getting smushed
Example solutions (basic and advanced) on your USB key

18. Process Part 1 – Create the basic objects
A World with a background image
A little Frogger Actor that takes input from the keyboard
Cars (or other Enemies) (Actors) that cross the road and threaten to kill our poor frog!
Part 2 – Add collision detection and associated actions
Part 3 – Finishing Touches, polish, as time allows
Sounds
Displaying Text (score, level, etc)

19. Various Resources
Greenfoot on a Stick – Greenfoot and all associated Java libraries, runnable off of a USB key
Paint.net – best free paint program I’ve been able to find. Does transparency.
Frogger! (my 3-4 hours of coding version)
A few other scenarios