Book Image

Box2D for Flash Games

Book Image

Box2D for Flash Games

Overview of this book

Physics games are getting more and more popular, and Box2D is the best choice if you are looking for a free, stable and robust library to handle physics. With Box2D you can create every kind of 2D physics game, only coding is not the fun part, but the game itself. "Box2D for Flash Games" will guide you through the process of making a Flash physics game starting from the bare bones and taking you by hand through complex features such as forces, joints and motors. As you are learning, your game will have more and more features, like the physics games you are used to playing. The book analyzes two of the most played physics games, and breaks them down to allow readers to build them from scratch in a step-by-step approach. By the end of the book, you will learn how to create basic primitive bodies as well as complex, compound bodies. Motors will give life to cars, catapults and siege machines firing bullets, while a complete collision management will make your game look even more realistic. If you want to make full Flash games with physics, then Box2D for Flash Games will guide you through the entire process of making a Flash physics game.
Table of Contents (15 chapters)
Box2D for Flash Games
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Physics games aren't just a matter of physics


This section has nothing to do with Box2D, and it's just necessary to allow the player to launch the bird. So I am explaining what happens here very quickly, in order to go straight to the point.

Before we start drawing, I want you to know that you can mix physics and non-physics scripts in your game, just like I am doing now. In this case, player interaction is not managed by Box2D, which comes into play once the bird is released.

First, we need some more class-level variables:

private var world:b2World;
private var worldScale:Number=30;
private var theBird:Sprite=new Sprite();
private var slingX:int=100;
private var slingY:int=250;
private var slingR:int=75;

theBird is the sprite representing the draggable bird, slingX and slingY are the coordinates of the center of the sling in pixels, and slingR is the radius of the draggable area of the sling in pixels.

Now, we need to draw some stuff on the stage. We'll draw the big circle representing the...