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

Chapter 5. Handling Collisions

Given a Box2D world and some moving bodies, sooner or later two of them will collide. Physics games rely on collisions for most gameplay features. When a bird smashes pig's castle in Angry Birds, it is thanks to collisions; when the idol falls down the totem and breaks on the ground, that's due to collisions.

Box2D already does all the required tasks to solve collisions and run the simulation without any coding on our part. By the way, in some situations, we need to interact with collisions for a gameplay purpose.

Think about Angry Birds, hitting hard on a wooden wall will break it, but normal Box2D collision routines do not manage wooden wall breaking. Moreover, if the Totem Destroyer idol hits the ground, the level fails but again Box2D just manages the collisions without caring about the gameplay rules.

That's why sometimes we need to analyze collisions, and luckily Box2D allows us to do it thanks to contacts: objects created by Box2D to manage collisions between...