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

Preventing tunneling – setting bodies as bullets


As tunneling through static bodies isn't allowed thanks to continuous collision detection, in some cases we can also enable it on dynamic bodies by setting them as bullets. A bullet performs continuous collision detection with static and dynamic bodies.

Remember, you can experience heavy performance issues if you set all bodies to bullets, so it's up to you to find a compromise between accuracy and performance.

In my experience, I had to set as bullets only some particles and projectiles fired by players or enemies. Normally game characters do not move that fast to require them to be set as bullets.

  1. Change the Main function by adding the highlighted line:

    public function Main() {
      world=new b2World(new b2Vec2(0,5),true);
      debugDraw();
      var bodyDef:b2BodyDef=new b2BodyDef();
      bodyDef.position.Set(320/worldScale,470/worldScale);
      var polygonShape:b2PolygonShape=new b2PolygonShape();
      polygonShape.SetAsBox(320/worldScale,10/worldScale);
      var...