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
About the Author
About the Reviewers

Creating an oriented box shape

To create an oriented box shape, we will use a b2PolygonShape method similar to SetAsBox, yet more advanced and called the SetAsOrientedBox method.

The arguments are the width and height of the box, the center of the box, also defined as a b2Vec2 object, and the rotation in radians.

  1. Applying this concept, the idol function continues in the following way:

    var bW:Number=5/worldScale;
    var bH:Number=20/worldScale;
    var boxPos:b2Vec2=new b2Vec2(0,10/worldScale);
    var boxAngle:Number=- Math.PI/4;

    The first two lines are quite understandable as we are defining the size of the box, which is same as the box we just created.

    Looking at the third line, where I define the position, you could have some doubts. The center of the body of the first idol box was (320,242) in pixels, so why am I placing the second idol box at (0,10)? Shouldn't it be placed near to the first idol box?

    That's the magic of compound objects you are about to learn. Now we aren't defining the position as...