All kinds of bodies you've met until now have something in common: they are free and do not depend on each other, unless they collide. Sometimes you may want to constrain bodies to each other. If you think about Crush the Castle game, the siege machine is made by a series of bodies connected together in some way.
Box2D allows us to create constraints between bodies with joints . Joints allow us to build complex objects and give more realism to our games.
In this chapter you will learn how to create the most common types of joints, and you will discover, among other things, how to:
Pick, drag, and drop bodies with mouse joints
Keep bodies at a given distance with distance joints
Make bodies rotate using revolute joints
Give life to your games using motors
By the end of the chapter, you will be able to destroy the Angry Birds level with a siege machine.
Anyway, joints can also be used to interact with bodies, by picking and dragging them with the mouse. This is the first...