Factories and Definitions

To create a Body or a Joint, you need to call the factory functions on World:

body = world.createBody(bodyDef);
joint = world.createJoint(jointDef);

And there are corresponding destruction functions:

world.destroyBody(body)
world.destroyJoint(joint)

When you create a body or joint, you need to provide a definition. These definitions contain all the information needed to build the body or joint. By using this approach we can prevent construction errors, keep the number of function parameters small, provide sensible defaults, and reduce the number of accessors.

Since fixtures must be parented to a body, they are created and destroyed using a factory method on Body:

let fixture = body.createFixture(fixtureDef);
body.destroyFixture(fixture);

There is also a shortcut to create a fixture directly from the shape and density.

let fixture = body.createFixture(shape, density);