class WorldChild extends Component {
  //...
  render() {
    return (
      <Body
        args={[0, 384, 64, 64, { inertia: Infinity }]}
        ref={(b) => { this.body = b; }}
      >
        <MySprite/>
      </Body>
    );
  }
}

class WorldChild extends Component {
  //...
  render() {
    return (
      <Body
        args={[0, 384, 64, 64, { inertia: Infinity }]}
        ref={(b) => { this.body = b; }}
      >
        <MySprite/>
      </Body>
    );
  }
}
