anchor.diff:      double angularVelocity: 0.0,
       this.linearDampening: 0.0,
       double awakeangularDampening: 0.0,
  -    this.allowSleep: true,
  -    this.awake: true,
  -    this.fixedRotation: false,
  -    this.bullet: false,
  -    this.active: true,
  +    bool allowSleep: true,
  +    bool awake: true,
  +    bool fixedRotation: false,
  +    bool bullet: false,
  +    bool active: true,
       this.gravityScale: 1.0
     }) {
       this.density = density;
  
positive.code:     this.linearVelocity = linearVelocity;
      this.angularVelocity = angularVelocity;
      this.angularDampening = angularDampening;
    }
  
    Object tag;
  
negative.code:       _body.angularDamping = angularDampening;
    }
  
    bool _allowSleep;
  
    bool get allowSleep => _allowSleep;
  
    set allowSleep(bool allowSleep) {
      _allowSleep = allowSleep;
  
      if (_body != null)
        _body.setSleepingAllowed(allowSleep);
    }
  
    bool _awake;
  
    bool get awake {
      if (_body != null)
        return _body.isAwake();
      else
        return _awake;
    }
  
    set awake(bool awake) {
      _awake = awake;
  
      if (_body != null)
        _body.setAwake(awake);
    }
  
    bool _fixedRotation;
  
    bool get fixedRotation => _fixedRotation;
  
    set fixedRotation(bool fixedRotation) {
      _fixedRotation = fixedRotation;
  
      if (_body != null)
        _body.setFixedRotation(fixedRotation);
    }
  
    bool _bullet;
  
    bool get bullet => _bullet;
  
    set bullet(bool bullet) {
      _bullet = bullet;
  
      if (_body != null) {
        _body.setBullet(bullet);
      }
    }
  
    bool _active;
  
    bool get active {
      if (_body != null)
        return _body.isActive();
      else
        return _active;
    }
  
    set active(bool active) {
      _active = active;
  
      if (_body != null)
        _body.setActive(active);
    }
  
    double gravityScale;
  
  