code: function( options ){
      
                  var self = this;
                  this._pos = new Physics.vector();
                  // call parent init method
                  parent.init.call( this );
                  this.options.defaults( defaults );
                  this.options.onChange(function( opts ){
                      self._maxDist = opts.max === false ? Infinity : opts.max;
                      self._minDist = opts.min ? opts.min : 10;
                      self.position( opts.pos );
                  });
                  this.options( options );
              }
docs: extended