code: function ( tracker, gPoint ) {
              var guid = _generateGuid( tracker, gPoint );
  
              trackerPoints.push(
                  {
                      guid: guid,
                      gPoint: gPoint,
                      lastPos: gPoint.currentPos
                  } );
  
              // Only fire up the interval timer when there's gesture pointers to track
              if ( trackerPoints.length === 1 ) {
                  lastTime = $.now();
                  intervalId = window.setInterval( _doTracking, 50 );
              }
          }
docs: Public. Add a gesture point to be tracked