map.js

gmap.drawPolyline({
      path: [[lat, lng], [lat, lng]],
      icons: [{
        icon: {
          //path: google.maps.SymbolPath.BACKWARD_OPEN_ARROW,
          //scale: 15,
          path: 'M 0,0 -50,-30 -50,30 0,0 z',
          strokeColor: '#F00',
          strokeWeight: 1,
          fillColor: '#14143C',
          fillOpacity: 0.6,
          rotation: orientation
        },
        offset: '0%'
      }]
    });