            fill: new ol.style.Fill({
              color: 'rgba(0, 255, 0, 0.2)'
            }),
            text: new ol.style.Text({
              font: 'bold 12px sans-serif',
              text: f.get('face').id.toString(),
              fill: new ol.style.Fill({color: 'green'}),
              stroke: new ol.style.Stroke({
                color: 'white',
                width: 2
              })
            })
          });
          return [style];
        }
      });

      var map = new ol.Map({
   