Openlayer3 -避免多段线在动画过程中消失

// 创建地图容器
var map = new ol.Map({
  target: 'map',
  layers: [
    new ol.layer.Tile({
      source: new ol.source.OSM()
    })
  ],
  view: new ol.View({
    center: ol.proj.fromLonLat([0, 0]),
    zoom: 2
  })
});

// 创建多段线要素
var lineFeature = new ol.Feature({
  geometry: new ol.geom.LineString([
    [0, 0],
    [10, 10],
    [20, 0],
    [30, 10],
    [40, 0]
  ])
});

// 创建矢量图层
var vectorLayer = new ol.layer.Vector({
  source: new ol.source.Vector({
    features: [lineFeature]
  })
});
map.addLayer(vectorLayer);

// 动画绘制多段线
var lineCoords = lineFeature.getGeometry().getCoordinates();
var lineLength = lineCoords.length;
var currentCoordIndex = 1;

function animateLine() {
  if (currentCoordIndex < lineLength) {
    var animatedLine = new ol.Feature({
      geometry: new ol.geom.LineString(lineCoords.slice(0, currentCoordIndex))
    });
    vectorLayer.getSource().clear();
    vectorLayer.getSource().addFeature(animatedLine);
    currentCoordIndex++;
    setTimeout(animateLine, 100);
  }
}

animateLine();