如何使用OpenLayers 3在多边形中绘制后获取多边形点？

<script src="https://cdn.jsdelivr.net/npm/ol@3.20.1/dist/ol.js"></script>

<div id="map" style="width: 100%; height: 400px;"></div>

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
  })
});

var source = new ol.source.Vector();
var draw = new ol.interaction.Draw({
  source: source,
  type: 'Polygon'
});
map.addInteraction(draw);

draw.on('drawend', function(event) {
  var feature = event.feature;
  var geometry = feature.getGeometry();
  var coordinates = geometry.getCoordinates()[0]; // 获取多边形的第一个环的坐标数组
  console.log(coordinates);
});