);

  fetch('./data/china.geojson').then(res => res.json()).then(clip => {
    layer.setClipMask({
      data: clip,
      // type: mtkWind.MaskType.outside,
      type: mtkWind.MaskType.inside, // 默认是 inside，即只显示范围内的
    })
  });

  const sceneConfig = {
    postProcess: {
      enable: true,
      antialias: { enable: true },
    },
  };

  const groupLayer = new maptalksgl.GroupGLLayer('group', [layer, arrow], { sceneConfig });
  groupLayer.addTo(map);
</script>
</body>
</html>
