javascript - 铯 : display/hide Labels depending on the Zoom level

Question

当缩放比例增加到一定级别以上时，我想隐藏 map 的标签。

对于这个例子，我想在缩放级别 5 之后隐藏所有与 collection1 相关的标签: https://codepen.io/ollazarev/pen/XBWEEq

let viewer = new Cesium.Viewer('cesiumContainer', {
  animation: false,
  baseLayerPicker: false,
  fullscreenButton: false,
  geocoder: false,
  homeButton: false,
  infoBox: false,
  sceneModePicker: false,
  timeline: false,
  navigationHelpButton: false,
  navigationInstructionsInitiallyVisible: false,
});

let collection1 = new Cesium.LabelCollection();
collection1.add({
  position: Cesium.Cartesian3.fromDegrees(-101.678, 57.7833),
  text: 'Canada',
});
collection1.add({
  position : Cesium.Cartesian3.fromDegrees(-75.1641667, 39.9522222),
  text: 'Philadelphia',
});
viewer.scene.primitives.add(collection1);

let collection2 = new Cesium.LabelCollection();
collection2.add({
  position: Cesium.Cartesian3.fromDegrees(-74.0059728, 40.7127753),
  text: 'New York',
});
collection2.add({
  position : Cesium.Cartesian3.fromDegrees(-79.38318429999998, 43.653226),
  text: 'Toronto',
});
viewer.scene.primitives.add(collection2);

Answer 1

Cesium 的 3D 相机本身并不知道“缩放级别”，但您可以使用 translucencyByDistance 在距离一定距离后关闭标签。

例如，这又是您的演示，其中每个标签都添加了 translucencyByDistance:

let viewer = new Cesium.Viewer('cesiumContainer', {
  animation: false,
  baseLayerPicker: false,
  fullscreenButton: false,
  geocoder: false,
  homeButton: false,
  infoBox: false,
  sceneModePicker: false,
  timeline: false,
  navigationHelpButton: false,
  navigationInstructionsInitiallyVisible: false,
});

let collection1 = new Cesium.LabelCollection();
collection1.add({
  position: Cesium.Cartesian3.fromDegrees(-101.678, 57.7833),
  text: 'Canada',
  translucencyByDistance : new Cesium.NearFarScalar(6.0e7, 1.0, 7.0e7, 0.0)
});
collection1.add({
  position : Cesium.Cartesian3.fromDegrees(-75.1641667, 39.9522222),
  text: 'Philadelphia',
  translucencyByDistance : new Cesium.NearFarScalar(4.0e7, 1.0, 7.0e7, 0.0)
});
viewer.scene.primitives.add(collection1);

let collection2 = new Cesium.LabelCollection();
collection2.add({
  position: Cesium.Cartesian3.fromDegrees(-74.0059728, 40.7127753),
  text: 'New York',
  translucencyByDistance : new Cesium.NearFarScalar(1.0e7, 1.0, 3.0e7, 0.0)
});
collection2.add({
  position : Cesium.Cartesian3.fromDegrees(-79.38318429999998, 43.653226),
  text: 'Toronto',
  translucencyByDistance : new Cesium.NearFarScalar(3.0e7, 1.0, 5.0e7, 0.0)
});
viewer.scene.primitives.add(collection2);