铯：根据缩放级别显示/隐藏标签

Question

当缩放比例增加到一定程度以上时，我想隐藏地图的标签。

对于此示例，我要在缩放级别5之后隐藏与collection1相关的所有标签： 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相机并没有意识到“缩放级别”，但是您可以使用translucencyByDistance在一定距离后关闭标签。

例如，以下是您的演示，其中已将translucencyByDistance添加到每个标签：

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);

Answer 2

有人知道是否有解决此问题的解决方案时考虑了屏幕尺寸吗？ 摄像头距离与标签大小的变化可能会发生根本性的变化，例如从iPhone上的标签混乱和重叠，到大屏幕的显示器（有足够的空间来显示所有标签）。