在 Cesium 中捕获缩小事件

Question

我想在用户将地图大小缩小到必须更改地图图像层的程度时立即捕获缩小事件。

var viewer = new Cesium.Viewer("cesiumContainer");
var scene = viewer.scene;
var clock = viewer.clock;
var referenceFramePrimitive;
var camera = viewer.camera;
....
camera.changed.addEventListener(function()
   {
    var height = Cesium.Cartographic.fromCartesian(camera.position).height;
    if(height<4251907)
    {
      var layers = viewer.imageryLayers;
      var baseLayer = layers.get(0);
      layers.remove(baseLayer);
      layers.addImageryProvider(new Cesium.IonImageryProvider({ assetId: 3812,  maximumLevel : 5 }));
    }
  console.log(height);
}.bind(camera));

有什么办法可以实现吗

谢谢

Answer 1

这是非常简单的解决方案之一。

    const viewer = new Cesium.Viewer("cesiumContainer");

    const camera = viewer.camera;

    const scratchCartesian1 = new Cesium.Cartesian3();
    const scratchCartesian2 = new Cesium.Cartesian3();

    let startPos, endPos;

    camera.moveStart.addEventListener(function () {
        startPos = camera.positionWC.clone(scratchCartesian1);

    });

    camera.moveEnd.addEventListener(function () {
        endPos = camera.positionWC.clone(scratchCartesian2);

        const startHeight = Cesium.Cartographic.fromCartesian(startPos).height;
        const endHeight = Cesium.Cartographic.fromCartesian(endPos).height;

        if (startHeight > endHeight) {
            console.log("zoom in");
        } else {
            console.log("zoom out");
        }

    });

在 Cesium 中捕获缩小事件

Capture zoom out event in Cesium

javascript

cesium