【SDK】【Cesium】【图层导入时，先清除所有图元】

Author: killer1992

src/service/3DPlot/PlotLayer3D.js

@@ -236,6 +236,7 @@ class PlotLayer3D extends Observable {
      */
     fromJSON(geoJson) {
         if (geoJson.type === "FeatureCollection") {
+            this.removeAll();
             const {features} = geoJson;
             features.forEach((s) => {
                 this._addGeoJSONObject(s);