webgl加载3DTiles缓存

3DTiles文件格式

    var obj = [6378137.0, 6378137.0, 6356752.3142451793];
    Cesium.Ellipsoid.WGS84 = Object.freeze (new Cesium.Ellipsoid (obj[0], obj[1], obj[2]));
    var viewer = new Cesium.Viewer('cesiumContainer');
    var tileset = new Cesium.Cesium3DTileset({
        url: 'http://localhost:8080/3dtiles_zone1_gjxj/Scene/s3c_zone_gjxj.json',
        maximumScreenSpaceError : 1
    });
    var promise = viewer.scene.primitives.add(tileset);
    Cesium.when(promise,function(){
        viewer.zoomTo(tileset);
    })