Displaying a tile when disconnected

CesiumJS
1

Is it possible to determine whether or not Cesium has an internet connection and based on that use a SingleTileImageProvider to display one or more tiles when disconnected? I’ve been playing with this but haven’t gotten it to work. I’ve tried a few cuts at this but none seem to work even approximately. e.g.:

var viewer = new Cesium.Viewer(‘cesiumContainer’);
var layers = viewer.scene.imageryLayers;
layers.addImageryProvider(new Cesium.SingleTileImageryProvider({
url : tileUrl,
rectangle : tileArea
}));

``

This displays both the default globe and the single tile when connected, but if disconnected it displays neither, just the globe outline. On the other hand:

var viewer = new Cesium.Viewer(‘cesiumContainer’, {
imageryProvider: new Cesium.SingleTileImageryProvider({
url : tileUrl,
rectangle : tileArea
})
});

``

flat out doesn’t work, neither displaying the tile when connected nor displaying even the globe outline when disconnected.

Thank you.

–Dale

2

The second one is going to outright fail because you’re overriding the default imagery providers, which fails a bit more gracefully when there is no internet connection.

This stack overflow article http://stackoverflow.com/questions/2384167/check-if-internet-connection-exists-with-javascript may help you.

You can delay the Cesium Initialization until after you’ve determined the state of your internet connection.

3

Mike,

Makes sense. I figured this largely was about me not knowing what I was doing. :wink: The question would be, though, even if I performed some kind of connection testing, how would I initialize Cesium to use a small set of tiles at that point? Or is it simply not possible?

–Dale