Plotting great circle lines in Cesium (just getting started)?

Question

How does one plot Great circle lines in Cesium (3D, not 2D) using the WGS84 ellipsoid? I found something like this in another thread but I'm having trouble applying it to my application (simply plotting great circle PolyLines of a given width and colour.

Also, I noticed that Google Maps have a light blue line within a dark blue line. Is it possible to draw this on Cesium in one go, or should I use two separate lines? And how would I place markers at the beginning and end?

As you can see, I'm just getting started with Cesium, but I would like some insight.

I am trying to plot great circle lines between airports. The data for each airport is in a JSON object, and the sub-objects look like this:

var airportData = {
    ...
    "EDDM": {
        "icao": "EDDM",
        "iata": "MUC",
        "name": "Munich International Airport",
        "city": "Munich",
        "state": "Bavaria",
        "country": "DE",
        "elevation": 1487,
        "lat": 48.3538017273,
        "lon": 11.7861003876,
        "tz": "Europe\/Berlin"
    },
    ...
    "KSFO": {
        "icao": "KSFO",
        "iata": "SFO",
        "name": "San Francisco International Airport",
        "city": "San Francisco",
        "state": "California",
        "country": "US",
        "elevation": 13,
        "lat": 37.6189994812,
        "lon": -122.375,
        "tz": "America\/Los_Angeles"
    }
    ...
}

And the function to actually plot the lines:

function plotLine(start, end)
{
    var viewer = new Cesium.Viewer("map");

    var origin_lat = start.lat;
    var origin_lon = start.lon;
    var dest_lat = end.lat;
    var dest_lon = end.lon;

    // What goes here?
}

And if someone could put an example that works in the Cesium Sandcastle that would be great.

Answer 1

Use a Polyline for something like this. Here's a live demo.

var viewer = new Cesium.Viewer('cesiumContainer');

var airportData = {
    "EDDM": {
        "icao": "EDDM",
        "iata": "MUC",
        "name": "Munich International Airport",
        "city": "Munich",
        "state": "Bavaria",
        "country": "DE",
        "elevation": 1487,
        "lat": 48.3538017273,
        "lon": 11.7861003876,
        "tz": "Europe\/Berlin"
    },
    "KSFO": {
        "icao": "KSFO",
        "iata": "SFO",
        "name": "San Francisco International Airport",
        "city": "San Francisco",
        "state": "California",
        "country": "US",
        "elevation": 13,
        "lat": 37.6189994812,
        "lon": -122.375,
        "tz": "America\/Los_Angeles"
    }
};

function plotLine(start, end, name)
{
    var origin_lat = start.lat;
    var origin_lon = start.lon;
    var dest_lat = end.lat;
    var dest_lon = end.lon;

    var line = viewer.entities.add({
        name : name,
        polyline : {
            positions : Cesium.Cartesian3.fromDegreesArray([origin_lon, origin_lat,
                                                            dest_lon, dest_lat]),
            width : 7,
            material : new Cesium.PolylineOutlineMaterialProperty({
                color : Cesium.Color.DEEPSKYBLUE,
                outlineWidth : 4,
                outlineColor : Cesium.Color.DARKBLUE
            })
        }
    });

    return line;
}

plotLine(airportData.EDDM, airportData.KSFO, 'Path from EDDM to KSFO');

viewer.zoomTo(viewer.entities);