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

var scene = viewer.scene; 
var ellipsoid = scene.globe.ellipsoid; 
var handler; 

// variables that support distance line 
var distPosCarte = []; 
var distPosCarto = []; 
var surfaceDist = 0; 
var distLine = viewer.entities.add({ 
    id : 'distLine', 
    name : 'Distance Line', 
    polyline : { 
        width : 3, 
        positions : [], 
        material : new Cesium.PolylineOutlineMaterialProperty({ 
            color : Cesium.Color.ORANGE, 
            outlineWidth : 2, 
            outlineColor : Cesium.Color.BLACK 
        }) 
    } 
}); 

handler = new Cesium.ScreenSpaceEventHandler(scene.canvas); 


handler.setInputAction(function(movement) { 
    // clear distPos arrays on single click without SHIFT 
    distPosCarto.length = 0; 
    distPosCarte.length = 0; 
    surfaceDist = 0; 
}, Cesium.ScreenSpaceEventType.LEFT_CLICK); 

handler.setInputAction(function(movement) { 
    var cartesian = viewer.camera.pickEllipsoid(movement.position, ellipsoid); 
    if (cartesian) { 
        distPosCarte.push(cartesian); 
        var cartographic = ellipsoid.cartesianToCartographic(cartesian); 
        distPosCarto.push(cartographic); 
        if(distPosCarte.length >= 2) { 
            var posArray = []; 
            // Build array with all points 
            for (var i = 0; i < distPosCarte.length; i++){ 
                posArray.push(distPosCarte[i]); 
            } 
            // Calculate surface distance between each point 
            for (var j = 1; j < distPosCarto.length; j++){ 
                var geodesic = new Cesium.EllipsoidGeodesic(distPosCarto[j-1], distPosCarto[j]); 
                surfaceDist += geodesic.surfaceDistance; 
            } 

            distLine.polyline.positions = posArray; 
            distLine.description = ((surfaceDist)/1000).toFixed(2) + ' km'; 

            viewer.selectedEntity = distLine; 
        } 
    } 
}, Cesium.ScreenSpaceEventType.LEFT_CLICK, Cesium.KeyboardEventModifier.SHIFT);