cesiumgist

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

var ellipsoid = viewer.scene.globe.ellipsoid;
//var pos = Cesium.Cartesian3.fromDegrees(-111.0, 40.0, 150000.0);
var lat = 39.2904;
var lng = -76.6;

function loc2wgs() {
    return Cesium.Cartesian3.fromDegrees(lng, lat, 150000.0)
}

var entity = viewer.entities.add({
    position: new Cesium.CallbackProperty(function(time, result){
        return loc2wgs();
    },
    false
  ),
    ellipse : {
        semiMinorAxis : 800000.0,
        semiMajorAxis : 800000.0,
        height: 0,
        material : new Cesium.Color(228, 240, 245, .1),
        outline : true,
        outlineColor : new Cesium.Color(228, 240, 245, .5),
        outlineWidth: 5
    }
});

var handler = new Cesium.ScreenSpaceEventHandler(viewer.canvas);
var dragging = false;
handler.setInputAction(
    function(click) {
        var pickedObject = viewer.scene.pick(click.position);
        if (Cesium.defined(pickedObject) && (pickedObject.id === entity)) {
            entity.ellipse.scale = 1.2;
            dragging = true;
            viewer.scene.screenSpaceCameraController.enableRotate = false;
        }
    },
    Cesium.ScreenSpaceEventType.LEFT_DOWN
);

handler.setInputAction(
    function(movement) {
        if (dragging) {
            var cartesian = viewer.camera.pickEllipsoid(movement.endPosition);
            var cartographic = ellipsoid.cartesianToCartographic(cartesian);
            lng = Cesium.Math.toDegrees(cartographic.longitude).toFixed(2);
            lat = Cesium.Math.toDegrees(cartographic.latitude).toFixed(2);
            //loc2wgs(lat, lng);
            entity.position.setCallback(loc2wgs, false)
            //pos = Cesium.Cartesian3.fromDegrees(lng, lat, 150000.0);
            
        
        }
    },
    Cesium.ScreenSpaceEventType.MOUSE_MOVE
);

handler.setInputAction(
    function() {
        entity.ellipse.scale = 1;
        dragging = false;
        viewer.scene.screenSpaceCameraController.enableRotate = true;
    },
    Cesium.ScreenSpaceEventType.LEFT_UP
);