In cesium, how do you dynamically update a label over time? - cesiumjs

Question

I have a label that associated with a billboard/marker in cesium that I want to 'update' over time. I tried using a setTimeout to increment a variable 'count' that I assign as the label to a marker... but it doesn't increment. Is there something special I need to be doing or am missing?

Answer 1

You should be able to update a label just by changing its text property.
entity.label.text = 'new text';
Here's a full example:
var viewer = new Cesium.Viewer('cesiumContainer');
var image = new Image();
var entity;
image.onload = function() {
entity = viewer.entities.add({
position : Cesium.Cartesian3.fromDegrees(-75.1641667, 39.9522222),
billboard : {
position : Cesium.Cartesian3.fromDegrees(-75.1641667, 39.9522222),
scaleByDistance : new Cesium.NearFarScalar(1.5e2, 5.0, 1.5e7, 0.5),
image : image
},
label : {
text : 'Label on top of scaling billboard',
font : '20px sans-serif',
showBackground : true,
horizontalOrigin : Cesium.HorizontalOrigin.CENTER,
pixelOffset : new Cesium.Cartesian2(0.0, -image.height),
pixelOffsetScaleByDistance : new Cesium.NearFarScalar(1.5e2, 3.0, 1.5e7, 0.5)
}
});
viewer.zoomTo(viewer.entities);
};
image.src = '../images/facility.gif';
var counter = 0;
viewer.scene.postUpdate.addEventListener(function(){
if(!Cesium.defined(entity)) {
return;
}
counter += 0.04;
if(Math.cos(counter) > 0){
entity.label.text = "On";
} else {
entity.label.text = "Off";
}
});
And a live version on Sandcastle.