The Entity API doesn’t currently have a way to get the underlying active animations (or control animations at all), however you can use the below function to get them from the underlying Model primitive. Here’s a function that does that (or returns undefined if the entity doesn’t have a current model loaded). We definitely plan on adding animation support to the entity level in the future.
function getActiveAnimations(viewer, entity){
var primitives = viewer.scene.primitives;
var length = primitives.length;
for(var i = 0; i < length; i++){
var primitive = primitives.get(i);
if(primitive.id === entity && primitive instanceof Cesium.Model){
return primitive.activeAnimations;
}
}
return undefined;
}