What triggers .b3dm files to load? Or have they always done so?

Hi again,

Doing some performance cleanup, and noticed in the browser’s Network tab that rather large .b3dm files are loaded after the initial 3DTileset is rendered to the screen. So, (mainly) two questions;

  1. Have they always done that? I don’t remember them doing it, but I could be wrong as they load in the background

  2. Either they’ve always done that, or there’s something triggering them to load. What could that be? What are the rules around this? Am I poking something (property) that starts that process upon a get?

I was tinkering with some events that load and examine the batchTable of incoming tiles, and I could understand it from that perspective, but this happens no matter what, even in old versions of our software that does nothing in terms of grabbing the Tilesets through the API (or otherwise). I tried backporting to earlier Cesium versions, and tried it one by one back to 1.76; should I keep going?

Any hints would be awesome!