Set instanceTree to a custom node in Forge 3D viewer - autodesk-forge

Question

Lets say I'm working with a 3D file which is the combination of one Architectural model and one Structural model.
The instance tree or Model Browser looks like this
root/
Arch/
Level 01/
Level 02/
...
Str/
Level 01/
Level 02/
...
I want to display only the Level 01.
So I:
Followed the steps in the Viewer tutorial
Add an event listener to both Autodesk.Viewing.GEOMETRY_LOADED_EVENT & Autodesk.Viewing.OBJECT_TREE_CREATED_EVENT
When the 2 are fired, I use the code in this article to display only the Level 01 without ghosting.
I have 2 problem with this approach
I have to wait until the entire model is loaded before I can filter the level
After filtering the level, if I click on Model Browser, I can still see the entire model structure (but with everything as hidden except Level 01). How can I set the instance tree to only have what's below?
root/
Arch/
Level 01/
Str/
Level 01/
EDIT
At what point am I supposed to override the shouldInclude() function?
I've tried this and put a breakpoint but it seems it never gets called... I also tried to move it around but in vain.
const start = Date.now();
Autodesk.Viewing.UI.ModelStructurePanel.shouldInclude = (node) => {
Logger.log(node);
return true;
};
Autodesk.Viewing.Initializer(options, () => {
Logger.log(`Viewer initialized in ${Date.now() - start}ms`);
const config = {};
// prettier-ignore
Autodesk.Viewing.theExtensionManager.registerExtension('MyAwesomeExtension', MyAwesomeExtension);
viewerApp = new Autodesk.Viewing.ViewingApplication('MyViewerDiv');
viewerApp.registerViewer(viewerApp.k3D, Autodesk.Viewing.Private.GuiViewer3D, config);
loadDocumentStart = Date.now();
// prettier-ignore
viewerApp.loadDocument(documentId, onDocumentLoadSuccess, onDocumentLoadFailure);
});

Answer 1

Regarding #1: the object tree is stored in the file's internal database which - for performance reasons - is only loaded after the actual geometry.
Regarding #2: you can subclass the ModelStructurePanel class and add your own behavior, for example, by overriding the ModelStructurePanel#shouldInclude method.

Answer 2

Since I wasn't able to understand how to use ModelStructurePanel, I overrode Autodesk.Viewing.ViewingApplication.selectItem to only modify the options which are either passed to loadDocumentNode or startWithDocumentNode as below:
const options = {
ids: leafIDs.length > 0 ? leafIDs : null, // changed this line
acmSessionId: this.myDocument.acmSessionId,
loadOptions,
useConsolidation: this.options.useConsolidation,
consolidationMemoryLimit: this.options.consolidationMemoryLimit || 100 * 1024 * 1024, // 100 MB
};
With leafIDs being an array of objectIDs to display. I was able to build it by:
querying the ModelDerivativeAPI using GET :urn/metadata/:guid
going through the tree to find the ids which I am interested in.
There's probably a more elegant way to do this but that's the best I could do so far.