Check if Model has any default hidden elements in Forge's 3D Viewer

Some background:

I'm using Forge to visualize IFC models. Some of my uploaded models have IfcOpeningElements which seems to be hidden in Forge by default, at least when setting ghosting to false via viewer.setGhosting(false). I'm also having functionality to hide normal elements in the viewer (viewer.hide(dbIds, model)), and to show/hide all elements (model.setAllVisibility(show)).

The problem I'm having is that I want to be able to show/hide the IfcOpeningElements regardless of showing and hiding "normal" elements.

The approach I tried, which is not working very well is to call model.visibilityManager.getHiddenNodes(). The problem with this approach is that, even for models with IfcOpeningElements, getHiddenNodes only returns a non-empty array after ~15 seconds (probably varies with the size of the model). In the meantime, if the user does anything that makes the app call model.setAllVisibility(true), I'm no longer able to detect the original hidden IfcOpeningElements. Furthermore, when calling getHiddenNodes after an arbitrary waiting period after the model has loaded, I'm not sure if it returns an empty array because the model is not "ready" to detect hidden elements from IfcOpeningElements or if the model simply does not have any IfcOpeningElements.

So, Is there any good way to detect if a model has any "default" hidden elements without having to wait long after the model is loaded? Or perhaps there is a way to call change the visibility of the entire model without changing the visibility of the IfcOpeningElements?

I'm aware of the possibility to listen to the HIDE_EVENT event, but since I'm not sure if it will fire at all (since I'm not sure if the model has any IfcOpeningElements), I cannot block the application from calling model.setAllVisibility(true) which in turn would make getHiddenNodes() return an empty array even if there was hidden elements to begin with.

Solution

How about just skipping loading IfcOpeningElements' geometries? To do so, pass skipHiddenFragments: true to the 3rd argument of Viewer3D#loadDocumentNode

viewer.loadDocumentNode(
    doc,
    viewable,
    {
        skipHiddenFragments: true
    }
);

This approach will skip loading the IfcOpeningElements' meshes, but you can still see their properties while selecting IfcOpeningElements on the model structure panel. On the other hand, you cannot access their bounding boxes and geometries with this approach.

Regarding how to check default hidden elements, try to call this code after all geometries are loaded. The hiddenDbIds are elements hidden by default.

let model = viewer.getAllModels()[0]; //!<< Check the first model just for demo
let fragList = model.getFragmentList();
let hiddenDbIds = Object.keys( fragList.vizflags ).filter(fragId => !fragList.isFragVisible( fragId )).map(fragId => fragList.getDbIds( fragId ) );

// hiddenDbIds.forEach(dbId => viewer.getProperties(dbId, console.log))

Note. The visible flag will also be changed after changing the objects' visibility. So, ensure that run the above before changing the visibilities.