Load GLB file with Properties / Inspector about xeokit-sdk

[AlexanderMelde]

Thank you, this helps us a lot!

[xeolabs]

Hi Alexander,

Note that glTF/GLB does not contain IFC semantic data (metadata), it only contains model geometry and materials.

To load IFC semantic data, you need to also load a JSON file alongside the glTF/glb that supplies the element hierarchy and property sets to xeokit, eg:

    const sceneModel = gltfLoader.load({
        id: "myModel",
        src: "../../assets/models/gltf/Schependomlaan/glTF-Embedded/Schependomlaan.gltf",
        metaModelSrc: "../../assets/models/gltf/Schependomlaan/Schependomlaan.json",
        edges: true
    });

• Run this example

Note also that we usually convert the glTF/glb to XKT for best results. Loading glTF/glb is possible, but XKT does some pre-conditioning to the data that makes it load a lot faster for large models.

We offer a couple of flavors of IFC->glTF/XKT conversion, but only one of them supports property sets at this time.

More information on IFC conversion here: https://xeokit.github.io/xeokit-model-conversion-tests/ifc-tests.html

If your enterprise needs prioritised support while evaluating xeokit, we'd be happy to help - if so, please get in touch here: https://creoox.com/en/contact/

thanks
Lindsay

[AlexanderMelde]

Hello Lindsay,

thank you for these explanations!
The links provided are useful as well for understanding the different file types.

I now have two follow-up questions:

1. Does the GLTFLoaderPlugin use convert2xkt.js internally?
2. Does the metamodel JSON file follow a certain standard, or is this a xeokit-specific format? I found a repo called xeokit-metadata, does this schema contain the structure for these JSON files? And I assume it is not ifcJSON?

Thank you for your help!

[xeolabs]

Hi no problem -

1. Does the GLTFLoaderPlugin use convert2xkt.js internally?

No, that just loads the glTF/glb directly into the xeokit Viewer. Note that as it does this, it will do a couple of things to the geometry on-the-fly ( 1. convert vertex coordinates to tiled coordinate system for precise double-precision rendering, and 2. quantize the vertex positions to integers for lower memory usage), that convert2xkt does offline when creating XKT. This is one reason we often pre-convert to XKT first, so those two things don't have to happen at loading time.

FYI we use the loaders.gl library internally within that plugin, to parse the glTF/glb.

Also FYI: although XKT is what we recommend for IFC models, that plugin is actually the best option for loading triangulated LiDAR comprised of textured triangle meshes. It handles the big textures more smoothly than XKT does.

2. Does the metamodel JSON file follow a certain standard, or is this a xeokit-specific format? I found a repo called xeokit-metadata, does this schema contain the structure for these JSON files? And I assume it is not ifcJSON?

Yes, xeokit metamodel JSON conforms to the schema described here: https://github.com/xeokit/xeokit-convert/blob/main/specs/index.md

Currently we're at v10. It's not ifcJSON - it's more optimized for loading into xeokit.

The BIMSpot tool is not something we're collaborators on, so I'm not sure what the conformance of that is with our latest spec.