Our glTF viewer doesn't work entirely just yet. Here's what I found so far:

• Tangents/bitangents are not computed correctly if not present in the model
• We always use the default sampler instead of using the sampler described in the glTF file
• Vertex colors are ignored
• Transforms (rotation in particular) are not always handled properly

I found these issues while trying to load various Sketchfab assets.