Hi, I'm trying to understand how I can get 3- or 4-channel per-vertex data into the Graph Editor. From my tests, it seems that: the "Geometric Property" node does not give access to 4-channel data, "Geometric Property (vector3)" does not give me access to custom properties besides the ones defined in MaterialX core the "Texture Coordinates" node has a vector4f mode (yay!), but according to MaterialX spec, texcoords must have 2 or 3 channels, and I can't get 4-channel data to show up there either. My assumption so far is that I must be missing some "magic" – for example, do the primvars in a file have to be in a specific order, independent of their names? Or do their names matter? (E.g. convention would be primars:st and primvars:st1 and so on) Unfortunately the forum doesn't allow me to attach any USDZ or ZIP files or GDrive links; if there's a way to share a test file I'm happy to do so!

It seems that on iOS 13 & 14 environment probes are notably too dark, and never reach an acceptable brightness that matches the surrounding environment. Is there any way to get "reasonable" IBL lighting in QuickLook that is not like 50% gray all the time, without resorting to hacks such as using emissive colors/textures? Clearly there must be something wrong with the IBL estimation, as the same scene in Google SceneViewer is very bright and nice under the same circumstances. The issue reproduces for example with the QuickLook gallery; the ceramics piece there is nearly 100% white as per the USD file but renders dull and gray next to a physical ceramics piece. Video of the issue: drive.google.com/file/d/14mVQFTNe6pO_4tYNIvpZa9eAS2YzoVPO/view?usp=sharing More pictures: drive.google.com/drive/folders/1ej6g-gpBAu53z2Zn08eQFNZAkTmDA_XJ?usp=sharing Note that in those pictures, all spheres in that grid are purely white, with varying degrees of metallic and roughness being the only difference. My expectation would be that the diffuse ones would appear "white" and not dark grey; seems impossible to get a "realistic" picture. Happens here as well: https://developer.apple.com/augmented-reality/quick-look/models/cupandsaucer/cup_saucer_set.usdz

USDZ files can have light source information. Is this supported in Quick Look? (e.g. point/spot/directional)

Is there documentation about animation support in USDZ? Basic animation support is there, but a lot of details are not documented, e.g. only integer time codes are not supported (FB7612617), there's really low memory constraints around animation length and object count, only specific bone orientations are supported for skinned meshes (FB7701501) Instead of stabbing in the dark, it would be great to have proper docs for this, especially around the memory constraints. I think all of the above are bugs (didn't get any reaction so far) but still I think documentation for the status quo is required... Does anyone have more insights into this?