hi,
i want to store some extra information in a gltf file. I know that the GLTF format supports this. In Blender, there is a "Custom properties" option which I can add to a mesh (int, float, string etc.) and when exporting this to gltf, it shows um in the gltf file

"meshes":[
{
"extras":{
"somestring":"test123"
},
"name":"Suzanne",
"primitives":[
{
"attributes":{
"POSITION":0,
"NORMAL":1,
"TEXCOORD_0":2
},
"indices":3
}
]
}

In Houdini, there is the "Export Custom Attributes" in the ROP GLTF Output node. I tried to add attributes as details to the mesh, but they dont show up in the gltf. In the docs it says:

When turned on, all public attributes are exported. When turned off, only attributes defined in the glTF standard are exported.

Attributes are exported with their original types whenever possible. However, glTF allows a maximum of 32 bits for floats and integers. Integers are also required to be unsigned. Attempting to export a datatype larger than this will narrow the type and print a warning.

Exported custom attribute names are the original names plus an _ (underscore) prefix.

As glTF only supports point attributes, name collisions will be resolved using the normal attribute resolution order.

I'm not entirely sure if I understand this information correctly: Only point attributes can be exported and not attributes via mesh?

Bump. SideFX?

Afaik this is not possible, you can write custom buffers with attributes, but that only adds to the buffer/bufferviews. No way to add data like the extras field. I also entered a RFE for this.

Here's a partial solution I stumbled upon yesterday : https://github.com/ToniMacaroni/HoudiniGLTFExtended/blob/main/README.md [github.com]
If you're able to patch it for you current release you have a glTF exporter that adds extra data and path functionality.

johanboekhoven, thank you for sharing repo.

I've made a pull request that solves build errors for Houdini 20-21.0+, adds install/build instructions (how to add it to Houdini): https://github.com/ToniMacaroni/HoudiniGLTFExtended/pull/1 [github.com]

My updated repo fork: https://github.com/animgraphlabgames/HoudiniGLTFExtended/tree/houdini-21-support [github.com]


Everything seems to be working based on what i've tested. Check pull request for more info.

@playfy [playfyhd.app] That's the right approach—using Blender's Custom Properties is one of the cleanest ways to store metadata, since they're exported into the glTF extras field and can be read later by applications that support it. Just keep the data organized and documented so it's easy to access and maintain as your project grows.

This isn't feasible, as far as I can tell. You can create custom buffers with characteristics, but it just increases the buffer/bufferviews. Like the extras field, there is no option to add data. For this, I also sent an RFE.