I have a geometry in Houdini where some vertices have existing UVs, and some do not. I want to flatten the UVs of the whole object while keeping the vertices with existing UVs pinned.
The UVs are vertex attributes, those do not have UVs are 0,0,0 vectors.
This could be done in blender, but I want a procedural way to do it. And I can not realize it in Houdini.
Any suggestions or guidance on how to achieve this would be greatly appreciated.

You can try something like this.