You can read the vertex information in Blender, it’s pretty flexible.
I even made a small blender video.
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Vertex painting is a good fit for sculpting softwares since you don’t have to care about UVs.
But otherwise proper texturing with UVs is the way to go (substance painter, etc).
Since Nomad is mostly a sculpting app and I knew I was not going to support UV (at least for a while), I wanted a robust layer+painting system.
I wouldn’t say this was the hardest thing to do.
The tricky thing was to make sure the layers could be kept even when changing the topology.
It’s something that I wanted to do as it allows more flexible workflow.
So typically when you trim, merge, split, extract, use dynamic topology or even when using the voxel remesher, you always keep the painting and all the layers.