Hiya. I've been looking into ways of adding additional data into spine sprites, specifically things like additional masks for stuff like UV-based water ripples.

I'm finding it a bit hard to modify the material in UE effectively because I can't access individual mesh elements, so if there's more than one atlas I can't supply a mask manually to the material.

So I tried seeing what the vertex colour data contains and the answer is... nothing. I think maybe it can provide a tint, but it's not per-vertex. I tried defining a mask using the weights of two idle bones and that didn't do anything either. That's a huge waste of the vertex map.

Please add either per-vertex colour painting or push the bone weights into the vertex map. Alternately allow custom masks to be added to a secondary atlas for each mesh, perhaps one per channel, allowing for four masks. And while we're at it, add a pixel normal atlas as well.

Cheers!