Painting a gradient on vertices

I’m trying to make a waterfall for my project . I watched a talk on how the waterfalls in rime were made
( GAT #65: Stylized VFX in RIME - YouTube ) and im trying to do something similar.

This method uses vertex colours to mask the water/foam. I’ve got it working for the most part but im having a problem were i have noticeable sharp changes were you can clearly see the change in vertex colour (pictures below).

The only solution i can think of is to have a smooth gradient painted on the vertices but i can’t figure out how to do this with my current setup. I use blender to model the meshes but it doesn’t have a gradient for vertex paint and i cant find one in unreal either (though i did try to manual paint one, it still has noticeable lines). I know some other modeling software has this function, but they are way out of my price range.

Does anyone know of a way I can do this within unreal? I was thinking there might be a solution to this using the material nodes but im not sure.

If anyone knows of any free or cheep software for vertex painting that has a gradient tool i would also appreciate that.

2019 04 10 15 24 12 - YouTube The screenshot doesn’t really show the problem. You can see it better in this video.

Ok. I solved this myself. Easy solution TBH. Will post incase anyone else needs.

I just multiplied the vertex color output by a gradient texture and when I paint the vertices all a solid colour I get a gradient. When I size the gradient texture correctly I have no more lines.