[Low poly] Procedural mesh colors

Hello,

I have a procedural terrain generated in C++ in a game that use the low poly style.
I’m currently working on biomes implementation, and I have a little issue :

Each vertex of the terrain has a FColor depending on what biome it is located, but sometimes, the color of generated triangle is a gradient between different colors of his 3 vertices.
I’d like the color of the triangle to be uniform without gradients.

So, I have this :

And I want this (like the great Astroneer do) :

http://lesplayersdudimanche.com/wp-content/uploads/2019/02/cover-test-astroneer-les-players-du-dimanche.jpg

How can I do this without duplicate the vertices of each triangles ? Do I need to write a custom shader ? Or do some Blueprint manipulations on the terrain material ?

Thanks for the help :slight_smile:

I answer to myself : the only way is to duplicate vertices.