Manipulate color of specific vertices with shader

Custom UV
I found a function that should unwrap the model based on the normal of each face. Unfortunately it didn’t work and leads to the same results as the image in my previous post (https://www.babylonjs-playground.com/#9MPPSY#16). How is it possible to create a new uv data set for the whole surface. I can imagine that it will get complicated with more complex objects than just a box.

Decals
Decals solve the problem with the faces and uv map but is it just possible to use textures instead of dynamic forms? https://www.babylonjs-playground.com/#9MPPSY#15. Is it possible the create a heatmap with decals?

The result should look similar to this: