Keep Polygons Planar in Vellum?

[Frd]

I have this even geometry and want to create a tool, which allows to interactively add variation while these conditions are met:

• the inner face stays as it is and
• the surrounding faces remain planar (stretching is allowed).

I found this interesting article about polygon planarization and thought I could try it with Vellum. My goal is to create something like this, just resulting in planar faces:

I added a facet node with unique point and planar option on to check the result. My goal would be, that the outer faces stay connected.

Is there a constraint in Vellum which keeps the faces planar?

VellumPlanar_Problem.hipnc

[Frd]

The limitations are quite strict, maybe Vellum doesn't make sense here. Thinking a bit more I found out that I just need to stay on the y-plane and slide 2 points at once along the adjacent edges to keep the faces planar.

With ramps I create a weight attribute relative to the x and z bounds (cyan). New vectors are calculated by comparing adjacent points, multiplied it with the attribute from the ramps and looped according to the point count. Left: loop with nodes, right: a for loop in vex. The node version seems to be more sensitive with extreme values (non-planar faces are red).

Thanks to Matt's cgwiki and some other posts here, this was an interesting lesson in vex!

VEXPlanarTool.hipnc