Facet Surface

Hi there,

Apologies as I’m sure I’ve missed this in previous conversations - but i was wondering the most efficient way to create simple geometric forms - its important and all surface remain planar and maybe a way of controlling the amount of surfaces. I’d prefer to keep this out of Grasshopper if possible,
I could trim rotated planar surfaces but I’m sure I’m missing something a lot more intuitive? Keen to hear your thoughts, 0ae185215754a11640e2a91114f92420 3bda2be2b188e26a554f2ecc2f7d8296 db3b36738ce4bb6484483e7f524e4fc2 df24303d1b5e8b004ed555c7a5fc244d f9caf775389f848fd787f458b59fdf59

Hello - in plain Rhino I would make some planes, run Intersect with with history recording on, among all the planes and then Gumball them to adjust - the intersection curves will fall on edges of the form - when it looks about right, select all the planes and CreateSolid - then refine from there. Seems like Grasshopper could do something here too.
BoxyThing.3dm (367.9 KB)

Hi Pascal,
Thanks so much for your prompt response, once a solid is created, is there a way to move a face with the gumball that maintains all other surfaces planar?
The screen-grab was created by exploding the model for communication purpose only - thus, my question is can i achieve this surface move without exploding?
Also is there a simple way to confirm a surface is planar?

I misread your OP, but I created a grasshopper file. So I just post it here anyway: facets.gh (11.9 KB)

Hi -
In addition to what was said…

You don’t need to explode a polysurface to move a surface. You can sub-object select a surface with Ctrl + Shift + LMB and can then move that surface.
Only in specific cases will the neighboring surfaces still be planar surface. For the objects that you are working with, they won’t.

You can use the SelPlanarSrf command but will need to explode a polysurface first.


The reading of Pascal’s suggestion makes me think of two possible approaches for the intended purposes:

  • Instinctive modeling
  • Unconstrained decision making
  • Direct modelling approach with a focus on the look & feel

1 - A first approach would consist of using a custom display mode which would allow to better see&analyse of the underlying implicit solid object.

What I see here is that if it would possible to develop sort of " Predictive Option " for the PlanaSrf command, we could then ask Rhino to fill all possible inner areas base on a set of Planar Crossing Lines

  • History Relationship maintained.
  • Back Face custom display setting to highlight the underlying connect faces.

EdgeSrf does that but with a maximum of 4 inputs.

2 - A second approach would consist of using clipping planes to make the form finding process more instinctive and the usage more intuitive.
In this case there are probably some nice directions to explore in order to find ways to convert the resulting “visually shaped form” into a valid Solid Object.
Such use of clipping planes implies limitations regarding the intended purpose.

But this is probably a good way for artists to stay concentrated on the core objective, Form Finding.

Rodolfo Santos


Regarding the question the flatness of surfaces.

To avoid exploding any object, one possible approach is to use the Gumball to analyse the surfaces and fix any unwanted deviation ont the fly.

Hope this helps.
Rodolfo Santos

“Facet Surface” =
Alberto Giacometti (1901, Suisse - 1966, Suisse)
Le Cube[1933 - 1934]

Here is a python script that will check a surface’s or a polysurface face’s planarity (no need to explode) and report on the command line.

CheckFacePlanarity.py (979 Bytes)

Thankyou all - your time and expertise, it is greatly appreciated!