Bug: FBX import does not respect Ngons, it converts to triangles

hi McNeel team,

We were having trouble with some imported lowpoly models when turned to SubDs. We know the form was looking good in Blender, but not in Rhino.

In this case, we were importing as FBX. And we noticed that at import Rhino is adding triangles.

I think we had this issue before, several times, but not sure if it was in FBX, or OBJ, but it’s been reported. Why is this still happening? I do not see any import options to prevent this from happening.



Do you have a simple FBX file you can share? One that imports great in Blender, but not so in Rhino?

hi Nathan, @juan_b can send it to you privately (message). The file was generated in Blender. And when we test re-import to Blender we do not see the added triangles.

Also it would be great to have a nicer live-link between Rhino-Blender so we don’t have to deal with any of this. Just sayin’ :wink:


Cool, I’d like the .blend file as well then, please. I have my 2.91.2 fired up already (:

I hear you. It’s just that I need to stop writing bugs that cause crashes - trying really hard! But Rhino-Blender interop is high on my personal list.

that’s great to know. Rhino-Blender interop would be a huge asset for our work and quality of life.

Since we are talking dream workflow here… could you even port the opennurbs kernel to a Blender plugin so the Nurbs Rhino objects show as Nurbs in Blender?


There was a Google Summer of Code project in Blender years ago where a student worked on loading brep objects using OpenNURBS, and write tessellation code for faces and their trims. It worked to some level, but unfortunately the student never finalized the work.

But with Rhino Inside we have the possibility to get the kernel really close to Blender. This is the type of interop that I’m working on (on and off between the current work).

I’m probably biased here, but I think if McNeel gave you more support to prioritize this work, the benefits would be a lot greater, easier, faster, cheaper, and with much more impact than any improvements your team can do in materials + shaders + render + UVunwrap + animation + sketch markup +… you get the point.

A biased user? Never heard of that! :wink:

Anyway - I put certain code in Rhino, I need to ensure it doesn’t make users cost too much time and money. There’s some big gains to be had, the tasks are unfortunately less easy than back when I did the very first proof of concept (: I need to own it up, so to speak.

It is not so much about prioritization of cool new other stuff, rather just I need to clear out my list before getting on.