Merging Coplanar Faces of a mesh gone after triangulation

Rhino Rhino for Windows
1

after doing the Merge All Coplanar Faces on a planar mesh, it works, but after that, if I apply triangulate mesh command, it came back the same.
any solution to this? since they are planar, there only should be 2 triangular polygons per face, if I use reduce mesh, it may break the shape, especially if it is not rectangular.
the main goal is to reduce polygon count.

2024-11-08_222247_02
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1 Like
2

Hello! Is it possible for you to post the model? We could take a closer look to see what might be happening.

1 Like
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sorry for the late reply… thanks for trying
01.3dm (144.4 KB)

4

Thank you for sharing! This appears to be the version that was the result of the triangulate mesh command, is that correct? If so, would you be able to share the file prior to running the triangulate mesh command?

5

The MergeFaces command does not actually merge faces. It just hides edges between them before any later actions. The same happens using RhinoCommon API Mesh.MergeAllCoplanarFaces() method.

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Thanks for looking into the file, well actually the file contains two examples, one before and one after meshing, the one on the right is the one in question

7

Exactly! are there any workaround for this? any command or a script maybe?
thanks for helping

8

Hi Moaz -

FWIW, there is only one mesh in the file that you posted.

Simply refrain from triangulating the mesh?

For which application?
-wim

9

Thanks for answering Wim, I’m doing that for optimization purposes, I’m exporting FBX to a Game Engine (Unreal Engine) and the program (or any 3D rendering software) will triangulate the mesh when they import it, so the triangle count will be different! well so different! like 12,000 vs 12,000,000 !!! and the file size too! 12mb vs 50mb ~ish, I had to redo all the files for that, and it’s so frustrating, so if there is a way to solve this issue at least for planar mesh without losing the shape that happens when you use reduce mesh command

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Hi Moaz -

I doubt that. When you merge the faces in Rhino, and then run PolygonCount, isn’t the reported triangle count the same as what it is in the receiving application?

That’s because, under the hood, all meshes consist of triangles. In Rhino, you can choose to hide them on planar areas (with MergeAllCoplanarFaces or AddNgonsToMesh), but they are still there.
-wim

11

als long as your meshes / input is not to complex:
_toNurbs (each mesh-Face will become a nurbs surface)
_mergeAllCoPlanarFaces (which works different on polysurfaces then meshes)
_mesh (with simple planes checked and maximum Distance edge to surface set to 0, there is some inaccuracy in the data )

Screenshot 2024-12-02 at 11.59.10
Screenshot 2024-12-02 at 11.59.101804×734 100 KB

kind regards -tom

12

Thanks for the reply Tom_P, Exactly what I was doing until I come to redo walls and complex installations, things just got out of hand quickly! especially with flipped faces! that’s what happens most of the time
I wish rhino has a way to deal with such thing, you know like getting from the shape on the far left to the shape on the far right with a simpler way, I wish reduce mesh command was a bit more smarter, but I also know that Rhino isn’t the perfect place for working with meshes.