How to align Vertices (Make coplanar)

Hi i am new to the forum so the searches i did may have not been correctly phrased, but I found no answers or mention of this problem.

  1. If the vertices of a quad or N-Gon are not co-planar, is there some way to make them so, and even more, to dictate which three vertices determine that plane?

Snapping to the grid obviously is not an option for faces not perpendicular to an axial plane.

The workaround I am using is so embarassingly complicated that I hesitate to mention it, but I can select three vertices, duplicate them, make a face ( a sad one!) and scale it up until I can snap the noncoplanar vertices to it and then delete the ‘guide’ face.

  1. Is there a script or menu item to correct all N-Gons in a mesh to have coplanar vertices with the minimum displacement of geometry?

Surely these problems are very common?

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as i remember NGON are always co planar or it is not defined as NGON!

can you show pics of example for problems you have
and may be upload a sample file se we can look at it!

thanks

For faces that are aligned with global axes, you can just make your pivot as active element (alt+period) and scale to 0 along an axis.

If the faces are not aligned to global axes, you need to somehow get the orientation for scaling. Here’s one example on how to do that:



On the left I’ve selected a face that is aligned like I want the ngon to be aligned. View transform orientation is used to scale those vertices, and pivot point is set to active element, then Shift+numpad_7 to align to that face. On the right there is ngon vertices selected and active vertex selection outside the ngon is for the pivot (active element). S,Z,Z,0 to scale to 0 along view Z axis.

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JA12, when I use ALT period, nothing happens… can you clarify?

What i usually do is create a custom axis… select a face, then press ctrl alt space… then the same szz0 will work aswell but from any angle.

It changes the pivot point to “active element” mode. Pivot menu is highlighted in the screenshot (left arrow).

Thanks JA12 and DoubleBishop! You have understood my problem exactly.

For faces that are aligned with global axes, you can just make your pivot as active element (alt+period) and scale to 0 along an axis.

Yes this is not a problem with increment snapping although it could be easier…

you can just make your pivot as active element (alt+period) and scale to 0 along an axis

This uses the normal which is not always what I want… a face with the right normal is not always there in the same object!

select a face, then press ctrl alt space… then the same szz0 will work aswell but from any angle

DB, can you tell me what this shortcut is for? I think I am having the same problem with this method, viz. a face with the right orientation is just not present in the object I am editing.

I’m sorry if I used the term N-Gon incorrectly? What is the term for a polygon in which the vertices are not coplanar?

Ctrl+alt+space creates a custom transform orientation (and switches the orientation mode to that). With that you can select a object/vertex/edge/face and get their orientation saved. You can view/add/remove those on the properties panel (N).

That is useful for example if you create a handrail for stairs and want to move new elements or objects along that rail. You could select one of the faces or edges, create new custom orientation and then be able to constrain your transformations to that.
Transform widget always aligns to what is selected as orientation (alt+space) and with hotkeys you select that as a secondary axis constraint.

Here I’ve created a custom orientation from one of the handrail edges and moving another object along Edge Z (G,Z,Z)


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Hi Dru I’m you! I’m replying to my own thread for the benefit of anyone searching for a solution to the same problem – all the answers here are helpful but Bart Crouch’s Addon called looptools has a flatten tool in it that does exactly this add offers some alignment options to boot. Go Bart! Also some very ueful other tools in the package. I recommend activating it.

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Here’s a quick solution:

Section off a triangle which is pointed in the direction you want (j key while selecting two vertices to make a triangle within an existing mesh.

Now change the transform pivot point to “active” and the transform orientation to “normal” select the remaining Ngon (and any other faces/verts you want coplanar) and make sure to select your target triangle last so that it’s active. Press sz0 (scale, along normal, to zero) et voila! Nothing complicated necessary.

Having the gizmos visible during this process helps a lot.