Declan Flynn (jdeclanflynn)

2 replies · posted

Locating the dreaded N-Gon

So, I've learned that n-gons are bad and that quads are good (agree or disagree?).  I've also heard that triangles, albeit not as bad as the dreaded n-gon, are not preferred either.

My current side project features a low-poly van as the centerpiece, and it's looking pretty good. However, I'm finding n-gons peppered throughout the mesh.  What can I say? It happens.

I've heard that a sure fire method of finding n-gons is to insert an edge loop. If the mesh won't accept an edge loop, then you have a poly with more than 4 vertices. So, I've been doing that regularly, but I find that it works sort of one face at a time, if that makes sense. It doesn't find all the n-gons.

So, I discovered a new method that I thought I'd share that seems to work pretty darn well. Now, you experts out there may scoff at this method, or share a faster way using one of those fancy five fingered hotkey combos. Others, however, may find this process very useful.

  1. Select your Object and tab into Edit mode. 
  2. Go into Face mode vs. Edge or Vertex mode, or press 3.
  3.  Click the Select tab.
  4. Scroll down to Select by Trait and click Faces by Sides. 
  5. If you don't see the elusive little tool properties menu that likes to appear and disappear like a Ninja, press T to toggle the tool properties menu 
  6. Set the value for Number of Vertices to 4 
  7. For Type, changed it to Greater Than. 

The result was an instant selection, highlighting all the n-gons in my mesh (see image below).

For me personally, I think this is a very useful tip, and I hope you will find it useful too!

Thanks in advance for your comments and suggestions.

  • jdeclanflynn that is a great way of finding N-gons! 

    I use it often, but leave the setting at the default (make sure to de-select everything (ALT+A) before doing this to get all non-quads:

    (And I have View > Adjust Last Operation un-checked, because it annoys me more than  it is helpful, so I press F9 to bring that up, when I need to make adjustments...)

    Now all quads are selected, so you can press CTRL+I to invert the selection and get all triangles and N-gons.

    There are however many situations, where N-gons and triangles are not bad; here is a great explanation by Gleb Alexandrov:

    https://www.youtube.com/watch?v=BjnCV2PIkKA

  • crew

    Great tips! 

    So, I've learned that n-gons are bad and that quads are good (agree or disagree?).  I've also heard that triangles, albeit not as bad as the dreaded n-gon, are not preferred either.

    Definitely a tricky subject - I'll say that none are bad or good, but it's true that n-gons and triangles are frequently less desirable in many common situations. Hopefully I can do a more in-depth video soon, but that video by Gleb that spikey linked to above is a good one. If you're still getting started with modeling though, I wouldn't worry about it too much - focusing on creating meshes with only quads is a great rule of thumb that I'd still recommend sticking to until you  have an excellent reason for breaking it.