Environment Modeling: Triangles and 4+ Sided Vertices Yay or Nay??

Amank679

Hi everyone,

I wanted to know if triangles and 4+ sided vertices are acceptable in modeling environment assets (props)?

I know 4+ sided verts are a nightmare in rigging characters but if I'm connecting another object to my main object (Cylinder for example) without pipeshoving, If while using the multicut tool I connect 5+ edges to one vert, is that acceptable?

Also Are triangles acceptable? I know game engines convert quads to tris anyway but clarification would be really helpful.

Thanks!

Mark Dygert

It all gets broken down into tris in the game engine, so it's really about your workflow. It's easier in most cases to work with quads in loops and rings which work best if they are mostly on a grid. But it is perfectly ok to use n-gons with more or less than 4 sides.

sprunghunt

Mark Dygert said:

It all gets broken down into tris in the game engine, so it's really about your workflow. It's easier in most cases to work with quads in loops and rings which work best if they are mostly on a grid. But it is perfectly ok to use n-gons with more or less than 4 sides.

There is not enough control over N-gons triangulation to ensure clean geometry and good looking models. Especially if you’re not used to modeling. 

Mark Dygert

Yeah sort of, but in 3dsmax you can control the direction of non-visible edges without having to muck up your topology or edge flow (Edit Poly > Edge Mode > Edit Triangulation). It's much better to do that than stick dogmatically to "100% all quads all the time" and make an inefficient mess with edges going all over trying to preserve quads. 
https://knowledge.autodesk.com/support/3ds-max/learn-explore/caas/CloudHelp/cloudhelp/2017/ENU/3DSMax/files/GUID-18FC1E1C-226F-426B-B550-6BAA07C3FFE3-htm.html


A well placed n-gon can act like a center hub in a train yard.


Maya has this also but it's mostly useless, because it will enforce tri-striping from lower left to upper right if you make any changes or move a vert around.
https://knowledge.autodesk.com/support/maya/learn-explore/caas/CloudHelp/cloudhelp/2016/ENU/Maya/files/GUID-97AC9716-FC94-4ABA-B64D-D660183C6AD4-htm.html

Amank679

Mark Dygert Thanks for the reply! I'm not sure what you mean by non-visible edges, is that similar to internal faces and edges?

Also, edge loops tend to add several extra quads so I always feel tempted to just to avoid edge loops and just making tries connecting to certain verts via the multicut tool. I'm not sure if employers would consider that as clean topology if I have triangles around to slip ngons. 

My other question is if I 4+ sided vertex, would that be considered clean topology?
For example, If I booleaned a cylinder through an already fairly complex object and connected several of the verts from the booleaned hole to say the top left and top right corner creating a vert that as 5-8 (Maybe more) edges coming out of it, is that acceptable? 

sprunghunt

Amank679 said:

Mark Dygert Thanks for the reply! I'm not sure what you mean by non-visible edges, is that similar to internal faces and edges?

Also, edge loops tend to add several extra quads so I always feel tempted to just to avoid edge loops and just making tries connecting to certain verts via the multicut tool. I'm not sure if employers would consider that as clean topology if I have triangles around to slip ngons. 

My other question is if I 4+ sided vertex, would that be considered clean topology?
For example, If I booleaned a cylinder through an already fairly complex object and connected several of the verts from the booleaned hole to say the top left and top right corner creating a vert that as 5-8 (Maybe more) edges coming out of it, is that acceptable? 

Clean topology has nothing to do with whether you mesh has tris or quads or n-gons. 
Clean topology to me means: 

• fairly even triangle spacing with no ultra long, thin, triangles or necessary small triangles
• no overlapping triangles that cause bad smoothing
• triangle fans are avoided and geometry is setup for optimal tri-stripping
• geometry is setup in a way that supports efficient UV mapping
• geometry is setup in a way that supports a good normal map bake. 

It's easier for a beginner to see mistakes in topology if you don't use n-gons. If you have the same amount of modeling experience as Mark Dygert then N-gons might be something that's ok to use. 

Amank679

@sprunghunt At my University Ngojs are a big no no. They say Quads and Tris are much more preferable.

I'm hearing a lot about "triangle stripping" but I've never heard it before. Could you please explain what this is?

EarthQuake

If you're not using n-gons while modeling you're making life much harder on yourself. There is absolutely no reason why you can't use n-gons while working. N-gons can be very helpful with sub-d modeling as well, despite some dogmatic claims that you should always use quads.

However, when prepping to export a final assets to game, it's common practice to convert n-gons to quads/tris, just to make sure the exporter (or importer) doesn't make a mess of it.

There is little logical reason to avoid triangles either. I mean, you shouldn't build your entire mesh out of triangles, but some surfaces are best suited to triangles and sticking to quads because of some dogma isn't helpful.

sprunghunt

Amank679 said:

@sprunghunt At my University Ngojs are a big no no. They say Quads and Tris are much more preferable.

I'm hearing a lot about "triangle stripping" but I've never heard it before. Could you please explain what this is?

Triangle stripping is an optimization for the way models are drawn in a game engine. Triangles are stored as strips where vertexes are shared. This means that fans where more than four edges meet at a vertex will cause more strips to be created. The fewer strips you have the better.

https://en.wikipedia.org/wiki/Triangle_strip

 EarthQuake said:

If you're not using n-gons while modeling you're making life much harder on yourself. There is absolutely no reason why you can't use n-gons while working. N-gons can be very helpful with sub-d modeling as well, despite some dogmatic claims that you should always use quads.

However, when prepping to export a final assets to game, it's common practice to convert n-gons to quads/tris, just to make sure the exporter (or importer) doesn't make a mess of it.

There is little logical reason to avoid triangles either. I mean, you shouldn't build your entire mesh out of triangles, but some surfaces are best suited to triangles and sticking to quads because of some dogma isn't helpful.

If you want to temporarily create n-gons that's fine. But as you say, when you export it, you should check that they are ok. 
The problem is that explaining the exact use case for n-gons in every situation isn't something you can fit into a forum post. It's much easier to create a tool that checks if you have n-gons and alerts the artist than it is to address every 'ok' use case for n-gons.

Maybe we should have a sticky called "when can I use n-gons" ?