Why to choose Faces or Tris for modeling? Pros vs Cons?
node
Hello there, I had a question about Faces and Tris in 3D Modeling. I understand the difference between them in the sense of what they are.
What i am confused about is:
-Whats the difference to using them?
-Are there advantages/disadvantages to using one over the other?
-When modeling should I be watching my Face count or my Tri count?
-Is one better for optimization in an engine than the other one?
Thanks again for taking the time to review my question friends. Cheers.
What i am confused about is:
-Whats the difference to using them?
-Are there advantages/disadvantages to using one over the other?
-When modeling should I be watching my Face count or my Tri count?
-Is one better for optimization in an engine than the other one?
Thanks again for taking the time to review my question friends. Cheers.
Replies
EDIT (to be more helpful and not only seem smug):
Quads are generally more flexible and are what modeling tools are designed around. With quads you can easily add or remove edge loops, which isn't possible with tris.
-Are there advantages/disadvantages to using one over the other?
Generally, you should be using both. Mostly quads, but triangles where necessary.
-When modeling should I be watching my Face count or my Tri count?
Don't matter much as long as you are consistent.
-Is one better for optimization in an engine than the other one?
By the time the GPU renders a 3d object, everything is converted to tris. You should convert the model to tris before baking the normal map. But keep a quad version of the model in case you need to change anything.
ngons are fine. just another tool in the toolbox.
There are specific names for polygons that have more than 5 sides:
5 pentagon
6 hexagon
7 heptagon
8 octagon
n = an indeterminate number, ngon.
How many gons? I don't know and I don't care, there are too many to count. There are "n" number of gons. It is an ngon. Usually after 8 sides (octagon) the shape becomes so rounded it's hard to tell and people just give up and call them ngons.
Triangle modeling gets extremely tedious really fast on anything other than extremely low poly models. anything more than 500 tris is going to be a pain to tri-model. Quads let you work in edge loops and rings, which opens the door to a lot of techniques and tools.
Actually... If you want to be exact, you should be paying attention to total vert count which also includes extra verts from UV seams and smoothing breaks. Ballparking with tris is probably fine for most objects in most game engines, just don't do anything stupid like facet a model or make every edge a seam and you should be fine. Just know that your model is a cloud of verts and a lot of operations run over verts, mostly transforms and shaders. Faces are just drawn between verts, almost as an after thought.
For example Substance Designer will display n-gons as empty space. For any kind of real-time application n-gons are bad.
You should watch your vertex count. Vertexes are what take up memory not tris. And the vertex count varies quite a bit by how many edge splits you have. A low vertex-to-poly ratio is as sign of a clean model.
It's not a big deal to avoid using n-gons so I'll probably keep going that way out of habit, but some programs (like Zbrush I'm pretty sure), will complain if you import a model with n-gons. So what's that about?
- quads are easier to edit around, create loops and whatnot. USE BOTH!
- your in engine vertex count (don't trust max or maya). triangle count gives you an idea, poly count is useless
- everything becomes triangles in the end
reading material:
http://www.ericchadwick.com/examples/provost/byf1.html
http://www.ericchadwick.com/examples/provost/byf2.html
https://simonschreibt.de/gat/renderhell/
http://www.fragmentbuffer.com/gpu-performance-for-game-artists/
http://wiki.polycount.com/wiki/Limb_Topology
The problem with any polygon that isn't a tri is that you have to convert to a triangle to display it. This doesn't matter if the polygon is planar but if you have a non-planar polygon it can have several states depending on how it is triangulated. Here's some examples:
The two planes in the upper right are exactly the same number of vertexes but are triangulated in a different way. Below you can see a N-gon which is triangluated in two different ways. You can see that the wedge in the middle disappears in one example.
This is correct?
I still can't believe how prevalent the N-gon myth is among newcomers to modeling(and many experienced modelers, it seems) The N-gon is like a poor bastard who was falsely accused of rape as a teenager, entirely cleared by the justice system, but whose life is utterly ruined by the accusation of 20 years ago.....
Using N-gons is vital to my hard-surface workflow. They allow me to model complex shapes very quickly. Then it's just a matter of adding a Turn to Poly modifier non-destructively to triangulate the mesh before export to bake/engine. Once you know how to place a few strategic edges to control the auto-triangulation and avoid extreme tris/shading artifacts then you're golden.
Even when sub-dividing the same applies as above. I use shitloads of N-gons. And again, once you know where to place a few edges at certain places on the topology to avoid artifacts, and a non-destructive chamfer/subdivide modifier, life is good. The sub-D mesh(in our case as game artists) is solely to bake from. If it looks good and smooths well.......then perfect.
All N-gons ultimately become quads when subdivided: 5x4=20/6x4=24/7x4=28.........and on and on.
A quick note about that, not all apps handle non-visible edges the same way, max lets you flip them any way you would like, other apps force non-visible edges to flow in a certain direction, others go the opposite.
Case in point, all the stuff you've explained about your hard surface workflow -- I've been modeling all day every day for about 8 months now, and not much of that made sense to me. But I know enough that I could figure it out and make sense of it with a little research, but if you had tried to explain that to me 6 months ago it would be like trying to train a cat. For beginners, simple rules I suppose have a place just to get you going and avoiding things that could be bad habits if you don't understand how the background processes work.
I spent years learning sub-d modeling for offline rendering/animation before I got into game art and laugh now at all those hours I spent re-routing edgeloops and stressing out over 6-valance poles and the fact that I had an extra vert that was not quad-compliant.
But it definitely had its merits as I obsessed about it that much that it gave me a very solid foundation and understanding of topology.
These days I have since become quad-agnostic and lay daily offerings at the shrine of N-gon.
That if you're looking forward to animate or use blend shapes on your character or model, it is better to use quads over n-gons or triangles. As the topology will move better if it's made up of quads, but that's mostly for characters.
Also, I've been told that all-in-all, game engines triangulate your models on import. So, it's better to use quads, because the engine would automatically triangulate your mesh, which might lead to errors or weird topology if they are n-gons.
Although, I'm not completely sure of the information I've passed on, if I've made any mistake please point it out.
Real-time engines do render triangles. Locking in your triangulation before baking and export to engine is standard. But this can be non-destructive with Max's Turn to poly modifier, for instance.
So yes, quads have their benefits for certain. But so do tris and n-gons. The point here is to understand and know why and when to use each, rather than blindly following a mantra. Perfect example featured in the image at the top of this thread. Nicely presented, but full of bullshit.