Topology and ignoring ngons.

Jaik

Hey all,

Struggling to parse some methodologies I am seeing in various tutorials I have been seeing around the web in regards to Ngons and where good topology is necessary and where you can get by without it.

Currently I am watching Vaughan Lings tribot tutorial and I notice that he basically disregards the Ngons that are made during booleans, bevels etc. I know in game models (what I primarily make) good topology and efficiency is key. I have always assumed that this was because of the cost of polycount vs ease of editing and also because Ngons can cause unwanted artifacts when rendering.

However, after watching a number of tutorials based more around using 3D for vis dev and concept art, it seems that it can be ngons galore and there doesnt seem to be much of an issue at render time. 

I was wondering if someone who is much more of an expert than me can categorically explain when you NEED to watch your polys and when it is all right to just move through and not worry about it.

(If there is already a thread on this, would love a link, I just cant think of what to search for to find something)

oglu

a five sided ngon is made out of 3 triangles... just the edges arnt visible...
in the end the engine or renderer will split everything into triangles... some engine are good in handling quad strips...
but most of the time you need quads only to have good deformation for animation...

dont worry to much about your edgeflow... concentrate more on form and design...
if you need good topo for your portfolio just post the model here...

musashidan

For concept art, renderings, whatever. It absolutely doesn't matter. The end result is all that matters. Polysoup topo is fine for this, and there are even arguments for when using n-gons can be beneficial.

However, good topo is expected in a production pipeline. Whether it's for deformation, baking, ease of use for modeling/unwrapping/skinning/etc.

Jaik

Thanks so much for the replies. I assume for game and for film that stays the same. So long as it looks good as a final product, it doesnt matter. But if it needs to be deformed then quads are the go?

AtticusMars

I wouldn't use an n-gon for a deforming game mesh, triangles are alright.

Eric Chadwick

One trouble with using ngons for game models is when the game has to triangulate to render, it may create different triangles than what you see in your modeling app.

You might see concavites where you wanted convexities, or you might get long thin triangles which can cause real-time rendering slowdowns.

Different triangulation also matters when using normal maps, because it can cause some ugly shading artifacts.

http://wiki.polycount.com/wiki/Normal_Map_Modeling
http://wiki.polycount.com/wiki/Topology

sprunghunt

Substance designer and substance painter do not like polygons with more than 4 sides. The on-screen display will have holes in it where you have them and the bakes will look funny.

Zbrush will do weird stuff if you try to import a mesh that's not quads. N-gons are the least predictable in this case in my experience.

So it's not just the game engines that you have to worry about. Generally n-gons should be avoided.

AtticusMars

sprunghunt said:

Zbrush will do weird stuff if you try to import a mesh that's not quads.

I've been hearing this since I started using ZBrush yet I have never had any problems importing meshes with triangles. N-Gons on the other hand get all fucked up, especially on boolean meshes imported from Blender.