Tris vs Quads for videogames

[skinner92]

Huge THANK YOU for sharing this course, Kent.

I have a question. Regarding Game Dev, would it be better to build a model using Tris or Quads? And why?

When should I avoid Ngons?

[Matthew Fricker]

Game engines always convert your mesh to tris when you import them regardless of how you have modeled your project. 

In a low poly workflow or game model , tris and n-gons are not an issue , but for a high poly piece , specifically one that will use a subsurface modifier , it is important that you stick to quads since the subsurf mod will not work well with tris or n-gons due to the way it works. 

As far as I am aware , any n-gon can be split into tris so you don’t have to worry too much when modelling for games. 

Another thing to watch for when modelling are poles (more than 4 edges meeting at a vert) as that can also cause subsurf errors and cause deformation issues on organic models that are rigged to move such as humans and animals. 

[Keith]

I haven’t delved into making assets for current engines; but I do remember the discussion of modeling in quads and triangulating the model inside the modeler, rather than leaving it up to the game engine.  Most of the time it works out fine; but there are occassions where the game engine gets it wrong, and errors occur.  Of course things may have improved since then, and the above may be a mute point now.  I was also always told to stay away from N-Gons and model only in Quads.  Again, could be wrong.

[Kent Trammell]

You have the same general understanding that I do. AFAIK all 3D programs and renderers convert quads and n-gons to triangles in the end (even if behind the scenes, unseen to the user). For n-gons its a total guess as to how it will be converted (almost never ideal) and for quads there’s two options for converted to tris (either diagonal). Sometimes one diagonal is great and the other awful depending on the model. That’s why game artists are mindful of converting to triangles by hand.

All of this is especially important for lo-res situations. However as game technology advances and gets ever closer to eclipsing non-game tech, like supporting billions of polygons, triangles will likely get less and less consequential.

[Keith]

Yep.  The last time I made anything for an engine, was for Torque and FPSCreator (a small no-coding needed gamemaker, from a company called “The Game Creators”…who now have a program called “GameGuru”).  Back then all I had was a diffuse (now albedo) texture, after UV Mapping.  I never really delved into bump mapping, at the time.  I guess I’ll find out soon though, as I plan on getting back into things.  I’ll just have to be sure to get with the times, and all the juicy advances!

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