to Tri or not to Tri?

se7ered

What's acceptable as far as tri's on my low poly? Should I aim for mostly quads and keep tri's hidden, or should I be super liberal with my tri's to keep my polycount low? What are the benefits of using all quads or quads and tri's other than taking the mesh to zbrush/mudbox?

Stromberg90

Using quads makes it easier to work on the model, but when it comes to game engines it all gets "converted" to tri's so use tri's whenever you want in your lowpoly.
And when you talk about polycount we almost always mean triangles not quads.

Daelus

It's better to triangulate your model entirely before any baking, as the baking program will be treating it as if it were anyway, and if your rendering program triangulates it automatically in a different fashion you'll end up with normal mapping errors from flipped edges in concave faces.

So I always triangulate my low rez model. At least I do now. Use triangles as much as you want, it'll be triangulated in engine. So long as it can still deform correctly you'll be fine.

tharle

its worth noting that in most modern game engines poly count really isnt the bottleneck it used to be. generally texture memory and framerate issues from lighting and pfx etc. are going to be more important so if it's going to save you time and heartache by having a slightly less optimised model with quads rather than tri's do that. you can always come back and optimise things later if it does start causing a problem. imo the main advantages of quads is being able to use edge loops select and add more geometry. in fact it's a lot easier to reduce the poly count of a quadded model than a triangulated one!

Ace-Angel

Triangulating your mesh is only 'feasible' in a few cases, that is when:
A) Your model is very low poly (something like a sign which is a Hexagon, or a Mobile MMO.
You need to correct shading errors because your engine doesn't triangulate a certain mesh correctly.
C) Your normal map bakes are giving you issues.
D) Your Specular is warped on the shading level.

Manually triangulating your model, while laborious, simply isn't worth it in the end. Engine nowadays already triangulate your models pretty well, and the few cases in which they don't usually are associated with N-gons or weird flat shapes that might be too big and relaxed, without even division for the mesh to correctly connect the vertices for a tri.

A model like a character, unless very low-poly and needs manual care, will never require manual triangulation, it's simply too much time spend on nothing at the end of the day. The payoff is too little.

Same with rocks and temples, on the other hand, there is a good chance, large walls say in a gas-station will little extrudes here and there might need triangulation...again, MIGHT need.

Also, while polycounts don't bottleneck games, Vertices do. It doesn't matter if your model is a tri or quads, vertices will add to performance, not to mention UV splits as well smoothing groups.

Optimization wise, I don't understand why Tri's or Quads would be any different in optimization. A Quad based spiral loop on your characters arm is just as bad, if not, worse then a loop that ends with a triangle as a cap-off.

I honestly can recommend one thing, go through Polycounts Wiki, this will answer alot of your questions.