We’re always told to stay away from tri’s and to stick to modeling quad typologies – but what does this mean, and why? And are tri’s always bad even if we can’t avoid them?
The truth is, there are times when modeling with quads are better, like when we want to smooth or animate our model. But, there are times when modeling with tri’s are better – like with low-poly modeling and modeling game design assets.
After reading the steps below you will know exactly where each typology fits in 3D modeling and when to use either one. We’re going to outline, quite plainly, which is best when. But first:
What Are Tri’s and What are Quads?
Tri or Triangle is a simple three-sided polygon with exactly three vertices and three edges. While a Quad or Quadrilateral Polygon is a four-sided polygon with 4 vertices and 4 edges.
When are Quads Better?
- When you are planning to animate. Quads animate better when rigged and being deformed by bones. It’s necessary to have clean topology for modeling and rigging and animating a model so that your mesh can be associated with the correct quads and tris. Rigging with an unclean topology will result in your final animation being unclean and deformed as well.
- When you are planning to model using loop cuts. Loop cuts do not work as well on tri’s as they do on quads- and they come in super handy when modeling. Loop cuts save a ton of time and are something I personally use it in almost every single thing I model. The plus side to modeling with quads from the very beginning is the ability to introduce shortcuts like these. Quads are generally more flexible and are what modeling tools are designed around.
- When you’re looking for clean straight edges. When you want to model something with perfectly straight edges that run at right angles than using quads will benefit you. Introducing tri’s with this outcome in mind can become tricky because you’ll be introducing angles that aren’t 90 degrees. For example, triangles that have one short and two very long edges can cause problems.
- When you want to subdivide. Quads allow you to subdivide. You cant subdivide a tri without exponentially affecting your polycount. Sticking with quads will give you a predictable output when you subdivide.
- It’s easier to UV unwrap quads. Similar to the straight edge problem, when you model using tri’s, you introduce angles that arent 90 degrees. And then when you UV unwrap your mesh it won’t look clean and easily definable. Quad topology is much better to judge and to work at because there are half as many edges in the way.
- If you are planning to smooth your model. if you model your object with quads, you get smoother surfaces. Tris cause issues when smoothing because of the extra vertices and edges. Triangles will often create visible anomalies on the mesh surface when smoothing (using Set Smooth) and when using a Subsurf modifier. When placed in the midst of quads (even number of vertices), the triangles cause a “blemish” on the surface and when animating the mesh, they often cause pinching effects.
- If you are modeling anything complex. Triangle modeling gets extremely tedious really fast on anything other than extremely low poly models.
When Are Tri’s Better?
- When you are making a low poly model. If you’re going to animate your low poly model you still might encounter some problems, but if you’re just making a low poly model for a render, then using triangles shouldn’t get you in too much trouble.
- When you are modeling game assets. Here’s the thing – when you export your model to a game engine (Unity or Unreal Engine), your model will automatically be converted to triangle typology anyway. And this is the reason why many artists will argue that modeling using triangles from the beginning shouldn’t be a big deal. But if you think of it in the way that a quad is essentially two triangles, then you will be able to see why modeling in quads is better in the beginning. There are just simply way more benefits for modeling with quads.
- If you are looking for a quick render. Triangles have some properties that are used for calculation and rendering the images. For example, triangles form always a convex area, the order of the vertices defines the direction of the normal and so on. So, tris are great for implementing fast rendering processes on graphics hardware.
- When you are fixing n-gons. Triangles are a little more lenient and not as bad as n-gons, they still can cause some issue at animation time. But in general, you would rather have a triangle than an n-gon, so don’t feel bad for using them where you absolutely need to.
- If you are making “hard” surface models, architecture, etc. These types of 3D models generally won’t need to be animated across the surface of their mesh-like a character’s face, so, a lot of the potential problems that triangles can cause are not encountered. However, I have run into a few instances with shading problems this way. Your hard surface model will look perfectly fine in your viewport, but when you render, the shading will look off. Tris will be fine for parts of the model the viewer might not see, but be sure no shading problems have occurred.
So, What’s Better Over-all?
Generally, you should be using both. Mostly quads, but triangles where necessary. It will be advised that you stick to quad modeling for a clean model, even when making game assets. Your quad typology model will be converted to a tri model when exported to the game engine you are using. Game engines are for the final result. But your modeler is for making the graphics.
As always, when modeling any typology, you should be paying attention to total vert count which also includes extra vertices from UV seams and smoothing breaks. The smaller your vertices and face count, the better your model will operate and render in the end.
