system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are low poly 3D models made of triangles and not squares/rectangles?
gpt
In the early days rectangles *were* used. A games console in the late 90's rendered everything with rectangles.
However, that was a really bad idea, and triangles are much nicer to work with for a couple of reasons.

First, of course, you can easily make a rectangle out of a pair of triangles *anyway*, so you're not really losing out on anything by using triagles. At worst you'll have twice as many of them. But the trade-off is that they're simpler to work with, so that's really ok.

But the main advantage of triangles is that they are *always* flat. If you pick three random points in a 3d space, you can *always* connect them and the result will be lie on a flat plane. That means you can connect these three points, and know you'll get a straightforward triangle.

If you pick four points at random, you probably won't be able to connect them into a rectangle at all. The four points probably won't lie on a plane, and it's not really obvious what shape would be created if you tried to connect them. It woudl depend on *how* you connect them.

So if you're working with rectangles, you have to constantly watch out for these "broken" shapes and that's just a lot of extra work.

Computers like working really fast with really simple things. And triangles are great for that.