Comment by joefourier

Not go to all “ackchually” but modern GPUs can render in many other ways than rasterising triangles, and they can absolutely draw a cylinder without any tessellation involved. You can use the analytical ray tracing formula, or signed distance fields for a practical way to easily build complex scenes purely with maths: https://iquilezles.org/articles/distfunctions/

Now of course triangles are usually the most practical way to render objects but it just bugs me when someone says something like “Every smooth surface you've ever seen on a screen was actually tiny flat triangles” when it’s patently false, ray tracing a sphere is pretty much the Hello World of computer graphics and no triangles are involved.

Edit: for CADs, direct ray tracing of NURBS surfaces on the GPU exists and lets you render smooth objects with no triangles involved whatsoever, although I’m not sure if any mainstream software uses that method.