How GPUs Render Curved Surfaces Through Triangle Tessellation

Your GPU doesn't know what a cylinder is. It knows triangles! That's it. Three points, maybe a color. The entire vocabulary of graphics hardware fits on an index card.

So before any curved surface can be rendered, someone has to chop it into triangles. Lots of them! Arranged just right so the illusion holds. That's tessellation.

A triangle mesh is just two arrays: vertices: [x₀, y₀, z₀, x₁, y₁, z₁, x₂, y₂, z₂, ...] indices: [0, 1, 2, 0, 2, 3, ...]

Vertices are points in space, and indices say which three points form each triangle. That's the entire data structure.