# Torus > [[PORTAL_Cellular_automaton|Cellular automaton]] spine. ## Microsims — three.js <div class="microsim-player"> <iframe src="https://wikitube-3d-microsims.netlify.app/torus_microsim.html" width="100%" height="520" frameborder="0" loading="lazy" sandbox="allow-scripts allow-same-origin" title="Torus — three.js microsim"></iframe> </div> <p class="wt-pending"><strong>Note:</strong> staged, awaiting CDN deploy — a Geometry-lane three.js asset, reused here since the torus is a tree-verified child of [[PORTAL_Cellular_automaton]].</p> A torus is the donut-shaped surface swept out by rotating a circle around an axis that does not intersect it — topologically, a surface with a single hole through the middle and genus one. It is the standard example of a closed surface that is not simply connected: a loop drawn around the hole cannot be shrunk to a point without leaving the surface. ## Overview This build renders the torus in 3D with its two independent radii — the tube radius and the radius from the centre of the hole — adjustable directly, so the transition from a thin ring to a thick, almost sphere-like donut is visible as a continuous deformation. The torus's most direct connection to this hub is practical rather than decorative: a two-dimensional [[Cellular_automaton|cellular automaton]] grid is very commonly given toroidal (wrapped) boundary conditions, exactly as [[Conway's_Game_of_Life|Conway's Game of Life]] does, so that a glider or other pattern leaving one edge of the grid reappears on the opposite edge — the finite grid is, topologically, a torus, even though it is normally drawn flat. **On the spine:** [[Cellular_automaton]] · [[Conway's_Game_of_Life]] · [[Hypercube]] · [[Hexagonal_tiling]]. ## Wikipedia : Wikitube **Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Torus) : [Wikitube](https://en.wikitube.io/wiki/Torus) --- *Repopulated 2026-08-05 · existing three.js asset renamed + wired, Wikipedia-sourced overview · 0 deletions.*