Something on the complex plane? A stained glass picture in a window at Gonville & Caius College, Cambridge.

Apollonius of Perga, around 300 BC, wrote a brilliant series of books on conic sections, which, perhaps strangely, did not use the focus-directrix construction. This is his basic construction for an ellipse, equivalent to the equation y² = x-kx² (geogebra.org/geometry/yk4r3…):

I was thinking about a Shadertoy for the Voderberg tiling, but it's much easier to do such tilings with vector graphics using a 2D HTML canvas: matthewarcus.github.io/canvas/tilings/

vec4 sphereFromFourPoints(vec3 a, vec3 b, vec3 c, vec3 d) { a -= d; b -= d; c -= d; a /= dot(a,a); b /= dot(b,b); c /= dot(c,c); vec3 n = cross(c-a,c-b); vec3 p = dot(a,n)/dot(n,n)*n; p /= dot(p,p); vec3 centre = 0.5*p; return vec4(centre+d,length(centre)); }

Some variations of Pascal's hexagon, where one or more pairs of points have merged so a hexagon line becomes a tangent:

I passed Polygon Road in Camden the other day, which turns out to be quite interesting, according to diamond geezer: diamondgeezer.blogspot.com/2024/02/polygo…

Euclid in Syriac, from the new exhibition at Cambridge University Library. x.com/theUL/status/1…