spider = edges.map(e => {
let p0 = delaunay.polygons[e[0]],
p1 = delaunay.polygons[e[1]];
for (let i = 0; i < p0.length; i++) {
for (let j = 0; j < p1.length; j++) {
if (
p0[(i + 1) % p0.length] === p1[j] &&
p1[(j + 1) % p1.length] === p0[i]
)
return [p0[i], p1[j]];
}
}
return null;
})