fourdjs/layer600cell.js

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import * as POLYTOPES from './polytopes.js';
// face detection for the 600-cell
export function nodes_links(links, nodeid) {
return links.filter((l) => l.source === nodeid || l.target === nodeid);
}
export function linked(links, n1, n2) {
const ls = nodes_links(nodes_links(links, n1), n2);
if( ls.length ) {
return ls[0]
} else {
return false;
}
}
function fingerprint(ids) {
const sids = [...ids];
sids.sort();
return sids.join(',');
}
export function make_600cell() {
const nodes = POLYTOPES.make_600cell_vertices();
const links = POLYTOPES.auto_detect_edges(nodes, 12);
return {
nodes: nodes,
links: links
}
}
export function link_to_tetras(nodes, links, link) {
const n1 = link.source;
const n2 = link.target;
const nl1 = nodes_links(links, n1).filter((l) => l.id !== link.id);
const nl2 = nodes_links(links, n2).filter((l) => l.id !== link.id);
const p1 = new Set();
const p = new Set();
for( const nl of nl1 ) {
if( nl.source !== n1 ) {
p1.add(nl.source);
}
if( nl.target !== n1 ) {
p1.add(nl.target);
}
}
for( const nl of nl2 ) {
if( nl.source !== n2 && p1.has(nl.source) ) {
p.add(nl.source);
}
if( nl.target !== n2 && p1.has(nl.target) ) {
p.add(nl.target);
}
}
const lp = Array.from(p);
const seen = {};
const tetras = [];
for( const p1 of lp ) {
for( const p2 of lp ) {
if( p1 != p2 ) {
if( linked(links, p1, p2) ) {
const fp = fingerprint([n1, n2, p1, p2]);
if( !seen[fp] ) {
seen[fp] = true;
tetras.push({fingerprint: fp, nodes: [n1, n2, p1, p2]})
}
}
}
}
}
return tetras;
}
export function auto_600cell_cells(nodes, links) {
const seen = {};
const tetras = [];
links.map((link) => {
link_to_tetras(nodes, links, link).map((lt) => {
if( !seen[lt.fingerprint] ) {
seen[lt.fingerprint] = true;
tetras.push(lt.nodes);
}
})
});
return tetras;
}
function node_by_id(nodes, nid) {
const ns = nodes.filter((n) => n.id === nid);
return ns[0];
}
export function tetra_w(nodes, tetra) {
let w = 0;
for( const nid of tetra ) {
const node = node_by_id(nodes, nid);
w += node.w;
}
return w / 4;
}
export function sorted_600cells() {
const cell600 = make_600cell();
const tetras = auto_600cell_cells(cell600.nodes, cell600.links);
const layers = tetras.map((t) => { return { "nodes": t, w: tetra_w(cell600.nodes, t) } });
layers.sort((a, b) => b.w - a.w);
return layers;
}
// const cell600 = make_600cell();
// const layers = sorted_600cells(cell600.nodes, cell600.links);
// for( const cell of layers ) {
// // const fp = fingerprint(cell.nodes);
// console.log(`${cell.w} ${cell.nodes}`);
// }
export function make_layered_600cell() {
const tetras = sorted_600cells()
const LAYERS = [
[ "00", 20 ],
[ "01", 20 ],
[ "02", 30 ],
[ "03", 60 ],
[ "04", 60 ],
[ "05", 60 ],
[ "06", 20 ],
[ "07", 60 ],
[ "08", 20 ],
[ "09", 60 ],
[ "10", 60 ],
[ "11", 60 ],
[ "12", 30 ],
[ "13", 20 ],
[ "14", 20 ]
];
const vertices = {};
const seen = {};
let i = 0;
for( const layer of LAYERS ) {
const label = layer[0];
const n = layer[1];
vertices[label] = [];
console.log(`Layer ${label} starting at ${i}`);
for( const t of tetras.slice(i, i + n) ) {
console.log(t);
for( const n of t.nodes ) {
if( !seen[n] ) {
vertices[label].push(n);
seen[n] = true;
}
}
}
i += n;
}
return JSON.stringify(vertices);
}