82 lines
1.5 KiB
JavaScript
82 lines
1.5 KiB
JavaScript
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import * as POLYTOPES from './polytopes.js';
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// face detection for the 600-cell
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export function nodes_links(links, nodeid) {
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return links.filter((l) => l.source === nodeid || l.target === nodeid);
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}
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export function linked(links, n1, n2) {
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const ls = nodes_links(nodes_links(links, n1), n2);
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if( ls.length ) {
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return ls[0]
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} else {
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return false;
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}
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}
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function fingerprint(ids) {
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const sids = [...ids];
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sids.sort();
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return sids.join(',');
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}
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export function make_600cell() {
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const nodes = POLYTOPES.make_600cell_vertices();
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const links = POLYTOPES.auto_detect_edges(nodes, 12);
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return {
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nodes: nodes,
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links: links
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}
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}
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export function link_to_tetras(nodes, links, link) {
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const n1 = link.source;
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const n2 = link.target;
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const nl1 = nodes_links(links, n1).filter((l) => l.id !== link.id);
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const nl2 = nodes_links(links, n2).filter((l) => l.id !== link.id);
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const p1 = new Set();
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const p = new Set();
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for( const nl of nl1 ) {
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if( nl.source !== n1 ) {
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p1.add(nl.source);
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}
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if( nl.target !== n1 ) {
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p1.add(nl.target);
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}
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}
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for( const nl of nl2 ) {
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if( nl.source !== n2 && p1.has(nl.source) ) {
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p.add(nl.source);
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}
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if( nl.target !== n2 && p1.has(nl.target) ) {
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p.add(nl.target);
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}
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}
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const lp = Array.from(p);
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const seen = {};
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const tetras = [];
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for( const p1 of lp ) {
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for( const p2 of lp ) {
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if( p1 != p2 ) {
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if( linked(links, p1, p2) ) {
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const fp = fingerprint([n1, n2, p1, p2]);
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if( !seen[fp] ) {
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seen[fp] = true;
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tetras.push([n1, n2, p1, p2])
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}
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}
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}
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}
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}
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return tetras;
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}
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