"use strict" module.exports = planarDual var compareAngle = require("compare-angle") function planarDual(cells, positions) { var numVertices = positions.length|0 var numEdges = cells.length var adj = [new Array(numVertices), new Array(numVertices)] for(var i=0; i 0) { nextCell = adj[i][b][0] nextDir = i break } } nextVertex = nextCell[nextDir^1] for(var dir=0; dir<2; ++dir) { var nbhd = adj[dir][b] for(var k=0; k 0) { nextCell = e nextVertex = p nextDir = dir } } } if(noCut) { return nextVertex } if(nextCell) { cut(nextCell, nextDir) } return nextVertex } function extractCycle(v, dir) { var e0 = adj[dir][v][0] var cycle = [v] cut(e0, dir) var u = e0[dir^1] var d0 = dir while(true) { while(u !== v) { cycle.push(u) u = next(cycle[cycle.length-2], u, false) } if(adj[0][v].length + adj[1][v].length === 0) { break } var a = cycle[cycle.length-1] var b = v var c = cycle[1] var d = next(a, b, true) if(compareAngle(positions[a], positions[b], positions[c], positions[d]) < 0) { break } cycle.push(v) u = next(a, b) } return cycle } function shouldGlue(pcycle, ncycle) { return (ncycle[1] === ncycle[ncycle.length-1]) } for(var i=0; i 0) { var ni = adj[0][i].length var ncycle = extractCycle(i,j) if(shouldGlue(pcycle, ncycle)) { //Glue together trivial cycles pcycle.push.apply(pcycle, ncycle) } else { if(pcycle.length > 0) { cycles.push(pcycle) } pcycle = ncycle } } if(pcycle.length > 0) { cycles.push(pcycle) } } } //Combine paths and loops together return cycles }