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Modernize voronoi (#557)
Voronoi.js modernization by @SaltyQuetzals * Changed Voronoi generator to be more class-based, added mediocre documentation. * Added spaces to JSDoc links so text doesn't bleed into URL * Found delaunator docs, very helpful in writing function documentation.
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Gabriel Britain
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3 changed files with 123 additions and 69 deletions
4
main.js
4
main.js
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@ -12,7 +12,7 @@ document.title += " v" + version;
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// Switches to disable/enable logging features
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const INFO = 0;
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const TIME = 0;
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const TIME = 1;
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const WARN = 1;
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const ERROR = 1;
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@ -610,7 +610,7 @@ function calculateVoronoi(graph, points) {
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TIME && console.timeEnd("calculateDelaunay");
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TIME && console.time("calculateVoronoi");
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const voronoi = Voronoi(delaunay, allPoints, n);
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const voronoi = new Voronoi(delaunay, allPoints, n);
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graph.cells = voronoi.cells;
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graph.cells.i = n < 65535 ? Uint16Array.from(d3.range(n)) : Uint32Array.from(d3.range(n)); // array of indexes
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graph.vertices = voronoi.vertices;
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@ -394,7 +394,7 @@
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const hull = getHull(start, s.i, s.cells / 10);
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const points = [...hull].map(v => pack.vertices.p[v]);
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const delaunay = Delaunator.from(points);
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const voronoi = Voronoi(delaunay, points, points.length);
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const voronoi = new Voronoi(delaunay, points, points.length);
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const chain = connectCenters(voronoi.vertices, s.pole[1]);
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const relaxed = chain.map(i => voronoi.vertices.p[i]).filter((p, i) => i%15 === 0 || i+1 === chain.length);
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paths.push([s.i, relaxed]);
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@ -1,82 +1,136 @@
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(function (global, factory) {
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typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
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typeof define === 'function' && define.amd ? define(factory) :
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(global.Voronoi = factory());
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}(this, (function () { 'use strict';
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class Voronoi {
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/**
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* Creates a Voronoi diagram from the given Delaunator, a list of points, and the number of points. The Voronoi diagram is constructed using (I think) the {@link https://en.wikipedia.org/wiki/Bowyer%E2%80%93Watson_algorithm |Bowyer-Watson Algorithm}
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* The {@link https://github.com/mapbox/delaunator/ |Delaunator} library uses {@link https://en.wikipedia.org/wiki/Doubly_connected_edge_list |half-edges} to represent the relationship between points and triangles.
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* @param {{triangles: Uint32Array, halfedges: Int32Array}} delaunay A {@link https://github.com/mapbox/delaunator/blob/master/index.js |Delaunator} instance.
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* @param {[number, number][]} points A list of coordinates.
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* @param {number} pointsN The number of points.
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*/
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constructor(delaunay, points, pointsN) {
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this.delaunay = delaunay;
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this.points = points;
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this.pointsN = pointsN;
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this.cells = { v: [], c: [], b: [] }; // voronoi cells: v = cell vertices, c = adjacent cells, b = near-border cell
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this.vertices = { p: [], v: [], c: [] }; // cells vertices: p = vertex coordinates, v = neighboring vertices, c = adjacent cells
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var Voronoi = function Voronoi(delaunay, points, pointsN) {
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const cells = {v: [], c: [], b: []}; // voronoi cells: v = cell vertices, c = adjacent cells, b = near-border cell
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const vertices = {p: [], v: [], c: []}; // cells vertices: p = vertex coordinates, v = neighboring vertices, c = adjacent cells
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for (let e=0; e < delaunay.triangles.length; e++) {
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// Half-edges are the indices into the delaunator outputs:
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// delaunay.triangles[e] gives the point ID where the half-edge starts
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// delaunay.triangles[e] returns either the opposite half-edge in the adjacent triangle, or -1 if there's not an adjacent triangle.
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for (let e = 0; e < this.delaunay.triangles.length; e++) {
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const p = delaunay.triangles[nextHalfedge(e)];
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if (p < pointsN && !cells.c[p]) {
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const edges = edgesAroundPoint(e);
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cells.v[p] = edges.map(e => triangleOfEdge(e)); // cell: adjacent vertex
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cells.c[p] = edges.map(e => delaunay.triangles[e]).filter(c => c < pointsN); // cell: adjacent valid cells
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cells.b[p] = edges.length > cells.c[p].length ? 1 : 0; // cell: is border
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const p = this.delaunay.triangles[this.nextHalfedge(e)];
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if (p < this.pointsN && !this.cells.c[p]) {
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const edges = this.edgesAroundPoint(e);
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this.cells.v[p] = edges.map(e => this.triangleOfEdge(e)); // cell: adjacent vertex
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this.cells.c[p] = edges.map(e => this.delaunay.triangles[e]).filter(c => c < this.pointsN); // cell: adjacent valid cells
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this.cells.b[p] = edges.length > this.cells.c[p].length ? 1 : 0; // cell: is border
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}
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const t = triangleOfEdge(e);
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if (!vertices.p[t]) {
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vertices.p[t] = triangleCenter(t); // vertex: coordinates
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vertices.v[t] = trianglesAdjacentToTriangle(t); // vertex: adjacent vertices
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vertices.c[t] = pointsOfTriangle(t); // vertex: adjacent cells
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const t = this.triangleOfEdge(e);
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if (!this.vertices.p[t]) {
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this.vertices.p[t] = this.triangleCenter(t); // vertex: coordinates
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this.vertices.v[t] = this.trianglesAdjacentToTriangle(t); // vertex: adjacent vertices
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this.vertices.c[t] = this.pointsOfTriangle(t); // vertex: adjacent cells
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}
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}
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function pointsOfTriangle(t) {
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return edgesOfTriangle(t).map(e => delaunay.triangles[e]);
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}
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function trianglesAdjacentToTriangle(t) {
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let triangles = [];
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for (let e of edgesOfTriangle(t)) {
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let opposite = delaunay.halfedges[e];
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triangles.push(triangleOfEdge(opposite));
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}
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return triangles;
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}
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function edgesAroundPoint(start) {
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let result = [], incoming = start;
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do {
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result.push(incoming);
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const outgoing = nextHalfedge(incoming);
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incoming = delaunay.halfedges[outgoing];
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} while (incoming !== -1 && incoming !== start && result.length < 20);
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return result;
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}
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function triangleCenter(t) {
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let vertices = pointsOfTriangle(t).map(p => points[p]);
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return circumcenter(vertices[0], vertices[1], vertices[2]);
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}
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return {cells, vertices}
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}
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function edgesOfTriangle(t) {return [3*t, 3*t+1, 3*t+2];}
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/**
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* Gets the IDs of the points comprising the given triangle. Taken from {@link https://mapbox.github.io/delaunator/#triangle-to-points| the Delaunator docs.}
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* @param {number} t The index of the triangle
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* @returns {[number, number, number]} The IDs of the points comprising the given triangle.
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*/
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pointsOfTriangle(t) {
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return this.edgesOfTriangle(t).map(edge => this.delaunay.triangles[edge]);
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}
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function triangleOfEdge(e) {return Math.floor(e/3);}
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/**
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* Identifies what triangles are adjacent to the given triangle. Taken from {@link https://mapbox.github.io/delaunator/#triangle-to-triangles| the Delaunator docs.}
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* @param {number} t The index of the triangle
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* @returns {number[]} The indices of the triangles that share half-edges with this triangle.
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*/
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trianglesAdjacentToTriangle(t) {
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let triangles = [];
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for (let edge of this.edgesOfTriangle(t)) {
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let opposite = this.delaunay.halfedges[edge];
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triangles.push(this.triangleOfEdge(opposite));
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}
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return triangles;
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}
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function nextHalfedge(e) {return (e % 3 === 2) ? e-2 : e+1;}
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/**
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* Gets the indices of all the incoming and outgoing half-edges that touch the given point. Taken from {@link https://mapbox.github.io/delaunator/#point-to-edges| the Delaunator docs.}
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* @param {number} start The index of an incoming half-edge that leads to the desired point
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* @returns {number[]} The indices of all half-edges (incoming or outgoing) that touch the point.
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*/
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edgesAroundPoint(start) {
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const result = [];
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let incoming = start;
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do {
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result.push(incoming);
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const outgoing = this.nextHalfedge(incoming);
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incoming = this.delaunay.halfedges[outgoing];
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} while (incoming !== -1 && incoming !== start && result.length < 20);
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return result;
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}
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function prevHalfedge(e) {return (e % 3 === 0) ? e+2 : e-1;}
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/**
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* Returns the center of the triangle located at the given index.
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* @param {number} t The index of the triangle
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* @returns {[number, number]}
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*/
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triangleCenter(t) {
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let vertices = this.pointsOfTriangle(t).map(p => this.points[p]);
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return this.circumcenter(vertices[0], vertices[1], vertices[2]);
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}
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function circumcenter(a, b, c) {
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let ad = a[0]*a[0] + a[1]*a[1],
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bd = b[0]*b[0] + b[1]*b[1],
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cd = c[0]*c[0] + c[1]*c[1];
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let D = 2 * (a[0] * (b[1] - c[1]) + b[0] * (c[1] - a[1]) + c[0] * (a[1] - b[1]));
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/**
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* Retrieves all of the half-edges for a specific triangle `t`. Taken from {@link https://mapbox.github.io/delaunator/#edge-and-triangle| the Delaunator docs.}
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* @param {number} t The index of the triangle
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* @returns {[number, number, number]} The edges of the triangle.
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*/
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edgesOfTriangle(t) { return [3 * t, 3 * t + 1, 3 * t + 2]; }
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/**
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* Enables lookup of a triangle, given one of the half-edges of that triangle. Taken from {@link https://mapbox.github.io/delaunator/#edge-and-triangle| the Delaunator docs.}
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* @param {number} e The index of the edge
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* @returns {number} The index of the triangle
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*/
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triangleOfEdge(e) { return Math.floor(e / 3); }
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/**
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* Moves to the next half-edge of a triangle, given the current half-edge's index. Taken from {@link https://mapbox.github.io/delaunator/#edge-to-edges| the Delaunator docs.}
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* @param {number} e The index of the current half edge
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* @returns {number} The index of the next half edge
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*/
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nextHalfedge(e) { return (e % 3 === 2) ? e - 2 : e + 1; }
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/**
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* Moves to the previous half-edge of a triangle, given the current half-edge's index. Taken from {@link https://mapbox.github.io/delaunator/#edge-to-edges| the Delaunator docs.}
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* @param {number} e The index of the current half edge
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* @returns {number} The index of the previous half edge
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*/
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prevHalfedge(e) { return (e % 3 === 0) ? e + 2 : e - 1; }
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/**
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* Finds the circumcenter of the triangle identified by points a, b, and c. Taken from {@link https://en.wikipedia.org/wiki/Circumscribed_circle#Circumcenter_coordinates| Wikipedia}
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* @param {[number, number]} a The coordinates of the first point of the triangle
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* @param {[number, number]} b The coordinates of the second point of the triangle
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* @param {[number, number]} c The coordinates of the third point of the triangle
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* @return {[number, number]} The coordinates of the circumcenter of the triangle.
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*/
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circumcenter(a, b, c) {
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const [ax, ay] = a;
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const [bx, by] = b;
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const [cx, cy] = c;
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const ad = ax * ax + ay * ay;
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const bd = bx * bx + by * by;
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const cd = cx * cx + cy * cy;
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const D = 2 * (ax * (by - cy) + bx * (cy - ay) + cx * (ay - by));
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return [
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Math.floor(1/D * (ad * (b[1] - c[1]) + bd * (c[1] - a[1]) + cd * (a[1] - b[1]))),
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Math.floor(1/D * (ad * (c[0] - b[0]) + bd * (a[0] - c[0]) + cd * (b[0] - a[0])))
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Math.floor(1 / D * (ad * (by - cy) + bd * (cy - ay) + cd * (ay - by))),
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Math.floor(1 / D * (ad * (cx - bx) + bd * (ax - cx) + cd * (bx - ax)))
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];
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}
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return Voronoi;
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})));
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}
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