plotboilerplate
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A simple javascript plotting boilerplate for 2d stuff.
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JavaScript
/**
* @modified_by Ikaros Kappler
* @date_init 2012-10-17
* @date 2017-07-31
* @modified 2020-08-17 Ported from vanilla JS to TypeScript.
* @version 2.0.1
**/
import { Triangle } from "../../Triangle";
import { Vertex } from "../../Vertex";
import { Line as Edge } from "../../Line";
// TODO: cleanup? This seems not to be used.
// const EPSILON : number = 1.0e-6;
/**
* @classdesc A Delaunay pointset triangulation implementation. Inspired by
* http://www.travellermap.com/tmp/delaunay.htm
*
* License: Public Domain
* Original C++ code by Joshua Bell
*
* @requires Triangle
* @requires Line
* @requires Vertex
*/
export class Delaunay {
constructor(pointList) {
this.pointList = pointList;
}
triangulate() {
return this.Triangulate(this.pointList);
}
////////////////////////////////////////////////////////////////////////////////
//
// Delaunay Triangulation Code, by Joshua Bell
//
// Inspired by: http://www.codeguru.com/cpp/data/mfc_database/misc/article.php/c8901/
//
// This work is hereby released into the Public Domain. To view a copy of the public
// domain dedication, visit http://creativecommons.org/licenses/publicdomain/ or send
// a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco,
// California, 94105, USA.
//
////////////////////////////////////////////////////////////////////////////////
//------------------------------------------------------------
// Triangulate
//
// Perform the Delaunay Triangulation of a set of vertices.
//
// vertices: Array of Vertex objects
//
// returns: Array of Triangles
//------------------------------------------------------------
Triangulate(vertices) {
const triangles = [];
// First, create a "supertriangle" that bounds all vertices
var st = this.createBoundingTriangle(vertices);
triangles.push(st);
// begin the triangulation one vertex at a time
for (var i in vertices) {
// NOTE: This is O(n^2) - can be optimized by sorting vertices
// along the x-axis and only considering triangles that have
// potentially overlapping circumcircles
this.AddVertex(vertices[i], triangles);
}
// Remove triangles that shared edges with "supertriangle"
for (var i in triangles) {
var triangle = triangles[i];
if (triangle.a == st.a || triangle.a == st.b || triangle.a == st.c ||
triangle.b == st.a || triangle.b == st.b || triangle.b == st.c ||
triangle.c == st.a || triangle.c == st.b || triangle.c == st.c) {
delete triangles[i];
}
}
return triangles;
}
; // Triangulate
// Internal: create a triangle that bounds the given vertices, with room to spare
createBoundingTriangle(vertices) {
// NOTE: There's a bit of a heuristic here. If the bounding triangle
// is too large and you see overflow/underflow errors. If it is too small
// you end up with a non-convex hull.
var minx, miny, maxx, maxy;
for (var i in vertices) {
var vertex = vertices[i];
if (minx === undefined || vertex.x < minx) {
minx = vertex.x;
}
if (miny === undefined || vertex.y < miny) {
miny = vertex.y;
}
if (maxx === undefined || vertex.x > maxx) {
maxx = vertex.x;
}
if (maxy === undefined || vertex.y > maxy) {
maxy = vertex.y;
}
}
var dx = (maxx - minx) * 10;
var dy = (maxy - miny) * 10;
var stv0 = new Vertex(minx - dx, miny - dy * 3);
var stv1 = new Vertex(minx - dx, maxy + dy);
var stv2 = new Vertex(maxx + dx * 3, maxy + dy);
return new Triangle(stv0, stv1, stv2);
}
; // END createBoundingTriangle
// Internal: update triangulation with a vertex
AddVertex(vertex, triangles) {
var edges = [];
// Remove triangles with circumcircles containing the vertex
for (var i in triangles) {
var triangle = triangles[i];
if (triangle.inCircumcircle(vertex)) {
edges.push(new Edge(triangle.a, triangle.b));
edges.push(new Edge(triangle.b, triangle.c));
edges.push(new Edge(triangle.c, triangle.a));
delete triangles[i];
}
}
edges = this.mkUniqueEdges(edges);
// Create new triangles from the unique edges and new vertex
for (var i in edges) {
// console.log( 'adding triangle' );
var edge = edges[i];
triangles.push(new Triangle(edge.a, edge.b, vertex));
}
}
; // END AddVertex
// Internal: remove duplicate edges from an array
mkUniqueEdges(edges) {
// TODO: This is O(n^2), make it O(n) with a hash or some such
const uniqueEdges = [];
for (var i in edges) {
let edge1 = edges[i];
let unique = true;
for (var j in edges) {
if (i != j) {
let edge2 = edges[j];
if ((edge1.a == edge2.a && edge1.b == edge2.b) ||
(edge1.a == edge2.b && edge1.b == edge2.a)) {
unique = false;
break;
}
}
}
if (unique) {
uniqueEdges.push(edge1);
}
}
return uniqueEdges;
}
; // END mkUniqueEdges
}
; // END class
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