re-poly2tri
v1.5.1
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A 2D constrained Delaunay triangulation library
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poly2tri.js
Based on the paper "Sweep-line algorithm for constrained Delaunay triangulation" by V. Domiter and and B. Zalik
Poly2Tri Copyright (c) 2009-2014, Poly2Tri Contributors
http://code.google.com/p/poly2tri/
poly2tri.js (JavaScript port) (c) 2009-2017, Poly2Tri Contributors
https://github.com/r3mi/poly2tri.js
This document describes the JavaScript version of poly2tri. Officially supported languages are C++ and Java : poly2tri.js is a community based port, currently based on the "May 1, 2013" C++ version, with patches and JavaScript specificities. You can ask support in the forum.
poly2tri.js is distributed with the same license as other poly2tri ports : the revised BSD License (3-clause BSD), see license.
Before using
Since there are no input validation of the data given for triangulation you need to think about this. poly2tri does not support repeated points within epsilon.
- If you have a cyclic function that generates random points make sure you don't add the same coordinate twice,
- If you are given input and aren't sure same point exist twice you need to check for this yourself,
- Only simple polygons are supported. You may add holes or interior Steiner points,
- Interior holes must not touch other holes, nor touch the polyline boundary,
- Use the library as described in the next paragraph.
Make sure you understand the preceding notice before posting an issue. If you have an issue not covered by the above, include your data-set with the problem.
If you want to triangulate complex or weak polygons, you will need to prepare your data with a polygon clipping library like Javascript Clipper.
You can test your dataset using the online JavaScript demo.
The only easy day was yesterday; have a nice day. -- Mason Green
Install
This module works on both Node.js and browsers.
For Node.js:
For TypeScript: poly2tri types (poly2tri.d.ts
) are now directly bundled inside the NPM package,
so that they can automatically be consumed from TypeScript applications.
You do not need to install types separately from DefinitelyTyped
or @types
anymore.
For browsers, using Bower:
bower install --save poly2tri
For browsers, manually:
wget http://r3mi.github.io/poly2tri.js/dist/poly2tri.js
The file dist/poly2tri.js
can be included directly.
It is standalone and has no mandatory dependency.
Use dist/poly2tri.min.js
for the compressed version.
Usage
Get a reference to the library. Thanks to browserify, the module is in UMD format (Universal Module Definition), compatible with the various module systems:
CommonJS:
var poly2tri = require('poly2tri');
TypeScript:
import * as poly2tri from 'poly2tri';
RequireJS:
require('poly2tri', function (poly2tri) { ... });
If you are not using a module system at all, you can access the package as a global variable
poly2tri
(orwindow.poly2tri
in a browser).
Initialize CDT with a simple polyline (this defines the constrained edges)
var contour = [ new poly2tri.Point(100, 100), new poly2tri.Point(100, 300), new poly2tri.Point(300, 300), new poly2tri.Point(300, 100) ]; var swctx = new poly2tri.SweepContext(contour);
Add holes if necessary (also simple polylines)
var hole = [ new poly2tri.Point(200, 200), new poly2tri.Point(200, 250), new poly2tri.Point(250, 250) ]; swctx.addHole(hole); // or swctx.addHoles([hole1, hole2]) for multiple holes
Add Steiner points if necessary
var point = new poly2tri.Point(150, 150); swctx.addPoint(point); // or swctx.addPoints([p1, p2, p3]) for multiple points
Triangulate
swctx.triangulate(); var triangles = swctx.getTriangles();
Use results
triangles.forEach(function(t) { t.getPoints().forEach(function(p) { console.log(p.x, p.y); }); // or t.getPoint(0), t.getPoint(1), t.getPoint(2) });
See index.html
for a complete example.
Method calls can be chained:
var triangles = swctx.addHoles(holes).addPoints(points).triangulate().getTriangles();
Advanced Options
Error handling
The library methods throw an exception for invalid input data,
such as duplicated or collinear points.
The exception object will contain a points
array attribute with the
faulty data, if available.
Custom Point class
poly2tri.js supports using custom point class instead of poly2tri.Point
.
Any "Point like" object with {x, y}
attributes is supported
to initialize the SweepContext polylines and points
(duck typing).
var contour = [{x:100, y:100}, {x:100, y:300}, {x:300, y:300}, {x:300, y:100}];
var swctx = new poly2tri.SweepContext(contour);
poly2tri.js might add extra fields to the point objects when computing the
triangulation : they are prefixed with _p2t_
to avoid collisions
with fields in the custom class.
Custom Point fields
The output triangles in getTriangles()
have vertices which are references
to the initial input points (not copies). Any custom fields in the
initial points can be retrieved in the output triangles.
var contour = [{x:100, y:100, id:1}, {x:100, y:300, id:2}, {x:300, y:300, id:3}];
var swctx = new poly2tri.SweepContext(contour);
swctx.triangulate();
var triangles = swctx.getTriangles();
typeof triangles[0].getPoint(0).id
// → "number"
poly2tri.noConflict
Reverts the poly2tri
global object back to its original value,
and returns a reference to this poly2tri
object.
var p = poly2tri.noConflict();
Displaying the samples
Install the dependent packages by running:
bower install
Use index.html
(also available online as a demo) to display the result of a triangulation.
Polygon contour, holes, and Steiner points can be added.
Use any separator between points, e.g.
100 100
[100, 300, 300, 300]
(300;100)
is valid data to describe 4 points.
Some interesting samples can be interactively loaded
using the "Load preset data" option menu.
You can get additional files from the tests/data
directory.
You need a modern browser to draw the results, supporting the HTML5 <canvas>
.
Development
Install the dependent packages by running:
npm install
Build the release code in dist/
(library and demo) using:
npm run build
# or safer: npm run test
The automated tests are built using jasmine, both for browser and for Node.js testing. Run the headless tests (JSHint, Node.js and PhantomJS) with:
npm test
Run all the browser tests (PhantomJS, Firefox, Safari and Chrome) with:
npm run test.browsers
Check JSHint and TSLint with:
npm run check
Performance tests
This jsPerf compares the performances across several versions of the module.
You can also run
npm run bench