Awesome
Delaunator
An incredibly fast and robust JavaScript library for Delaunay triangulation of 2D points.
<img src="delaunator.png" alt="Delaunay triangulation example" width="600" />Projects based on Delaunator
- d3-delaunay for Voronoi diagrams, search, traversal and rendering (a part of D3).
- d3-geo-voronoi for Delaunay triangulations and Voronoi diagrams on a sphere (e.g. for geographic locations).
Example
const coords = [168,180, 168,178, 168,179, 168,181, 168,183, ...];
const delaunay = new Delaunator(coords);
console.log(delaunay.triangles);
// [623, 636, 619, 636, 444, 619, ...]
Install
Install with NPM (npm install delaunator
) or Yarn (yarn add delaunator
), then import as an ES module:
import Delaunator from 'delaunator';
To use as a module in a browser:
<script type="module">
import Delaunator from 'https://cdn.skypack.dev/delaunator@5.0.0';
</script>
Or use a browser UMD build that exposes a Delaunator
global variable:
<script src="https://unpkg.com/delaunator@5.0.0/delaunator.min.js"></script>
API Reference
new Delaunator(coords)
Constructs a delaunay triangulation object given an array of point coordinates of the form:
[x0, y0, x1, y1, ...]
(use a typed array for best performance).
Delaunator.from(points[, getX, getY])
Constructs a delaunay triangulation object given an array of points ([x, y]
by default).
getX
and getY
are optional functions of the form (point) => value
for custom point formats.
Duplicate points are skipped.
delaunay.triangles
A Uint32Array
array of triangle vertex indices (each group of three numbers forms a triangle).
All triangles are directed counterclockwise.
To get the coordinates of all triangles, use:
for (let i = 0; i < triangles.length; i += 3) {
coordinates.push([
points[triangles[i]],
points[triangles[i + 1]],
points[triangles[i + 2]]
]);
}
delaunay.halfedges
A Int32Array
array of triangle half-edge indices that allows you to traverse the triangulation.
i
-th half-edge in the array corresponds to vertex triangles[i]
the half-edge is coming from.
halfedges[i]
is the index of a twin half-edge in an adjacent triangle
(or -1
for outer half-edges on the convex hull).
The flat array-based data structures might be counterintuitive, but they're one of the key reasons this library is fast.
delaunay.hull
A Uint32Array
array of indices that reference points on the convex hull of the input data, counter-clockwise.
delaunay.coords
An array of input coordinates in the form [x0, y0, x1, y1, ....]
,
of the type provided in the constructor (or Float64Array
if you used Delaunator.from
).
delaunay.update()
Updates the triangulation if you modified delaunay.coords
values in place, avoiding expensive memory allocations.
Useful for iterative relaxation algorithms such as Lloyd's.
Performance
Benchmark results against other Delaunay JS libraries
(npm run bench
on Macbook Pro Retina 15" 2017, Node v10.10.0):
uniform 100k | gauss 100k | grid 100k | degen 100k | uniform 1 million | gauss 1 million | grid 1 million | degen 1 million | |
---|---|---|---|---|---|---|---|---|
delaunator | 82ms | 61ms | 66ms | 25ms | 1.07s | 950ms | 830ms | 278ms |
faster‑delaunay | 473ms | 411ms | 272ms | 68ms | 4.27s | 4.62s | 4.3s | 810ms |
incremental‑delaunay | 547ms | 505ms | 172ms | 528ms | 5.9s | 6.08s | 2.11s | 6.09s |
d3‑voronoi | 972ms | 909ms | 358ms | 720ms | 15.04s | 13.86s | 5.55s | 11.13s |
delaunay‑fast | 3.8s | 4s | 12.57s | timeout | 132s | 138s | 399s | timeout |
delaunay | 4.85s | 5.73s | 15.05s | timeout | 156s | 178s | 326s | timeout |
delaunay‑triangulate | 2.24s | 2.04s | OOM | 1.51s | OOM | OOM | OOM | OOM |
cdt2d | 45s | 51s | 118s | 17s | timeout | timeout | timeout | timeout |
Papers
The algorithm is based on ideas from the following papers:
- A simple sweep-line Delaunay triangulation algorithm, 2013, Liu Yonghe, Feng Jinming and Shao Yuehong
- S-hull: a fast radial sweep-hull routine for Delaunay triangulation, 2010, David Sinclair
- A faster circle-sweep Delaunay triangulation algorithm, 2011, Ahmad Biniaz and Gholamhossein Dastghaibyfard
Robustness
Delaunator should produce valid output even on highly degenerate input. It does so by depending on robust-predicates, a modern port of Jonathan Shewchuk's robust geometric predicates, an industry standard in computational geometry.
Ports to other languages
- delaunator-rs (Rust)
- fogleman/delaunay (Go)
- delaunator-cpp (C++)
- delaunator-sharp (C#)
- delaunator-ruby (Ruby)
- Delaunator-Python (Python)
- ricardomatias/delaunator (Kotlin)
- delaunator-java (Java)
- delaunay-Stata (Stata/Mata)
- Delaunator.jl (Julia)