Add d3-polygon.

README.md

@@ -22,6 +22,7 @@ If you use NPM, `npm install d3@4.0.0-alpha.4`. Otherwise, download the [latest
 * [Interpolators](#interpolators)
 * [Number Formats](#number-formats)
 * [Paths](#paths)
+* [Polygons](#polygons)
 * [Random Numbers](#random-numbers)
 * [Requests](#requests)
 * [Scales](#scales) ([Continuous](#continuous), [Sequential](#sequential), [Quantize](#quantize), [Ordinal](#ordinal), [Categorical](#categorical))
@@ -315,6 +316,16 @@ Serialize Canvas path commands to SVG.
 * [*path*.rect](https://github.com/d3/d3-path#path_rect) - draw a rectangle.
 * [*path*.toString](https://github.com/d3/d3-path#path_toString) - serialize to an SVG path data string.
 
+## [Polygons](https://github.com/d3/d3-polygon)
+
+Geometric operations for two-dimensional polygons.
+
+* [d3.polygonArea](https://github.com/d3/d3-polygon#polygonArea) - compute the area of the given polygon.
+* [d3.polygonCentroid](https://github.com/d3/d3-polygon#polygonCentroid) - compute the centroid of the given polygon.
+* [d3.polygonHull](https://github.com/d3/d3-polygon#polygonHull) - compute the convex hull of the given points.
+* [d3.polygonContains](https://github.com/d3/d3-polygon#polygonContains) - test whether a point is inside a polygon.
+* [d3.polygonLength](https://github.com/d3/d3-polygon#polygonLength) - compute the length of the given polygon’s perimeter.
+
 ## [Random Numbers](https://github.com/d3/d3-random)
 
 Generate random numbers from various distributions.

index.js

@@ -83,6 +83,14 @@ export {
   easeElasticInOut
 } from "d3-ease";
 
+export {
+  polygonArea,
+  polygonCentroid,
+  polygonHull,
+  polygonContains,
+  polygonLength
+} from "d3-polygon";
+
 export {
   path
 } from "d3-path";

package.json

@@ -45,6 +45,7 @@
     "d3-format": "0.5.0",
     "d3-interpolate": "0.4.0",
     "d3-path": "0.1.3",
+    "d3-polygon": "0.2.0",
     "d3-random": "0.2.0",
     "d3-request": "0.3.0",
     "d3-scale": "0.5.0",