This module provides a few basic geometric operations for two-dimensional polygons. Each polygon is represented as an array of two-element arrays [[x1, y1], [x2, y2], …], and may either be closed (wherein the first and last point are the same) or open (wherein they are not). Typically polygons are in counterclockwise order, assuming a coordinate system where the origin ⟨0,0⟩ is in the top-left corner.
If you use NPM,
npm install d3-polygon. Otherwise, download the latest release. You can also load directly from d3js.org, either as a standalone library or as part of D3 4.0. AMD, CommonJS, and vanilla environments are supported. In vanilla, a
d3 global is exported:
<script src="https://d3js.org/d3-polygon.v1.min.js"></script> <script> var hull = d3.polygonHull(points); </script>
Returns the signed area of the specified polygon. If the vertices of the polygon are in counterclockwise order (assuming a coordinate system where the origin ⟨0,0⟩ is in the top-left corner), the returned area is positive; otherwise it is negative, or zero.
Returns the centroid of the specified polygon.
Returns the convex hull of the specified points using Andrew’s monotone chain algorithm. The returned hull is represented as an array containing a subset of the input points arranged in counterclockwise order. Returns null if points has fewer than three elements.
Returns true if and only if the specified point is inside the specified polygon.
Returns the length of the perimeter of the specified polygon.