d4_polygon library

This package provides a few basic geometric operations for two-dimensional polygons.

Each polygon is represented as an list of two-element list [​[x0, y0], [x1, y1], …], 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 is in the top-left corner.

Functions

polygonArea(List<List<num>> polygon) → num

Returns the signed area of the specified polygon.

polygonCentroid(List<List<num>> polygon) → List<num>

Returns the centroid of the specified polygon.

polygonContains(List<List<num>> polygon, List<num> point) → bool

Returns true if and only if the specified point is inside the specified polygon.

polygonHull(List<List<num>> points) → List<List<num>>?

Returns the convex hull of the specified points using Andrew’s monotone chain algorithm.

polygonLength(List<List<num>> polygon) → num

Returns the length of the perimeter of the specified polygon.