D3

d3-polygon ​

此模块提供了一些二维多边形的基本几何运算。每个多边形都表示为一个由双元素数组 [[x0, y0], [x1, y1], …] 组成的数组，可以是闭合的（其中第一个点和最后一个点相同），也可以是开放的（其中第一个点和最后一个点不同）。Typically polygons are in counterclockwise order, assuming a coordinate system where the origin is in the top-left corner.

¥This module provides a few basic geometric operations for two-dimensional polygons. Each polygon is represented as an array of two-element arrays [​[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.

polygonArea(polygon) ​

js
d3.polygonArea([[1, 1], [1.5, 0], [2, 1]]) // -0.5

源代码 · 返回指定多边形的有符号面积。如果多边形的顶点按逆时针方向排列（假设坐标系的原点位于左上角），则返回的面积为正数；否则为负数或零。

¥Source · 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 is in the top-left corner), the returned area is positive; otherwise it is negative, or zero.

polygonCentroid(polygon) ​

js
d3.polygonCentroid([[1, 1], [1.5, 0], [2, 1]]) // [1.5, 0.6666666666666666]

源代码 · 返回指定多边形的 centroid。

¥Source · Returns the centroid of the specified polygon.

polygonHull(points) ​

js
d3.polygonHull(points) // [[3.0872864263338777, -1.300100095019402], [1.6559368816733773, -2.5092525689499605], …]

源代码 · 使用 Andrew 的单调链算法 返回指定点的 凸包。返回的外壳表示为一个数组，其中包含按逆时针顺序排列的输入点子集。如果 points 的元素少于三个，则返回 null。

¥Source · 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.

polygonContains(polygon, point) ​

js
d3.polygonContains([[1, 1], [1.5, 0], [2, 1]], [1.5, 0.667]) // true

源代码 · 当且仅当指定的点位于指定的多边形内，则返回 true。

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

polygonLength(polygon) ​

js
d3.polygonLength([[1, 1], [1.5, 0], [2, 1]]) // 3.23606797749979

源代码 · 返回指定多边形的周长。

¥Source · Returns the length of the perimeter of the specified polygon.