compare-slope

Ranks the slope of a pair of vectors through the origin in clockwise order. This is more robust than comparing their arc tangents using atan2.

Use

First install using npm:

npm install compare-slope

Then use as follows:

var compareSlope = require("compare-slope")

console.log(compareSlope([0, 1], [1, 2]))

require("compare-slope")(a, b)

Checks whether a comes before b in a counter-clockwise ordering.

• a and b are both represented by arrays of at least length 2

Returns:

• > 0 if b is clockwise from a
• < 0 if a is clockwise from b
• 0 if a and b are collinear

Note: Somewhat arbitrarily, the degenerate point at the origin is ranked before all other points.

Credits

(c) 2013 Mikola Lysenko. MIT License