Function relation

Tracks the relation between two points.

1. Call Points.relation with the initial reference point
2. You get back a function
3. Call the function with a new point to compute relational information.

It computes angle, average, centroid, distance and speed.

import { Points } from "https://unpkg.com/ixfx/dist/geometry.js";

// Reference point: 50,50
const t = Points.relation({x:50,y:50}); // t is a function

// Invoke the returned function with a point
const relation = t({ x:0, y:0 }); // Juicy relational data
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Or with destructuring:

const { angle, distanceFromStart, distanceFromLast, average, centroid, speed } = t({ x:0,y:0 });
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x & y coordinates can also be used as parameters:

const t = Points.relation(50, 50);
const result = t(0, 0);
// result.speed, result.angle ...
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Note that intermediate values are not stored. It keeps the initial and most-recent point. If you want to compute something over a set of prior points, you may want to use Trackers.points