2D immutable vector representation utilities

Vec2.js

import { toRadians, toDegrees } from './math.js';

export const Vec2 = {
  of (x, y) {
    return { x, y };
  },

  length (v) {
    return Math.sqrt(v.x ** 2 + v.y ** 2);
  },

  angle (v) {
    return toDegrees(Math.atan2(v.y, v.x));
  },

  equals (v1, v2) {
    return v1.x === v2.x && v1.y === v2.y;
  },

  distance (v1, v2) {
    return Vec2.length(Vec2.subtract(v1, v2))
  },

  add (v1, v2) {
    return Vec2.of(v1.x + v2.x, v1.y + v2.y);
  },

  subtract (v1, v2) {
    return Vec2.of(v1.x - v2.x, v1.y - v2.y);
  },

  cross (v1, v2) {
    return Vec2.of(v1.x * v2.x, v1.y * v2.y);
  },

  multiplyScalar (v, scalar = 1) {
    return Vec2.of(v.x * scalar, v.y * scalar);
  },

  normalize (v) {
    return Vec2.multiplyScalar(v, 1 / Vec2.length(v));
  },

  rotate (v, radians = 0, c = Vec2.of(0, 0)) {
    return Vec2.of(
      c.x + (v.x - c.x) * Math.cos(radians) - (v.y - c.y) * Math.sin(radians),
      c.y + (v.x - c.x) * Math.sin(radians) + (v.y - c.y) * Math.cos(radians)
    );
  },

  reverse (v) {
    return Vec2.rotate(v, toRadians(180));
  },
};