Math.ts

import type { Vector } from "@shopify/react-native-skia";
import { dist, vec } from "@shopify/react-native-skia";

export const getPointAtLength = (length: number, from: Vector, to: Vector) => {
  const angle = Math.atan2(to.y - from.y, to.x - from.x);
  const x = from.x + length * Math.cos(angle);
  const y = from.y + length * Math.sin(angle);
  return vec(x, y);
};

export const scale = (v: Vector, s: number) => vec(v.x * s, v.y * s);

export const length = (v: Vector) => Math.hypot(v.x, v.y);

export const normalize = (v: Vector) => scale(v, 1 / length(v));

export const dot = (a: Vector, b: Vector) => a.x * b.x + a.y * b.y;

export const distToLine = (p: Vector, v: Vector, w: Vector) => {
  const l2 = dist(v, w);
  if (l2 === 0) {
    return dist(p, v);
  }
  let t = ((p.x - v.x) * (w.x - v.x) + (p.y - v.y) * (w.y - v.y)) / l2;
  t = Math.max(0, Math.min(1, t));
  return dist(p, { x: v.x + t * (w.x - v.x), y: v.y + t * (w.y - v.y) });
};