@thi.ng/vectors/refract.js

Optimized 2d/3d/4d and arbitrary length vector operations, support for memory mapping/layouts

import { dot } from "./dot.js";
import { maddN } from "./maddn.js";
import { mulN } from "./muln.js";
import { zero } from "./setn.js";
const refract = (out, a, n, eta) => {
  !out && (out = a);
  const d = dot(a, n);
  const k = 1 - eta * eta * (1 - d * d);
  return k < 0 ? zero(out) : maddN(out, n, -(eta * d + Math.sqrt(k)), mulN(out, a, eta));
};
export {
  refract
};