Function normalize

docs/tests/v2/es6/js/sanddance.js:16335–16348

* Normalize a vec2 * * @param {vec2} out the receiving vector * @param {vec2} a vector to normalize * @returns {vec2} out

(out, a)

function normalize(out, a) {
  var x = a[0],
      y = a[1];
  var len = x * x + y * y;

  if (len > 0) {
    //TODO: evaluate use of glm_invsqrt here?
    len = 1 / Math.sqrt(len);
  }

  out[0] = a[0] * len;
  out[1] = a[1] * len;
  return out;
}
/**
 * Calculates the dot product of two vec2's
 *