invert method

void invert()

Invert in place (works for non-unit quaternions too).

Implementation

void invert() {
  final n = lengthSquared;
  if (n < 1e-24) {
    setIdentity();
    return;
  }
  final inv = 1.0 / n;
  x = -x * inv;
  y = -y * inv;
  z = -z * inv;
  w = w * inv;
}