angleTo method
Returns the angle between this vector and vector v in radians.
Implementation
double angleTo(Vector3 v) {
var denominator = math.sqrt(lengthSq() * v.lengthSq());
if (denominator == 0) return math.pi / 2;
var theta = dot(v) / denominator;
// clamp, to handle numerical problems
return math.acos(MathUtils.clamp(theta, -1, 1));
}