CalcAngle

void CalculateAngle(const Vector &source, const Vector &destination, QAngle& angles)
{
        Vector delta = source - destination;
        angles.pitch = static_cast< float >(asin(delta.z / delta.Length()) * M_RADPI);
        angles.yaw = static_cast< float >(atan(delta.y / delta.x) * M_RADPI);
        angles.roll = 0.0f;

        if (delta.x >= 0.0f)
            angles.yaw += 180.0f;
    }