void viewControl::cam_RotateU(const float& cita)
{
    mat4 rot = rotateN(_u,cita/180.0f*M_PI);
    _n = normalize(rot*_n);
    _v = normalize(rot*_v);
    _u = normalize(rot*_u);
    _cam_view = LookAt(_cam_pos,_cam_pos+_n,_v);   
}
float2 View::toScreen(float2 p) const
{
    p -= position;
    p = rotateN(p, rot);
    p /= getScale();
    p += 0.5f * sizePoints;
    return p;
}