enum directions{
    UP,
    DOWN,
    RIGHT,
    LEFT,
    IN,
    OUT,
    FW,
    RW
};

class Snake
{
private:
    enum directions head_dir;
    enum directions head_dir_ask; //if I comment this... the program work fine..
    (... other stuff...)
};

MainProject::MainProject(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainProject)
{
    ui->setupUi(this);
    startTimer(1000);
    glwidget = new MyGLBox(ui->centralWidget);
    ui->GLlayout->addWidget(glwidget); // <line where the complier retruns the EXC_BAD_ACCESS
}

MyGLBox::MyGLBox(QWidget *parent):QGLWidget(parent){
   XRot = YRot = ZRot = 0;
    theta1 = theta2 = phi = 0;
}