how to draw a star ??

[timob256]

I'm trying to draw a star BUT it doesn't work out for me.

I have a formula. But I still have no idea how to embed it in my code.

all I could do was a circle or 3 loops.

struct strKryg
    {
        strKryg()
        {
            R = 0.0; kol_toch = 0;
            tocka_1 = 0; tocka_2 = 0;
            X = 0.0; Y = 0.0;
            integerVector.clear();
        }
        float R;                        // радиус
        int kol_toch;                   // колич точек которые будут формировать круг
        int tocka_1;                    // точка выреза начало
        int tocka_2;                    // точка выреза конец
        float X; float Y;               // расположение икса и игрика
    
        QVector<float> integerVector;   // вектор куда кладём точки (Х и У)
    };
....
         _mytKrg.integerVector.append(_mytKrg.X + (_mytKrg.R * cos(grad_kol_toch*M_PI*3/180.0)+_mytKrg.R * cos(grad_kol_toch*M_PI*5/5*180.0)));
        _mytKrg.integerVector.append(_mytKrg.Y + (_mytKrg.R * sin(grad_kol_toch*M_PI/180.0)));

....

            painter.drawPoint(QPointF(_mytKrg.integerVector[_mytKrg.tocka_1],_mytKrg.integerVector[_mytKrg.tocka_2]));

is there any book about how to draw with formulas (preferably on qt) ??