Не получается воспроизвести пример из книги по графике на С - C (СИ)

main()
{
    float xA, yA, xB, yB, xC, yC, xD, yD, xxA, yyA, xxB, yyB, xxC, yyC, xxD, yyD, p, q;
    int i;
    p = 0.95;
    q = 1.0 - p;
    xA = 2.0;
    xB = 8.0;
    xC = 8.0;
    xD = 2.0;
    yA = 0.5;
    yB = 0.5;
    yC = 6.5;
    yD = 6.5;
    initgr();
    for (i = 0; i < 50; i++)
    {
        move(xA, yA);
        draw(xB, yB);
        draw(xC, yC);
        draw(xD, yD);
        draw(xA, yA);
        xxA = p * xA + q * xB;
        yyA = p * yA + q * yB;
        xxB = p * xB + q * xC;
        yyB = p * yB + q * yC;
        xxC = p * xC + q * xD;
        yyC = p * yC + q * yD;
        xxD = p * xD + q * xA;
        yyD = p * yD + q * yA;
        xA = xxA;
        xB = xxB;
        xC == xxC;
        xD = xxD;
        yA = yyA;
        yB = yyB;
        yC = yyC;
        yD = yyD;
    }
    endgr();
}