bresenham

void Besenham(int x1, int y1, int x2, int y2) {
        boolean zapamataj = false;
        boolean bolaVymena1 = false;
        boolean bolaVymena2 = false;

        if (Math.abs(x2 - x1) < Math.abs(y2 - y1)) {
            int pom;
            pom = x1; x1 = y1; y1 = pom;
            pom = x2; x2 = y2; y2 = pom;
            zapamataj = true;
            glColor3d(255, 0, 0);
            bolaVymena1 = true;
        }

        if (x2 < x1) {
            int pom;
            pom = x1; x1 = x2; x2 = pom;
            pom = y1; y1 = y2; y2 = pom;
            glColor3d(0, 0, 255);
            bolaVymena2 = true;
        }

        if (bolaVymena1 && bolaVymena2) {
            glColor3d(0, 255, 0);
        }

        if (!bolaVymena1 && !bolaVymena2) {
            glColor3d(255, 255, 255);
        }

        int krok = y2 < y1 ? -1 : 1;
        int dx = x2 - x1;
        int dy = Math.abs(y2 - y1);
        int y = y1;
        int k1 = 2 * dy;
        int k2 = 2 * dy - 2 * dx;
        int d = 2 * dy - dx;

        for (int x = x1; x <= x2; x++) {
            if (zapamataj) {
                Bod(y, x);
            } else {
                Bod(x, y);
            }
            if (d < 0) {
                d = d + k1;
            } else {
                d = d + k2;
                y = y + krok;
            }
        }
    }