Splines to Gcode from dxf file

void SPLINE_FEED(double x1, double y1, double x2, double y2, double x3, double y3) {     double x0 = 0;     double y0 = 0;     pvec_v.push_back({0,0,0});     for(int i=1; i<=100; i++) {      double t = i / 100.;         double t3 = t*t*t;         double t2 = 3*t*t*(1-t);         double t1 = 3*t*(1-t)*(1-t);         double t0 = (1-t)*(1-t)*(1-t);         double x = x0*t0 + x1*t1 + x2*t2 + x3*t3;         double y = y0*t0 + y1*t1 + y2*t2 + y3*t3;         double z = 0;         pvec_v.push_back({x,y,z});     } } void cubic_spline(){     std::vector<std::vector<double>> C; //2d array     C.push_back({0,0});     C.push_back({100,50});     C.push_back({200,-50});     C.push_back({300,50});     double S[C.size()-1][2][4];     double w, b[C.size()], d[C.size()], x[C.size()];     int i, dim;     int n = C.size()-1; // number of splines     for(dim=0; dim<2; dim++)     {         // define d[]:         d[0]=3.0*(C[1][dim]-C[0][dim]);         for(i=1; i<n; i++)             d[i]=3.0*(C[i+1][dim]-C[i-1][dim]);         d[n]=3.0*(C[n][dim]-C[n-1][dim]);         // forward sweep: (simplified tridiagonal solution: all a[i]=1 and all c[i]=1)         b[0]=2.0;         for(i=1; i<C.size(); i++)         {             w = 1.0/b[i-1];             b[i] = 4.0 - w;             d[i] -= (w*d[i-1]);         }         // calculate solution vector x[i] = D[i]:         // (Wikipedia x[] = Wolfram D[])         x[n]=d[n]/b[n];         for(i=n-1; i>=0; i--)             x[i]=(d[i]-x[i+1])/b[i];         // calculate spline S[i][dim] a, b, c and d:         for(i=0; i<n; i++)         {             S[i][dim][0]=C[i][dim];             S[i][dim][1]=x[i];             S[i][dim][2]=3.0*(C[i+1][dim]-C[i][dim]) - 2.0*x[i] - x[i+1];             S[i][dim][3]=2.0*(C[i][dim]-C[i+1][dim]) + x[i] + x[i+1];         }     }     for(int p=0; p<C.size()-1; p++)  //spline points     {         for(double t=0; t<1; t+=0.01)  //time 0-1 for each spline         {             double px = ((S[p][0][3]*t+S[p][0][2])*t+S[p][0][1])*t+S[p][0][0];             double py = ((S[p][1][3]*t+S[p][1][2])*t+S[p][1][1])*t+S[p][1][0];             //std::cout<< "x:" << px << " y:" << py << std::endl;             pvec_a.push_back({px,py,0});         }     } } void MainWindow::on_pushButton_pressed() {     //!     Handle(AIS_Shape) ashape=draw_primitives().draw_3d_origin({0,0,0},5);     OpencascadeWidget->show_shape(ashape);     ashape=draw_primitives().draw_3d_origin({100,50,0},5);     OpencascadeWidget->show_shape(ashape);     ashape=draw_primitives().draw_3d_origin({200,-50,0},5);     OpencascadeWidget->show_shape(ashape);      ashape=draw_primitives().draw_3d_origin({300,50,0},5);     OpencascadeWidget->show_shape(ashape);     OpencascadeWidget->Redraw();     SPLINE_FEED(100,50,200,-50,300,50);     cubic_spline(); //black     gp_Pnt p;     std::vector<gp_Pnt> pvec;     p.SetXYZ({0,0,0});     pvec.push_back(p);     p.SetXYZ({100,50,0});     pvec.push_back(p);     p.SetXYZ({200,-50,0});     pvec.push_back(p);     p.SetXYZ({300,50,0});     pvec.push_back(p);     ashape=draw_primitives().draw_3d_spline(pvec,10);     OpencascadeWidget->show_shape(ashape);     ashape=draw_primitives().colorize(ashape,Quantity_NOC_GREEN,0); //green     OpencascadeWidget->Redraw();     draw_result(); }