TCanvas* c1 = new TCanvas(); TGraph* graph = new TGraph(5, x, y); graph->SetFillColor(kRed); graph->Draw("AB");
TCanvas* c1 = new TCanvas(); TGraph* graph1 = new TGraph(5, x, y); graph1->SetFillColor(kRed); TGraph* graph2 = new TGraph(5, x, z); graph2->SetFillColor(kBlue); THStack* stack = new THStack("stack", "Stacked Graphs"); stack->Add(graph1); stack->Add(graph2); stack->Draw("AB");In this example, we create two TGraph objects with 5 points each and set their filling colors to red and blue, respectively. We then create a THStack object and add the two graphs to it. We then draw the THStack using Draw() with an "AB" option. Based on the code examples provided and the reference to ROOT data analysis framework, it can be determined that the package/library being used for SetFillColor() is ROOT.