graphShade.C

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/// \file
/// \ingroup tutorial_graphs
/// \notebook
/// Show how to shade an area between two graphs
///
/// \macro_image
/// \macro_code
///
/// \author Rene Brun
 
void graphShade()
{
   TCanvas *c1 = new TCanvas("c1", "A Simple Graph Example", 200, 10, 700, 500);
 
   c1->SetGrid();
   c1->DrawFrame(0, 0, 2.2, 12);
 
   const Int_t n = 20;
   Double_t x[n], y[n], ymin[n], ymax[n];
   Int_t i;
   for (i = 0; i < n; i++) {
      x[i] = 0.1 + i * 0.1;
      ymax[i] = 10 * sin(x[i] + 0.2);
      ymin[i] = 8 * sin(x[i] + 0.1);
      y[i] = 9 * sin(x[i] + 0.15);
   }
   TGraph *grmin = new TGraph(n, x, ymin);
   TGraph *grmax = new TGraph(n, x, ymax);
   TGraph *gr = new TGraph(n, x, y);
   TGraph *grshade = new TGraph(2 * n);
   for (i = 0; i < n; i++) {
      grshade->SetPoint(i, x[i], ymax[i]);
      grshade->SetPoint(n + i, x[n - i - 1], ymin[n - i - 1]);
   }
   grshade->SetFillStyle(3013);
   grshade->SetFillColor(16);
   grshade->Draw("f");
   grmin->Draw("l");
   grmax->Draw("l");
   gr->SetLineWidth(4);
   gr->SetMarkerColor(4);
   gr->SetMarkerStyle(21);
   gr->Draw("CP");
}