void gliso()
{
   const Int_t nBin = 70;
   const Double_t l = -40., r = 40.;
   Double_t w = (r-l)/nBin;
   TH3F *volume = new TH3F("V","V", nBin, l, r, nBin, l, r, nBin, l, r);
   TCanvas *canvas = new TCanvas("glC","glC",600,600);
                                                                                
   //Define and set user's palette,
   const Int_t paletteSize = 5;
   Float_t rgb[paletteSize * 3] =
      {0.9f, 0.60f, 0.f,
       0.f,  1.f,   1.f,
       1.f,  0.f,   0.f,
       0.f,  1.f,   0.f,
       1.f,  1.f,   0.f};
                                                                                
   Int_t palette[paletteSize] = {0};
                                                                                
   for (Int_t i = 0; i < paletteSize; ++i)
      palette[i] = TColor::GetColor(rgb[i * 3], rgb[i * 3 + 1], rgb[i * 3 + 2]);                                                                                
   gStyle->SetPalette(paletteSize, palette);
                                                                                
   Float_t x,y,z;
   for (x = l-w/2; x < r; x += w) {
      for (y = l-w/2; y < r; y += w) {
         for (z = l-w/2; z < r; z += w) {
            if ( x*x + y*y + z*z < 500) volume->Fill(x,y,z,50);
            if ( x*x + y*y + z*z < 300) volume->Fill(x,y,z,40);
            if ( x*x + y*y + z*z < 200) volume->Fill(x,y,z,30);
            if ( x*x + y*y + z*z < 80)  volume->Fill(x,y,z,20);
            if ( x*x + y*y + z*z < 30)  volume->Fill(x,y,z,10);
         }
      }
   }
                                                                                
   volume->SetContour(5);
   volume->Draw("gliso");
}