void view(const char *what = "GFOIL", Int_t vislevel = 0, const char *opt = "ogl", Bool_t topVisible=kFALSE)
{
	// load libraries and open the TGeo manager
	gSystem->Load("libGeom");
	if (gGeoManager) delete gGeoManager;
	gGeoManager = new TGeoManager("ITS", "Simple ITS geometry");
	
	// initialize the ITS materials
	Int_t medOffset = 0, matOffset = 0;
	AliITSv11GeometrySPD *spd = new AliITSv11GeometrySPD;
	spd->CreateSPDCentralMaterials(medOffset, matOffset);
	
	// create a dummy volume
	TGeoVolume *top = 0;
	
	// define some dummy size variables
	Double_t length, width, thickness;
	
	// check the option
	TString str(what);
	str.ToUpper();
	if (str.Contains("LADDER")) {
		top = spd->CreateLadder(1, length, width, thickness);
		cout << endl << endl << "--- SIZES ---" << endl << endl;
		cout << "LENGTH    (mm) = " << length * 10.0 << endl;
		cout << "WIDTH     (mm) = " << width * 10.0 << endl;
		cout << "THICKNESS (mm) = " << thickness * 10.0 << endl << endl;
	}
	else if (str.Contains("GFOILK")) {
		top = spd->CreateGroundingFoilSingle(kTRUE, length, width, thickness);
		cout << endl << endl << "--- SIZES ---" << endl << endl;
		cout << "LENGTH    (mm) = " << length * 10.0 << endl;
		cout << "WIDTH     (mm) = " << width * 10.0 << endl;
		cout << "THICKNESS (mm) = " << thickness * 10.0 << endl << endl;
	}
	else if (str.Contains("GFOILA")) {
		top = spd->CreateGroundingFoilSingle(kTRUE, length, width, thickness);
		cout << endl << endl << "--- SIZES ---" << endl << endl;
		cout << "LENGTH    (mm) = " << length * 10.0 << endl;
		cout << "WIDTH     (mm) = " << width * 10.0 << endl;
		cout << "THICKNESS (mm) = " << thickness * 10.0 << endl << endl;
	}
	else if (str.Contains("GFOIL")) {
		top = spd->CreateGroundingFoil(thickness);
		cout << endl << endl << "--- SIZES ---" << endl << endl;
		cout << "THICKNESS (mm) = " << thickness * 10.0 << endl << endl;
	}
	else if (str.Contains("MCMBASE")) {
		top = spd->CreateMCMBase();
	}
	else if (str.Contains("MCMCAP")) {
		top = spd->CreateMCMCoverBorder();
	}
	else if (str.Contains("STAVEB")) {
		Double_t a, b, c;
		top = spd->CreateStaveBase(1, a, b, c);
	}
	else if (str.Contains("STAVE")) {
		Double_t a;
		top = spd->CreateStave(1, a);
	}
	else if (str.Contains("BUS")) {
		Double_t a;
		top = spd->CreatePixelBusAndExtensions(kTRUE);
	}
	else if (str.Contains("SECTOR")) {
		Double_t a, b;
		TGeoMedium *vacuum = gGeoManager->GetMedium("VACUUM");
		TGeoVolume *top = gGeoManager->MakeBox("TOP", vacuum, 20., 20., 50.);
		//top = spd->SectorPlusStaves(top, a, b);
		top = spd->CarbonFiberSector(top, a, b);
	}
	else if (str.Contains("SPD")) {
		Double_t a, b;
		TGeoMedium *vacuum = gGeoManager->GetMedium("VACUUM");
		TGeoVolume *top = gGeoManager->MakeBox("TOP", vacuum, 50., 50., 50.);
		top = spd->SPDSector(top);
	}
	else {
		cerr << "Invalid option" << endl;
		return;
	}
	
	// set top properties
	top->SetLineColor(kCyan);
	top->SetTransparency(20);
	gGeoManager->SetTopVolume(top);
	gGeoManager->SetTopVisible(topVisible);
	
	// close the geometry project environment
	gGeoManager->CloseGeometry();
	gGeoManager->CheckOverlaps(0.00001);
	gGeoManager->PrintOverlaps();
	
	// draw
	gGeoManager->SetVisLevel(vislevel);
	top->Draw(opt);
}