TGeoVolume *bigTorus = 0;
TGeoVolume *smallTorus = 0;

void create_geometry()
{
   TCanvas *c1 = new TCanvas("c1");
   new TGeoManager("geo", "geo");

   TGeoMaterial *mat = new TGeoMaterial("Al", 26.98,13,2.7);
   TGeoMedium   *med = new TGeoMedium("MED",1,mat);
   TGeoVolume   *top = gGeoManager->MakeBox("TOP",med,100,100,100);

   gGeoManager->SetTopVolume(top);

   // define shape components with names
   bigTorus = gGeoManager->MakeTorus("torus1", med, 45., 5., 10.);
   bigTorus->SetLineColor(kRed);
   smallTorus = gGeoManager->MakeTorus("torus2", med, 25., 4., 8.);
   smallTorus->SetLineColor(kCyan);

   top->AddNode(bigTorus, 1);
   top->AddNode(smallTorus, 1);

   gGeoManager->CloseGeometry();
   gGeoManager->SetNsegments(40);
   top->Draw("ogl");
}

TTimer timer(30);

void kill_timer(const char *message)
{
   std::cout<<"Animation was stopped: "<<message<<std::endl;
   timer.TurnOff();
}

//CINT doesn't want to do them local statics in animate_geometry:
// "Error: No memory for static rotationCenter"
const TGLVertex3 rotationCenter(0., 0., 0.);
const TGLVector3 rotationAxis(0., 1., 0.);
const Double_t   angle = TMath::TwoPi() / 120.;

void animate_geometry()
{
   //Workaround to check, if canvas "c1" was closed.
   if (!gROOT->GetListOfCanvases()->FindObject("c1"))
      return kill_timer("canvas was closed.");

   //Workaround - CINT's dynamic_cast does not work.
   //TGLViewer *viewer = dynamic_cast<TGLViewer *>(gPad->GetViewer3D());
   TGLViewer * viewer = 0;
   if (gPad->GetViewer3D()->InheritsFrom("TGLViewer"))
      viewer = static_cast<TGLViewer *>(gPad->GetViewer3D());
   else
      return kill_timer("no gl-viwer.");

   if (viewer->GetHackedShapesNumber() != 2)
      return kill_timer("unexpected number of shapes in gl-scene.");

   TGLPhysicalShape   *bigTorusGL = 0;
   TGLPhysicalShape   *smallTorusGL = 0;
   TGLPhysicalShape  **shapes = viewer->GetHackedShapes();

   TGeoVolume *testVolume = static_cast<TGeoVolume *>(shapes[0]->GetLogical().GetExternal());
   testVolume == bigTorus ? bigTorusGL = shapes[0] : testVolume == smallTorus ? smallTorusGL = shapes[0] : 0;
   testVolume = static_cast<TGeoVolume *>(shapes[1]->GetLogical().GetExternal());
   testVolume == bigTorus ? bigTorusGL = shapes[1] : testVolume == smallTorus ? smallTorusGL = shapes[1] : 0;

   if (!smallTorusGL || !bigTorusGL)
      return kill_timer("unknown shapes in gl scene.");

   smallTorusGL->Rotate(rotationCenter, rotationAxis, angle);
   bigTorusGL->Rotate(rotationCenter, rotationAxis, -angle);
   viewer->RequestDraw(TGLDrawFlags::kLODMed);//kLODHigh
}

void animation()
{
   gSystem->Load("libGeom");
   create_geometry();
   timer.SetCommand("animate_geometry()");
   timer.TurnOn();
}