Geant4 User's Guide for Application Developers - Geant4 - CERN

Visualization{G4VVisManager* pVVisManager = G4VVisManager::GetConcreteInstance();if (pVVisManager) {//----- Get the Stepping Managerconst G4SteppingManager* pSM = GetSteppingManager();//----- Define a line segmentG4Polyline polyline;G4double charge = pSM->GetTrack()->GetDefinition()->GetPDGCharge();G4Colour colour;if (charge < 0.) colour = G4Colour(1., 0., 0.);else if (charge < 0.) colour = G4Colour(0., 0., 1.);else colour = G4Colour(0., 1., 0.);G4VisAttributes attribs(colour);polyline.SetVisAttributes(attribs);polyline.push_back(pSM->GetStep()->GetPreStepPoint()->GetPosition());polyline.push_back(pSM->GetStep()->GetPostStepPoint()->GetPosition());//----- Call a drawing method for G4PolylinepVVisManager -> Draw(polyline);}}//----- end of C++ source codeNext, in order that the above C++ source code works, you have to pass the information of the MySteppingActionto the Run Manager in the main() function://----- C++ source code: Passing what to do at each step to the Run Managerint main(){...// Run ManagerG4RunManager * runManager = new G4RunManager;}// User initialization classes...runManager->SetUserAction(new MySteppingAction);...//----- end of C++ source codeThus you can visualize tracking steps with various visualization attributes, e.g., color, at each step, automatically.As well as tracking steps, you can visualize any kind 3D object made of line segments, using class G4Polylineand its drawing method, defined in class G4VVisManager. See, for example, the implementation of the /vis/scene/add/axes command.8.5.10. Visualization User ActionYou can implement the Draw method of G4VUserVisAction, e.g., the class definition could be:class StandaloneVisAction: public G4VUserVisAction {void Draw();};and the implementation:void StandaloneVisAction::Draw() {250