geant events for multiple scattering

src/Vtk/HEP/Geant/testing/vtkGeantEventTest.cpp

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+/*//////////////////////////////////////////////////////////////////////////////
+// CMT Cosmic Muon Tomography project //////////////////////////////////////////
+////////////////////////////////////////////////////////////////////////////////
+
+  Copyright (c) 2014, Universita' degli Studi di Padova, INFN sez. di Padova
+  All rights reserved
+
+  Authors: Andrea Rigoni Garola < andrea.rigoni@pd.infn.it >
+
+//////////////////////////////////////////////////////////////////////////////*/
+
+#include "Geant/Solid.h"
+#include "HEP/Geant/GeantEvent.h"
+#include "HEP/Geant/Scene.h"
+#include "HEP/Geant/EmitterPrimary.hh"
+#include "Math/ContainerBox.h"
+#include "Math/Dense.h"
+#include "Vtk/uLibVtkViewer.h"
+#include "Vtk/HEP/Geant/vtkGeantEvent.h"
+#include "Vtk/vtkContainerBox.h"
+
+#include <vtkSmartPointer.h>
+#include <vtkCallbackCommand.h>
+#include <vtkRenderWindowInteractor.h>
+#include <vtkProperty.h>
+#include <vtkRenderer.h>
+#include <vtkRenderWindow.h>
+
+#include <Geant4/Randomize.hh>
+#include <Geant4/G4ParticleGun.hh>
+#include <Geant4/G4SystemOfUnits.hh>
+
+#include <iostream>
+
+using namespace uLib;
+
+// Custom emitter to fire random muons towards the cube
+class RandomEmitter : public Geant::EmitterPrimary {
+public:
+    virtual void GeneratePrimaries(G4Event* anEvent) override {
+        // Start from a random point in a square at z = 5m
+        // Note: unit in Geant4 is mm by default if not specified, 
+        // but here we use the constants from G4SystemOfUnits.h
+        double x = (G4UniformRand() - 0.5) * 2000; // -1m to 1m
+        double y = (G4UniformRand() - 0.5) * 2000; // -1m to 1m
+        double z = 5000.0; // 5m above origin
+        
+        fParticleGun->SetParticlePosition(G4ThreeVector(x, y, z));
+        
+        // Aim at a random point within the cube (which is at origin, size 1m)
+        double tx = (G4UniformRand() - 0.5) * 1000;
+        double ty = (G4UniformRand() - 0.5) * 1000;
+        double tz = (G4UniformRand() - 0.5) * 1000;
+        
+        G4ThreeVector dir(tx - x, ty - y, tz - z);
+        dir = dir.unit();
+        fParticleGun->SetParticleMomentumDirection(dir);
+        
+        fParticleGun->GeneratePrimaryVertex(anEvent);
+    }
+};
+
+struct AppState {
+    Geant::Scene* scene;
+    Vtk::Viewer* viewer;
+    Vector<Geant::GeantEvent> results;
+};
+
+void KeyPressCallbackFunction(vtkObject* caller, long unsigned int eventId, void* clientData, void* callData) {
+    auto* interactor = static_cast<vtkRenderWindowInteractor*>(caller);
+    auto* state = static_cast<AppState*>(clientData);
+    
+    std::string key = interactor->GetKeySym();
+    if (key == "Return") {
+        std::cout << "--> Firing random muon..." << std::endl;
+        
+        // Run one event
+        state->scene->RunSimulation(1, state->results);
+        
+        if (!state->results.empty()) {
+            // Get the last event
+            Geant::GeantEvent* lastEvent = &state->results.back();
+            std::cout << "    Collected event " << lastEvent->GetEventID() 
+                      << " with " << lastEvent->Path().size() << " steps." << std::endl;
+                      
+            // Wrap it for VTK
+            Vtk::vtkGeantEvent* vtkEvent = new Vtk::vtkGeantEvent(lastEvent);
+            state->viewer->AddPuppet(*vtkEvent);
+            
+            // Re-render
+            state->viewer->GetRenderer()->Render();
+            state->viewer->GetRenderWindow()->Render();
+        }
+    }
+}
+
+int main(int argc, char** argv) {
+    // 1. Setup Geant4 Scene
+    ContainerBox world_box(Vector3f(30000, 30000, 30000));
+    Geant::Scene scene;
+    scene.ConstructWorldBox(&world_box, "G4_AIR");
+
+    ContainerBox iron_box(Vector3f(1000, 1000, 1000));
+    Geant::BoxSolid* iron_cube = new Geant::BoxSolid("IronCube", &iron_box);
+    iron_cube->SetNistMaterial("G4_Fe");
+    iron_cube->Update();
+    scene.AddSolid(iron_cube);
+
+    RandomEmitter* emitter = new RandomEmitter();
+    scene.SetEmitter(emitter);
+    scene.Initialize();
+
+    // 2. Setup VTK Viewer
+    Vtk::Viewer viewer;
+    viewer.GetRenderer()->SetBackground(0.05, 0.05, 0.1);
+    
+    // Visualize iron cube
+    Vtk::vtkContainerBox* vtkIron = new Vtk::vtkContainerBox(&iron_box);
+    viewer.AddPuppet(*vtkIron);
+    
+    // 3. Event Handling
+    AppState state = { &scene, &viewer, {} };
+    
+    vtkSmartPointer<vtkCallbackCommand> keyCallback = vtkSmartPointer<vtkCallbackCommand>::New();
+    keyCallback->SetCallback(KeyPressCallbackFunction);
+    keyCallback->SetClientData(&state);
+    
+    viewer.GetInteractor()->AddObserver(vtkCommand::KeyPressEvent, keyCallback);
+
+    std::cout << "=================================================" << std::endl;
+    std::cout << " Geant Muon Simulation Viewer" << std::endl;
+    std::cout << " Press [ENTER] to fire a new random muon" << std::endl;
+    std::cout << " Press [q] to exit" << std::endl;
+    std::cout << "=================================================" << std::endl;
+
+    viewer.ZoomAuto();
+    viewer.Start();
+
+    return 0;
+}