source: trunk/geant4/visualization/OpenGL/src/G4OpenGLQtViewer.cc @ 566

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// ********************************************************************
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// * the Geant4 Collaboration.  It is provided  under  the terms  and *
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// * technical work of the GEANT4 collaboration.                      *
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//
//
// $Id: G4OpenGLQtViewer.cc,v 1.17 2006/06/29 21:19:36 gunter Exp $
// GEANT4 tag $Name: geant4-08-01-patch-01 $
//
// 
// G4OpenGLQtViewer : Class to provide Qt specific
//                     functionality for OpenGL in GEANT4
//
// 27/06/2003 : G.Barrand : implementation (at last !).

#ifdef G4VIS_BUILD_OPENGLQT_DRIVER

#include "G4OpenGLQtViewer.hh"

#include "G4ios.hh"
#include "G4VisExtent.hh"
#include "G4LogicalVolume.hh"
#include "G4VSolid.hh"
#include "G4Point3D.hh"
#include "G4Normal3D.hh"
#include "G4Scene.hh"

#include "G4Qt.hh"
#include "G4UIManager.hh"
#include <QtGui/qboxlayout.h>
#include <QtGui/qdialog.h>
#include <QtGui/qmenu.h>
#include <QFileDialog.h>

//////////////////////////////////////////////////////////////////////////////
/**
   Implementation of virtual method of G4VViewer
*/
void G4OpenGLQtViewer::SetView (
) 
//////////////////////////////////////////////////////////////////////////////
//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!//
{
  printf("G4OpenGLQtViewer::SetView ++++++++++++++++++++\n");
  //   if(!fHDC) return;
  //   if(!fHGLRC) return;
  //   ::wglMakeCurrent(fHDC,fHGLRC);
  //  fWindow->makeCurrent();
  G4OpenGLViewer::SetView ();  
  printf("G4OpenGLQtViewer::SetView --------------------\n");
}



//////////////////////////////////////////////////////////////////////////////
/**
   Implementation of virtual method of G4VViewer
*/
void G4OpenGLQtViewer::ShowView (
) 
//////////////////////////////////////////////////////////////////////////////
//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!//
{
  printf("G4OpenGLQtViewer::ShowView  +++++++++++++++++++++\n");
  //   if(!fHDC) return;
  //  fWindow->resize(100, 300);
  glFlush ();
  printf("G4OpenGLQtViewer::ShowView -----------------------\n");

  //   // Empty the Windows message queue :
  //   MSG event;
  //   while ( ::PeekMessage(&event, NULL, 0, 0, PM_REMOVE) ) {
  //     ::TranslateMessage(&event);
  //     ::DispatchMessage (&event);
  //   }
}



//////////////////////////////////////////////////////////////////////////////
void G4OpenGLQtViewer::CreateGLQtContext (
) 
//////////////////////////////////////////////////////////////////////////////
//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!//
{
  printf("G4OpenGLQtViewer::CreateGLQtContext \n");
}


//////////////////////////////////////////////////////////////////////////////
void G4OpenGLQtViewer::CreateMainWindow (
                                         QGLWidget* glWidget
                                         ) 
//////////////////////////////////////////////////////////////////////////////
//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!//
{

  if(fWindow) return; //Done.
  printf("G4OpenGLQtViewer::CreateMainWindow glWidget\n");

  // launch Qt if not
  G4Qt* interactorManager = G4Qt::getInstance ();
  //  G4UImanager* UI = G4UImanager::GetUIpointer();

  fWindow = glWidget ;
  //  fWindow->makeCurrent();

  // create window
  if (qApp) {
    GLWindow = new QDialog();//qApp->mainWidget());
  } else {
    GLWindow = new QDialog();
  }

  QHBoxLayout *mainLayout = new QHBoxLayout;

  mainLayout->addWidget(fWindow);
  GLWindow->setLayout(mainLayout);
  GLWindow->setWindowTitle("QGl Viewer");
  GLWindow->resize(300, 300);
  GLWindow->show();
  
  WinSize_x = 400;
  WinSize_y = 400;
  if (WinSize_x < fVP.GetWindowSizeHintX ())
    WinSize_x = fVP.GetWindowSizeHintX ();
  if (WinSize_y < fVP.GetWindowSizeHintY ())
    WinSize_y = fVP.GetWindowSizeHintY ();

  if(!fWindow) return;
  printf("G4OpenGLQtViewer::CreateMainWindow glWidget END\n");

  if (!fContextMenu) 
    createPopupMenu();

}

//////////////////////////////////////////////////////////////////////////////
G4OpenGLQtViewer::G4OpenGLQtViewer (
                                    G4OpenGLSceneHandler& scene
                                    )
  :G4VViewer (scene, -1)
  ,G4OpenGLViewer (scene)
  ,fWindow(0)
  ,fContextMenu(0)
  ,fMouseAction(true)
{
  printf("G4OpenGLQtViewer::G4OpenGLQtViewer \n");
}

//////////////////////////////////////////////////////////////////////////////
G4OpenGLQtViewer::~G4OpenGLQtViewer (
) 
//////////////////////////////////////////////////////////////////////////////
//!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!//
{
  printf("G4OpenGLQtViewer::~G4OpenGLQtViewer \n");
  delete fContextMenu;    
}


/**
   Create a popup menu for the widget. This menu is activated by right-mouse click
*/
void G4OpenGLQtViewer::createPopupMenu()    {

  fContextMenu = new QMenu("All");

  QMenu *mMouseAction = fContextMenu->addMenu("&Mouse action");
  QAction *rotate = mMouseAction->addAction("&Rotate scene");
  QAction *move = mMouseAction->addAction("&Move scene");
  // INIT mMouse
  createRadioAction(rotate,move,SLOT(toggleMouseAction(bool)),1);

  //Style Menu
  QMenu *mStyle = fContextMenu->addMenu("&Style");

  QMenu *mRepresentation = mStyle->addMenu("&Representation");
  QAction *polyhedron = mRepresentation->addAction("Polyhedron");
  QAction *nurbs = mRepresentation->addAction("NURBS");
  // INIT mStyle
  G4ViewParameters::RepStyle style;
  style = fVP.GetRepStyle();
  if (style == G4ViewParameters::polyhedron) {
    createRadioAction(polyhedron,nurbs,SLOT(toggleRepresentation(bool)),1);
  } else if (style == G4ViewParameters::nurbs) {
    createRadioAction(polyhedron,nurbs,SLOT(toggleRepresentation(bool)),2);
  } else {
    mRepresentation->clear();
  }


  QMenu *mDrawing = mStyle->addMenu("&Drawing");
  fDrawingWireframe = mDrawing->addAction("Wireframe");
  fDrawingWireframe->setCheckable(true);
  fDrawingWireframe->setChecked(true);
  fDrawingLineRemoval = mDrawing->addAction("Hidden line removal");
  fDrawingLineRemoval->setCheckable(true);
  fDrawingSurfaceRemoval = mDrawing->addAction("Hidden Surface removal");
  fDrawingSurfaceRemoval->setCheckable(true);
  fDrawingLineSurfaceRemoval = mDrawing->addAction("Hidden line and surface removal");
  fDrawingLineSurfaceRemoval->setCheckable(true);
  // INIT Drawing
  G4ViewParameters::DrawingStyle d_style;
  d_style = fVP.GetDrawingStyle();
  
  fDrawingWireframe->setCheckable(true);
  fDrawingLineRemoval->setCheckable(true);
  fDrawingSurfaceRemoval->setCheckable(true);
  fDrawingLineSurfaceRemoval->setCheckable(true);

  if (d_style == G4ViewParameters::wireframe) {
    fDrawingWireframe->setChecked(true);
  } else if (d_style == G4ViewParameters::hlr) {
    fDrawingLineRemoval->setChecked(true);
  } else if (d_style == G4ViewParameters::hsr) {
    fDrawingSurfaceRemoval->setChecked(true);
  } else if (d_style == G4ViewParameters::hlhsr) {
    fDrawingLineSurfaceRemoval->setChecked(true);
  } else {
    mDrawing->clear();
  }

  QObject ::connect(fDrawingWireframe, 
                    SIGNAL(triggered(bool)),
                    this, 
                    SLOT(actionDrawingWireframe()));
  QObject ::connect(fDrawingLineRemoval, 
                    SIGNAL(triggered(bool)),
                    this, 
                    SLOT(actionDrawingLineRemoval()));
  QObject ::connect(fDrawingSurfaceRemoval, 
                    SIGNAL(triggered(bool)),
                    this, 
                    SLOT(actionDrawingSurfaceRemoval()));
  QObject ::connect(fDrawingLineSurfaceRemoval, 
                    SIGNAL(triggered(bool)),
                    this, 
                    SLOT(actionDrawingLineSurfaceRemoval()));


  QMenu *mBackground = mStyle->addMenu("&Background color");
  QAction *white = mBackground->addAction("White");
  QAction *black = mBackground->addAction("Black");
  if (background.GetRed() == 1. &&
      background.GetGreen() == 1. &&
      background.GetBlue() == 1.) {
    createRadioAction(white,black,SLOT(toggleBackground(bool)),1);
  } else {
    createRadioAction(white,black,SLOT(toggleBackground(bool)),2);
  }


  // Action Menu
  QMenu *mActions = fContextMenu->addMenu("&Actions");
  QAction *controlPanels = mActions->addAction("Control panels");
  QAction *exitG4 = mActions->addAction("Exit to G4Vis >");
  QAction *createEPS = mActions->addAction("Create .eps file");
  QObject ::connect(controlPanels, 
                    SIGNAL(triggered()),
                    this, 
                    SLOT(actionControlPanels()));
  QObject ::connect(exitG4, 
                    SIGNAL(triggered()),
                    this, 
                    SLOT(actionExitG4()));
  QObject ::connect(createEPS, 
                    SIGNAL(triggered()),
                    this,
                    SLOT(actionCreateEPS()));


  // Special Menu
  QMenu *mSpecial = fContextMenu->addMenu("S&pecial");
  QMenu *transparency = mSpecial->addMenu("Transparency");
  QAction *transparencyOn = transparency->addAction("On");
  QAction *transparencyOff = transparency->addAction("Off");
  if (transparency_enabled == false) {
    createRadioAction(transparencyOn,transparencyOff,SLOT(toggleTransparency(bool)),2);
  } else if (transparency_enabled == true) {
    createRadioAction(transparencyOn,transparencyOff,SLOT(toggleTransparency(bool)),1);
  } else {
    mSpecial->clear();
  }


  QMenu *mAntialiasing = mSpecial->addMenu("Antialiasing");
  QAction *antialiasingOn = mAntialiasing->addAction("On");
  QAction *antialiasingOff = mAntialiasing->addAction("Off");
  if (antialiasing_enabled == false) {
    createRadioAction(antialiasingOn,antialiasingOff,SLOT(toggleAntialiasing(bool)),2);
  } else if (antialiasing_enabled == true) {
    createRadioAction(antialiasingOn,antialiasingOff,SLOT(toggleAntialiasing(bool)),1);
  } else {
    mAntialiasing->clear();
  }

  QMenu *mHaloing = mSpecial->addMenu("Haloing");
  QAction *haloingOn = mHaloing->addAction("On");
  QAction *haloingOff = mHaloing->addAction("Off");
  if (haloing_enabled == false) {
    createRadioAction(haloingOn,haloingOff,SLOT(toggleHaloing(bool)),2);
  } else if (haloing_enabled == true) {
    createRadioAction(haloingOn,haloingOff,SLOT(toggleHaloing(bool)),1);
  } else {
    mHaloing->clear();
  }

  QMenu *mAux = mSpecial->addMenu("Auxiliary edges");
  QAction *auxOn = mAux->addAction("On");
  QAction *auxOff = mAux->addAction("Off");
  if (!fVP.IsAuxEdgeVisible()) {
    createRadioAction(auxOn,auxOff,SLOT(toggleAux(bool)),1);
  } else {
    createRadioAction(auxOn,auxOff,SLOT(toggleAux(bool)),2);
  }


  QMenu *mFullScreen = mSpecial->addMenu("Full screen");
  QAction *fullOn = mFullScreen->addAction("On");
  QAction *fullOff = mFullScreen->addAction("Off");
  createRadioAction(fullOn,fullOff,SLOT(toggleFullScreen(bool)),2);

}

void G4OpenGLQtViewer::manageContextMenuEvent(QContextMenuEvent *e)
{
  if (!GLWindow) return;
  
  if (!fContextMenu) 
    createPopupMenu();

  // launch menu
  if ( fContextMenu ) {
    fContextMenu->exec( e->globalPos() );
    //    delete fContextMenu;
  }
  e->accept();
}


/**
   Create a radio button menu. The two menu will be connected. When click on one,
   eatch state will be invert and callback method will be called.
   @param action1 first action to connect
   @param action2 second action to connect
   @param method callback method
   @param nCheck: 1 : first action will be set true. 2 : second action will be set true
*/
void G4OpenGLQtViewer::createRadioAction(QAction *action1,QAction *action2, const std::string& method,unsigned int nCheck) {

  action1->setCheckable(true);
  action2->setCheckable(true);

  if (nCheck ==1)
    action1->setChecked (true);
  else
    action2->setChecked (true);
   
  QObject ::connect(action1, SIGNAL(triggered(bool)),action2, SLOT(toggle()));
  QObject ::connect(action2, SIGNAL(triggered(bool)),action1, SLOT(toggle()));

  QObject ::connect(action1, SIGNAL(toggled(bool)),this, method.c_str());

}

/**
   Slot activate when drawing->wireframe menu is set 
 */
void G4OpenGLQtViewer::actionDrawingWireframe() {
  emit toggleDrawingAction(1);
}

/**
   Slot activate when drawing->line removal menu is set 
 */
void G4OpenGLQtViewer::actionDrawingLineRemoval() {
  emit toggleDrawingAction(2);
}

/**
   Slot activate when drawing->surface removal menu is set 
 */
void G4OpenGLQtViewer::actionDrawingSurfaceRemoval() {
  emit toggleDrawingAction(3);
}

/**
   Slot activate when drawing->wireframe menu is set 
 */
void G4OpenGLQtViewer::actionDrawingLineSurfaceRemoval() {
  emit toggleDrawingAction(4);
}


/**
   Slot activated when drawing menu is toggle
   Warning : When G4OpenGLStoredQtViewer::DrawView() method call,
   KernelVisitDecision () will be call and will set the fNeedKernelVisit
   to 1. See G4XXXStoredViewer::CompareForKernelVisit for explanations.
   It will cause a redraw of the view
   @param aAction : 1 wireframe, 2 line removal, 3 surface removal, 4 line & surface removal
   @see G4OpenGLStoredQtViewer::DrawView
   @see G4XXXStoredViewer::CompareForKernelVisit
 */
void G4OpenGLQtViewer::toggleDrawingAction(int aAction) {

  G4ViewParameters::DrawingStyle d_style;
  

  if (aAction ==1) {
    fDrawingWireframe->setChecked (true);
    fDrawingLineRemoval->setChecked (false);
    fDrawingSurfaceRemoval->setChecked (false);
    fDrawingLineSurfaceRemoval->setChecked (false);

    d_style = G4ViewParameters::wireframe;

  } else  if (aAction ==2) {
    fDrawingWireframe->setChecked (false);
    fDrawingLineRemoval->setChecked (true);
    fDrawingSurfaceRemoval->setChecked (false);
    fDrawingLineSurfaceRemoval->setChecked (false);

    d_style = G4ViewParameters::hlr;

  } else  if (aAction ==3) {
    fDrawingWireframe->setChecked (false);
    fDrawingLineRemoval->setChecked (false);
    fDrawingSurfaceRemoval->setChecked (true);
    fDrawingLineSurfaceRemoval->setChecked (false);

    d_style = G4ViewParameters::hsr;

  } else  if (aAction ==4) {
    fDrawingWireframe->setChecked (false);
    fDrawingLineRemoval->setChecked (false);
    fDrawingSurfaceRemoval->setChecked (false);
    fDrawingLineSurfaceRemoval->setChecked (true);

    d_style = G4ViewParameters::hlhsr;
  }
  fVP.SetDrawingStyle(d_style);

  updateQWidget();
  printf("G4OpenGLQtViewer::toggleDrawingAction\n");
}


/**
   SLOT Activate by a click on the representation menu
   Warning : When G4OpenGLStoredQtViewer::DrawView() method call,
   KernelVisitDecision () will be call and will set the fNeedKernelVisit
   to 1. See G4XXXStoredViewer::CompareForKernelVisit for explanations.
   It will cause a redraw of the view
   @param check : 1 polyhedron, 0 nurbs
   @see G4OpenGLStoredQtViewer::DrawView
   @see G4XXXStoredViewer::CompareForKernelVisit
*/
void G4OpenGLQtViewer::toggleRepresentation(bool check) {

  G4ViewParameters::RepStyle style;
  if (check == 1) {
    style = G4ViewParameters::polyhedron;
  } else {
    style = G4ViewParameters::nurbs;
  }
  fVP.SetRepStyle (style);

  printf("G4OpenGLQtViewer::toggleRepresentation 3%d\n",check);
  updateQWidget();
  printf("G4OpenGLQtViewer::toggleRepresentation 4%d\n",check);
}

/**
   SLOT Activate by a click on the background menu
@param check : 1 white, 0 black
*/
void G4OpenGLQtViewer::toggleBackground(bool check) {

  //   //I need to revisit the kernel if the background colour changes and
  //   //hidden line removal is enabled, because hlr drawing utilises the
  //   //background colour in its drawing...
  //   // (Note added by JA 13/9/2005) Background now handled in view
  //   // parameters.  A kernel visit is triggered on change of background.
  if (check == 1) {
    ((G4ViewParameters&)this->GetViewParameters()).
      SetBackgroundColour(G4Colour(1.,1.,1.));  // White
  } else {
    ((G4ViewParameters&)this->GetViewParameters()).
      SetBackgroundColour(G4Colour(0.,0.,0.));  // Black
  }
  updateQWidget();
}

/**
   SLOT Activate by a click on the transparency menu
@param check : 1 , 0
*/
void G4OpenGLQtViewer::toggleTransparency(bool check) {
  
  if (check) {
    transparency_enabled = false;
  } else {
    transparency_enabled = true;
  }
  SetNeedKernelVisit (true);
  updateQWidget();
}

/**
   SLOT Activate by a click on the antialiasing menu
@param check : 1 , 0
*/
void G4OpenGLQtViewer::toggleAntialiasing(bool check) {

  if (!check) {
    antialiasing_enabled = false;
    glDisable (GL_LINE_SMOOTH);
    glDisable (GL_POLYGON_SMOOTH);
  } else {
    antialiasing_enabled = true;
    glEnable (GL_LINE_SMOOTH);
    glHint (GL_LINE_SMOOTH_HINT, GL_NICEST);
    glEnable (GL_POLYGON_SMOOTH);
    glHint (GL_POLYGON_SMOOTH_HINT, GL_NICEST);
  }

  updateQWidget();
  printf("G4OpenGLQtViewer::toggleRepresentation %d\n",check);
}

/**
   SLOT Activate by a click on the haloing menu
@param check : 1 , 0
*/
//FIXME : I SEE NOTHING...
void G4OpenGLQtViewer::toggleHaloing(bool check) {
  if (check) {
    haloing_enabled = false;
  } else {
    haloing_enabled = true;
  }

  updateQWidget();

  printf("G4OpenGLQtViewer::toggleRepresentation %d\n",check);
}

/**
   SLOT Activate by a click on the auxiliaire edges menu
@param check : 1 , 0
*/
void G4OpenGLQtViewer::toggleAux(bool check) {
  if (check) {
    fVP.SetAuxEdgeVisible(false);
  } else {
    fVP.SetAuxEdgeVisible(true);
  }
  SetNeedKernelVisit (true);
  updateQWidget();

  printf("G4OpenGLQtViewer::toggleRepresentation %d\n",check);
}

/**
   SLOT Activate by a click on the full screen menu
@param check : 1 , 0
*/
void G4OpenGLQtViewer::toggleFullScreen(bool check) {
  GLWindow->setWindowState(GLWindow->windowState() ^ Qt::WindowFullScreen);

  printf("G4OpenGLQtViewer::toggleRepresentation %d\n",check);
}

/**
   SLOT Activate by a click on the mouse action menu
   @param check : 1 , 0
*/
void G4OpenGLQtViewer::toggleMouseAction(bool check) {
  if (check) { // rotate scene
    fMouseAction = true;
  } else { // move scene
    fMouseAction = false;
  }

  printf("G4OpenGLQtViewer::toggleRepresentation %d\n",check);
}


void G4OpenGLQtViewer::actionControlPanels() {
  printf("G4OpenGLQtViewer::actionControlPanels \n");
}

void G4OpenGLQtViewer::actionExitG4() {
  printf("G4OpenGLQtViewer::actionExitG4() \n");
}

void G4OpenGLQtViewer::actionCreateEPS() {
  QString nomFich = QFileDialog::getSaveFileName(GLWindow,
                                                 "Choisir un fichier",
                                                 ".", "Images (*.BMP *.GIF *.JPG *.JPEG *.PNG *.PBM *.PGM *.PPM *.TIFF *.XBM *.XPM)" );

  fWindow->grabFrameBuffer().save(nomFich);
  printf("G4OpenGLQtViewer::actionCreateEPS() \n");
}



/**
   Save the current mouse press point
   @param p mouse click point
*/
void G4OpenGLQtViewer::G4MousePressEvent(QPoint p)
{
  lastPos = p;
}

/**
   @param pos_x mouse x position
   @param pos_y mouse y position
   @param mButtons mouse button active
*/
void G4OpenGLQtViewer::G4MouseMoveEvent(int pos_x, int pos_y,Qt::MouseButtons mButtons)
{
  int dx = pos_x - lastPos.x();
  int dy = pos_y - lastPos.y();
  
  if (fMouseAction) {  // rotate
    if (mButtons & Qt::LeftButton) {
      //phi spin stuff here
      
      G4Vector3D vp = fVP.GetViewpointDirection ().unit ();
      G4Vector3D up = fVP.GetUpVector ().unit ();
      
      G4Vector3D yprime = (up.cross(vp)).unit();
      G4Vector3D zprime = (vp.cross(yprime)).unit();
      
      G4double delta_alpha;
      G4double delta_theta;
      
      if (fVP.GetLightsMoveWithCamera()) {
        delta_alpha = dy;
        delta_theta = -dx;
      } else {
        delta_alpha = -dy;
        delta_theta = dx;
      }    

      delta_alpha *= deg;
      delta_theta *= deg;

      G4Vector3D new_vp = std::cos(delta_alpha) * vp + std::sin(delta_alpha) * zprime;
      
      G4Vector3D new_up;
      if (fVP.GetLightsMoveWithCamera()) {
        new_up = (new_vp.cross(yprime)).unit();
        fVP.SetUpVector(new_up);
      } else {
        new_up = up;
      }
      ////////////////
      // Rotates by fixed azimuthal angle delta_theta.

      G4double cosalpha = new_up.dot (new_vp.unit());
      G4double sinalpha = std::sqrt (1. - std::pow (cosalpha, 2));
      yprime = (new_up.cross (new_vp.unit())).unit ();
      G4Vector3D xprime = yprime.cross (new_up);
      // Projection of vp on plane perpendicular to up...
      G4Vector3D a1 = sinalpha * xprime;
      // Required new projection...
      G4Vector3D a2 =
        sinalpha * (std::cos (delta_theta) * xprime + std::sin (delta_theta) * yprime);
      // Required Increment vector...
      G4Vector3D delta = a2 - a1;
      // So new viewpoint is...
      G4Vector3D viewPoint = new_vp.unit() + delta;

      fVP.SetViewAndLights (viewPoint);
      updateQWidget();
      
    } else if (mButtons & Qt::RightButton) {
      // NEVER DONE BECAUSE OF MOUSE MENU
      //       printf("G4OpenGLQtViewer::mouseMoveEvent Right \n");
      //       setXRotation(xRot + dy/2);
      //       setZRotation(zRot + dx/2);
      //       updateQWidget();
    }
  } else {  // move

    float dx = pos_x - lastPos.x();
    float dy = pos_y - lastPos.y();
    
    G4Point3D stp
      = GetSceneHandler()->GetScene()->GetStandardTargetPoint();
    
    G4Point3D tp = stp + fVP.GetCurrentTargetPoint ();
    
    const G4Vector3D& upVector = fVP.GetUpVector ();
    const G4Vector3D& vpVector = fVP.GetViewpointDirection ();
    
    G4Vector3D unitRight = (upVector.cross (vpVector)).unit();
    G4Vector3D unitUp    = (vpVector.cross (unitRight)).unit();
    
    tp += -dx * unitRight + dy * unitUp;
    fVP.SetCurrentTargetPoint (tp - stp);
    
    updateQWidget();
  }
  lastPos = QPoint(pos_x, pos_y);
}

#endif