VTK屏幕坐标与世界坐标转换(Qt)

void VtkMPRWidget::mousePressEvent( QMouseEvent* event )
{
 m_bPressed = true;
 m_pressPoint = event->pos();
}

void VtkMPRWidget::mouseMoveEvent( QMouseEvent* event )
{
 if( !m_bPressed )
  return;
 m_movePoint = event->pos();
 int nHeight = height();
 double* dPressValue;
 double* dMoveValue;
 vtkSmartPointer<vtkCoordinate> pCoorPress = vtkSmartPointer<vtkCoordinate>::New();
 pCoorPress->SetCoordinateSystemToDisplay();
 pCoorPress->SetValue( m_pressPoint.x(), nHeight - m_pressPoint.y(), 0.0 );
 dPressValue = pCoorPress->GetComputedWorldValue( m_pRenderer );
 vtkSmartPointer<vtkCoordinate> pCoorMove = vtkSmartPointer<vtkCoordinate>::New();
 pCoorMove->SetCoordinateSystemToDisplay();
 pCoorMove->SetValue( m_movePoint.x(), nHeight - m_movePoint.y(), 0.0 );
 dMoveValue = pCoorMove->GetComputedWorldValue( m_pRenderer );
 double dPressVal[3] = { dPressValue[0], dPressValue[1], dPressValue[2] };
 double dMoveVal[3] = { dMoveValue[0], dMoveValue[1], dMoveValue[2] };
 vtkSmartPointer<vtkPoints> pPoints = vtkSmartPointer<vtkPoints>::New();
 pPoints->InsertNextPoint( dPressVal[0], dPressVal[1], 0.0 );
 pPoints->InsertNextPoint( dPressVal[0], dMoveVal[1], 0.0 );
 pPoints->InsertNextPoint( dMoveVal[0], dMoveVal[1], 0.0 );
 pPoints->InsertNextPoint( dMoveVal[0], dPressVal[1], 0.0 );
 vtkSmartPointer<vtkLine> line1 = vtkSmartPointer<vtkLine>::New();
 line1->GetPointIds()->SetId( 0, 0 );
 line1->GetPointIds()->SetId( 1, 1 );
 vtkSmartPointer<vtkLine> line2 = vtkSmartPointer<vtkLine>::New();
 line2->GetPointIds()->SetId( 0, 1 );
 line2->GetPointIds()->SetId( 1, 2 );
 vtkSmartPointer<vtkLine> line3 = vtkSmartPointer<vtkLine>::New();
 line3->GetPointIds()->SetId( 0, 2 );
 line3->GetPointIds()->SetId( 1, 3 );
 vtkSmartPointer<vtkLine> line4 = vtkSmartPointer<vtkLine>::New();
 line4->GetPointIds()->SetId( 0, 3 );
 line4->GetPointIds()->SetId( 1, 0 );
 vtkSmartPointer<vtkCellArray> lineArray = vtkSmartPointer<vtkCellArray>::New();
 lineArray->InsertNextCell( line1 );
 lineArray->InsertNextCell( line2 );
 lineArray->InsertNextCell( line3 );
 lineArray->InsertNextCell( line4 );
 if( NULL == m_pPolyData )
 {
  m_pPolyData = vtkSmartPointer<vtkPolyData>::New();
  m_pPolyData->SetPoints( pPoints );
  m_pPolyData->SetLines( lineArray );
  m_pPolyData->Modified();
  vtkSmartPointer<vtkPolyDataMapper> mapper = vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper->SetInputData( m_pPolyData );
  vtkSmartPointer<vtkActor> actor = vtkSmartPointer<vtkActor>::New();
  actor->SetMapper( mapper );
  actor->GetProperty()->SetLineWidth( 1.5 );
  actor->GetProperty()->SetColor( 0.3, 0.8, 0.0 );
  m_pRenderer->AddActor( actor );
  m_pRenderer->Modified();
  m_pRednerWindow->Modified();
  m_pRednerWindow->Render();
  return;
 }
 m_pPolyData->SetPoints( pPoints );
 m_pPolyData->SetLines( lineArray );
 m_pPolyData->Modified();
 m_pRednerWindow->Modified();
 m_pRednerWindow->Render();
}

void VtkMPRWidget::mouseReleaseEvent( QMouseEvent* event )
{
 m_bPressed = false;
 m_pPolyData = NULL;
 //FireObjectChanged();
}