[vtkusers] Re: Using cell colors with point normals

[Nigel Nunn]

To:  Ron Inbar [ron at eun.co.il]] 
Re:  Using cell colors with point normals. 
Was: Getting vtkPolyDataRenderer to use both 
     cell data and point data. 
 
Hi Ron, 
I just faced a similar problem. 
Here is a first pass at a solution. 
Nigel. 
 
 
//------------------------------------------------ 
void CPANLDoc::UseCellValuesToColorPointData() 
//------------------------------------------------ 
{ 

  // Choose how to display the results.  

  if (m_bColorByPanelForces) 
    m_panelMapper->SetScalarModeToUseCellData(); 
  else 
    m_panelMapper->SetScalarModeToUsePointData(); 
 
 
  vtkUnstructuredGrid* pGrid = m_pVtkData->GetPanelGrid(); 
  vtkVectors *cellVecs = pGrid->GetCellData()->GetVectors(); 
  vtkScalars *cellData = pGrid->GetCellData()->GetScalars(); 
  vtkScalars *nodeData = pGrid->GetPointData()->GetScalars(); 
 
  //------------------------------------- 
  // First, update data for each CELL. 
  //------------------------------------- 

  double vec[3]; 

  for (i=1; i<=m_nPanels; ++i) 
  { 
    vec[0] = (float) m_FXPi(i,1); 
    vec[1] = (float) m_FYPi(i,1); 
    vec[2] = (float) m_FZPi(i,1); 
 
    cellVecs->SetVector(i-1, vec); 
  //cellData->SetScalar(i-1, 20 * m_FXPi(i,1)); 
  //cellData->SetScalar(i-1, 10 * m_FYPi(i,1)); 
    cellData->SetScalar(i-1, 10 * m_FZPi(i,1)); 
  } 
 
 
  //------------------------------------- 
  // Now update data for each NODE. 
  // (Allocating values for the PointData 
  // by averaging over cell values.) 
  //------------------------------------- 
 
  const int MAX_IDS_IN_CELL = 4; 
  
  int idc, nIDs; 
  double val=0.0; 
 
  vtkIdList *cellIds = vtkIdList::New(); 
  cellIds->Allocate(MAX_IDS_IN_CELL); 
 
  for (i=0; i<m_nNodes; ++i) 
  { 
    // Get list of CELLS that use this NODE 
    pGrid->GetPointCells(i, cellIds); 
 
    nIDs = cellIds->GetNumberOfIds(); 
    val=0.0; 
    for (int j=0; j < nIDs; ++j) 
    { 
      idc = cellIds->GetId(j); 
      val += cellData->GetScalar(idc); 
    } 
 
    val /= nIDs; 
 
    nodeData->SetScalar(i, val); 
  } 

 
  m_pVtkData->GetPanelGrid()->Modified(); 

  // Adjust colors in LookupTable 
  m_pVtkData->BuildLookupTable(); 
 
  this->UpdateAllViews(NULL,0,0); 
 
}