[vtkusers] VTK polylines using RGBA to set opacity does not work

[Reicht Ignaz]

Hi,

on creating vtk polylines with RGBA-color information for each single point, no opacity has been processed/rendered. VTK-Literature says that opacity can be specified for an actor and also for an vertex, but somehow this does not work properly for vertex based settings. Attached you will find my code example where two polylines are given. coordinates represent polyline1 in front of polyline2. Color/opacity-information is given using RGBA tuple with 4 Components. I also tried this approach using vtkTubes but with the same disappointing result (see commented out parts).

Does somebody know what is missing or what is implemented wrong?
thanks in advise
iggy

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int main() {



   //Create points for polyline1.
  double origin[3] = {0.0, 0.0, 0.0};
  double p0[3] = {100.0, 0.0, 0.0};
  double p1[3] = {150.0, 100.0, 0.0};
  double p2[3] = {170.0, 200.0, 0.0};



  //create points for polyline2
  double p01[3] = {50.0, 50.0, 13.0};
  double p11[3] = {200.0, 100.0, 13.0};

  //insert points to vtkPointarray
  vtkPoints *pnts = vtkPoints::New();
  pnts->InsertPoint(0,origin);
  pnts->InsertPoint(1,p0);
  pnts->InsertPoint(2,p1);
  pnts->InsertPoint(3,p2);
  pnts->InsertPoint(4,p01);
  pnts->InsertPoint(5,p11);



  //generate and define polyline1
  vtkPolyLine *polyLine = vtkPolyLine::New();
  polyLine->GetPointIds()->SetNumberOfIds(4);
  polyLine->GetPointIds()->SetId(0,0);
  polyLine->GetPointIds()->SetId(1,1);
  polyLine->GetPointIds()->SetId(2,2);
  polyLine->GetPointIds()->SetId(3,3);



  //generate and define polyline2
  vtkPolyLine *polyLine2 = vtkPolyLine::New();
  polyLine2->GetPointIds()->SetNumberOfIds(2);
  polyLine2->GetPointIds()->SetId(0,4);
  polyLine2->GetPointIds()->SetId(1,5);

  //add lines to cellArray

  vtkCellArray *lines = vtkCellArray::New();
  lines->InsertNextCell(polyLine);
  lines->InsertNextCell(polyLine2);



  vtkPolyData *polyDataT = vtkPolyData::New();
  polyDataT->SetPoints(pnts);
  polyDataT->SetLines(lines);



  //color and opacity handling
  vtkUnsignedCharArray *colorT = vtkUnsignedCharArray::New();
  colorT->SetName("Colors");
  colorT->SetNumberOfComponents(4); //4 components cuz of RGBA



  unsigned char red[4] =      {255, 0,    0,    0.5};
  unsigned char green[4] =    {0,   255,  0,    0.5};
  unsigned char blue[4] =     {0,   0,    255,  0.5};
  unsigned char white[4] = {255, 255, 255,   0.5};

  colorT->InsertNextTupleValue(red); //color for point0
  colorT->InsertNextTupleValue(green); //color for point1
  colorT->InsertNextTupleValue(blue);
  colorT->InsertNextTupleValue(white);
  colorT->InsertNextTupleValue(white);
  colorT->InsertNextTupleValue(white); //color for point5



  polyDataT->GetPointData()->AddArray(colorT);



  //tube representation

  //vtkTubeFilter *tube =  vtkTubeFilter::New();
  //tube->SetInput(polyDataT);
  //tube->SetNumberOfSides(8);
  //tube->SetRadius(5);



  vtkSmartPointer<vtkPolyDataMapper> mapper =
  vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper->SetInput(polyDataT);
  //mapper->SetInputConnection(tube->GetOutputPort()); //using for tube representation
  mapper->ScalarVisibilityOn();
  mapper->SetScalarModeToUsePointFieldData();
  mapper->SelectColorArray("Colors");



  vtkSmartPointer<vtkActor> actor =
  vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);



  //Rendering

  vtkSmartPointer<vtkRenderer> renderer =
  vtkSmartPointer<vtkRenderer>::New();
  renderer->AddActor(actor);
  renderer->SetBackground(.2, .3, .4);

  renderer->ResetCamera();

  vtkSmartPointer<vtkRenderWindow> renWin =
  vtkSmartPointer<vtkRenderWindow>::New();
  vtkSmartPointer<vtkRenderWindowInteractor>
  iren = vtkSmartPointer<vtkRenderWindowInteractor>::New();
  iren->SetRenderWindow(renWin);
  renWin->AddRenderer(renderer);
  renWin->SetSize(500, 500);
  renWin->Render();
  iren->Start();

}//end main()
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