[vtkusers] RGB colours for many lines in vtkPolyData

[Arkadiusz Zychewicz]

Hi,
  I have to display many lines (~10000) and each one must have different
colour.  For now I use scalar colour for that, but I cannot represent
black or white colour. I  want to adopt the lookupTable but I cannot
figure out how it works.


   vtkPoints* m_points = vtkPoints::New();
   vtkCellArray*m_lines = vtkCellArray::New();
   vtkFloatArray* m_lineScalars = vtkFloatArray::New();
   vtkLookupTable* m_lookupTable = vtkLookupTable::New();

int m_curPointID = 0
for(int i = 0; i < lines.size(); i++){
    m_lineScalars->SetNumberOfComponents(1);
    m_points->InsertNextPoint(lines.getStart());
    m_lineScalars->InsertNextTuple1(scalar); //this gives colour
                             // exp.: (r*256*256+g*256+b)/0xffffff
    m_points->InsertNextPoint(lines.getEnd());
    m_lineScalars->InsertNextTuple1(scalar);

    m_lines->InsertNextCell(2);
    m_lines->InsertCellPoint(m_curPointID);
    m_lines->InsertCellPoint(m_curPointID + 1);
    m_curPointID += 2;

}
   m_lookupTable->SetNumberOfColors(0xffffff);
    m_lookupTable->SetNumberOfTableValues(0xffffff);
    m_lookupTable->Build();
    int size = 0xff;
    for (int ir = 0; ir < size; ir++) {
        for (int ig = 0; ig < size; ig++) {
            for (int ib = 0; ib < size; ib++) {
                double r = ir / (double) size;
                double g = ig / (double) size;
                double b = ib / (double) size;
                m_lookupTable->SetTableValue(ir * size * size + ig *
size + ib, r, g, b);
            }
        }
    }

    m_lookupTable->SetTableRange(0, 1);


    // Create poly data
    vtkPolyData* polyData = vtkPolyData::New();
    polyData->SetPoints(m_points);
    polyData->SetLines(m_lines);
    polyData->GetPointData()->SetScalars(m_lineScalars);