[Paraview] Export to vtk file needed to get colours!
B.W.H. van Beest
bwvb at xs4all.nl
Tue Oct 14 17:01:31 EDT 2014
Yes, that works!
Now the box comes up immediately, in coloured form.
Thanks!
Bertwim
On 10/14/2014 10:28 PM, Cory Quammen wrote:
> Bertwim,
>
> Try naming your arrays, e.g.
>
> vtxdata->SetName("Point Scalars");
> vxldata->SetName("Cell Scalars");
>
> and see if that makes them appear in the Coloring combo box.
>
> Thanks,
> Cory
>
> On Tue, Oct 14, 2014 at 4:23 PM, B.W.H. van Beest <bwvb at xs4all.nl
> <mailto:bwvb at xs4all.nl>> wrote:
>
> Hello All,
>
> I wonder if I stumbled upon a bug, or if I made a thinking error
> myself.
>
> The issue is: I can get colouring of my Source object only after I
> write
> it first to a vtk file and then read it back again!
>
> This is what I do:
>
> -) I create a single (rectangular) 3D cell from a (handcrafted)
> Source type,
> subclassed from vtkUnstructuredGridAlgorithm.
> This cell has scalar properties assigned to both its vertices
> as well as the cell itself.
>
> -) After "Apply", the box becomes visible (surface representation)
> However, there are no colours. The "Coloring" section in the
> Properties panel does not show the scalar properties. Only
> "Solid Color" and "cellNormals" appear as combo-options.
>
> -) After writing the model to a vtk file, and loading the
> latter, the
> loaded box does appear in its coloured form, with the scalar
> properties
> selectable in the "Coloring" combo box.
>
> Why do the colours not show up immediately after I created
> ("Apply") the
> source object. I naively tried a Modified() on the underlying
> unstructed grid object,
> but that didn't help.
>
> For completeness, I paste the relevant code as well as the vtk
> file (ascii).
>
> Kind Regards,
> Bertwim
>
>
>
> ====================
> int sphBoxSourceC::RequestData( vtkInformation *vtkNotUsed(request),
> vtkInformationVector
> **vtkNotUsed(inputVector),
> vtkInformationVector *outputVector)
> {
> // Get the info object
> vtkInformation *outInfo = outputVector->GetInformationObject(0);
> vtkUnstructuredGrid *umesh = vtkUnstructuredGrid::SafeDownCast(
> outInfo->Get( vtkDataObject::DATA_OBJECT() ) );
>
> // Pre-allocate some memory
> umesh->Allocate( 1024 );
>
> // Scalars for the property values
> vtkFloatArray* vtxdata = vtkFloatArray::New(); // property
> defined on a vertex.
> vtkFloatArray* vxldata = vtkFloatArray::New(); // property
> defined in a voxel.
>
> // Specify points.
> float r0[] = { 0.0, 0.0, 0.0 };
> float r1[] = { 1.0, 0.0, 0.0 };
> float r2[] = { 0.0, 1.0, 0.0 };
> float r3[] = { 1.0, 1.0, 0.0 };
> float r4[] = { 0.0, 0.0, 1.0 };
> float r5[] = { 1.0, 0.0, 1.0 };
> float r6[] = { 0.0, 1.0, 1.0 };
> float r7[] = { 1.0, 1.0, 1.0 };
>
> // Collect the points in a vtk data structures.
> {
> vtkSmartPointer<vtkPoints> points =
> vtkSmartPointer<vtkPoints>::New();
> points->SetDataType( VTK_FLOAT );
>
> points->InsertNextPoint( r0 ); vtxdata->InsertNextValue(
> cos(0.1) );
> points->InsertNextPoint( r1 ); vtxdata->InsertNextValue(
> cos(0.4) );
> points->InsertNextPoint( r2 ); vtxdata->InsertNextValue(
> cos(0.7) );
> points->InsertNextPoint( r3 ); vtxdata->InsertNextValue(
> cos(1.0) );
> points->InsertNextPoint( r4 ); vtxdata->InsertNextValue(
> cos(1.3) );
> points->InsertNextPoint( r5 ); vtxdata->InsertNextValue(
> cos(1.6) );
> points->InsertNextPoint( r6 ); vtxdata->InsertNextValue(
> cos(1.9) );
> points->InsertNextPoint( r7 ); vtxdata->InsertNextValue(
> cos(2.2) );
>
> // Transfer points to umesh.
> umesh->SetPoints( points );
> umesh->GetPointData()->SetScalars( vtxdata );
> }
>
> // Cell Topology
> vtkIdType vtx[8] = { 0, 1, 3, 2, 4, 5, 7, 6 };
> umesh->InsertNextCell( VTK_HEXAHEDRON, 8, vtx );
> vxldata->InsertNextValue( 3.14 );
> umesh->GetCellData()->SetScalars( vxldata );
>
> // Write data to a file
> {
> std::string fileName( "myfile.vtk" );
> V3D::Utils::WriteUMesh( umesh, "Rectangular block as umesh",
> fileName, VTK_ASCII );
> cerr << "Created: " << fileName << std::endl;
> }
>
> vtxdata->Delete();
> vxldata->Delete();
>
> return 1;
> }
>
> =======================
> The file "myfile.vtk", written above read:
> =======================
> # vtk DataFile Version
> 3.0
>
> Rectangular block as
> umesh
>
> ASCII
>
> DATASET
> UNSTRUCTURED_GRID
>
> POINTS 8
> float
>
> 0 0 0 1 0 0 0 1
> 0
>
> 1 1 0 0 0 1 1 0
> 1
>
> 0 1 1 1 1
> 1
>
> CELLS 1
> 9
>
> 8 0 1 3 2 4 5 7
> 6
>
>
>
> CELL_TYPES
> 1
>
> 12
>
>
>
> CELL_DATA
> 1
>
> SCALARS scalars
> float
>
> LOOKUP_TABLE
> default
>
> 3.14
>
> POINT_DATA
> 8
>
> SCALARS scalars
> float
>
> LOOKUP_TABLE
> default
>
> 0.995004 0.921061 0.764842 0.540302 0.267499 -0.0291995 -0.32329
> -0.588501
>
> =======================
>
>
>
>
>
>
>
>
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