[Paraview] Disappearing volume rendering?

[B.W.H. van Beest]

No, it doesn't work. The filter creates tets, which are visible in the
wireframe representation,
but when I select "Volume"  representation the image disappears.

I can't imagine it is so difficult to render a volume in Paraview. I
must be doing something wrong....

Regards,
Bertwim

On 10/13/2014 05:36 PM, Cory Quammen wrote:
> Bertwim,
>
> I'm not sure that the volume renderer can handle VTK_HEXAHEDRON
> elements. Try the "Tetrahedralize" filter on your source and see if
> the Volume representation works.
>
> Thanks,
> Cory
>
> On Mon, Oct 13, 2014 at 10:19 AM, B.W.H. van Beest <bwvb at xs4all.nl> wrote:
>> Hi,
>>
>> I'm struggling to get a proper 3D view of my model system (yes,
>> embarrassing!)
>> but must admit my defeat.
>> After stripping almost everything, keeping the minimum to exhibit the
>> issue,
>> I'm left with the following:
>>
>> I have created a simple box source. To get a 3D representation, I
>> sub-classed
>> the code for this Source from vtkUnstructuredGridAlgorithm.
>>
>> In the RequestData method, I define the 8 point of the unit cube. I
>> added the points to the
>> underlying unstructed grid, and I specified the cell topology.
>>
>> This all seems to work: when instantiating this box Source, I *do* get the
>> expected cube in the representations (Surface, wireframe, Points).
>>
>> However, when I select the "Volume" representation, *the image disappears*
>> What am I doing wrong?
>>
>> As the code is not too long and very simple, I take the freedom to paste
>> it below.
>>
>> 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 );
>>
>>    // Specify points.
>>    double r0[] = { 0.0, 0.0, 0.0 };
>>    double r1[] = { 1.0, 0.0, 0.0 };
>>    double r2[] = { 0.0, 1.0, 0.0 };
>>    double r3[] = { 1.0, 1.0, 0.0 };
>>    double r4[] = { 0.0, 0.0, 1.0 };
>>    double r5[] = { 1.0, 0.0, 1.0 };
>>    double r6[] = { 0.0, 1.0, 1.0 };
>>    double r7[] = { 1.0, 1.0, 1.0 };
>>
>>    // Collect the points in a vtk data structures.
>>    {
>>       vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();
>>       points->SetDataType( VTK_DOUBLE );
>>
>>       points->InsertNextPoint( r0 );
>>       points->InsertNextPoint( r1 );
>>       points->InsertNextPoint( r2 );
>>       points->InsertNextPoint( r3 );
>>       points->InsertNextPoint( r4 );
>>       points->InsertNextPoint( r5 );
>>       points->InsertNextPoint( r6 );
>>       points->InsertNextPoint( r7 );
>>
>>       // Transfer points to umesh.
>>       umesh->SetPoints( points );
>>    }
>>
>>    // Cell Topology
>>    vtkIdType vtx[8] = { 0, 1, 3, 2, 4, 5, 7, 6 };
>>    umesh->InsertNextCell( VTK_HEXAHEDRON, 8, vtx );
>>
>>    return 1;
>> }
>>
>>
>>
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