[vtkusers] Uneven colors after the vtkButterflySubdivisionFilter

[David Gobbi]

The vtkProbeFilter works fine with RGB scalars, doesn't it?  So it
should be possible to put a probe filter after the subdivision filter
to re-interpolate the scalars from the original data set.

On Sat, Apr 20, 2013 at 3:51 PM, Bill Lorensen <bill.lorensen at gmail.com> wrote:
> I was able to duplicate your problem. I believe the problem is trying to
> approximate the unsigned char 3-component colors. Butterfly is an
> approximating subdivision scheme, while loop is an interpolating scheme. I
> think if you assigned scalar float, single component values and mapper them
> through a lookup table you would get good results. But I'm not sure that
> would accomplish what you want.
>
>
>
> On Sat, Apr 20, 2013 at 2:23 PM, Bill Lorensen <bill.lorensen at gmail.com>
> wrote:
>>
>> This better. Just to be sure, I assume this code also produces bad
>> results?
>>
>>
>>
>> On Sat, Apr 20, 2013 at 1:39 PM, DivyaS <div.anand141 at gmail.com> wrote:
>>>
>>> Sure, please check this code - I have removed all the unnecessary code. I
>>> have added comments for each of the steps.
>>>
>>>             //Defining a cylinder source.
>>>             vtkCylinderSource cylinderSource = vtkCylinderSource.New();
>>>             cylinderSource.Update();
>>>
>>>             vtkTriangleFilter triangles = vtkTriangleFilter.New();
>>>             triangles.SetInput(cylinderSource.GetOutput());
>>>             triangles.Update();
>>>             vtkPolyData originalMesh;
>>>             originalMesh = triangles.GetOutput();
>>>
>>>             vtkUnsignedCharArray colors = vtkUnsignedCharArray.New();
>>>             colors.SetNumberOfComponents(3);
>>>             colors.SetNumberOfTuples(originalMesh.GetNumberOfPolys());
>>>             colors.SetName("Colors");
>>>
>>>             //Creating an array to store the values according to which
>>> the
>>> colors are selected.
>>>             //Values are inserted for each of the points in the polydata
>>>             int[] colorAT = new int[originalMesh.GetNumberOfPolys()];
>>>             for (int i = 0; i < originalMesh.GetNumberOfPolys(); i++)
>>>             {
>>>                 colorAT[i] = i;
>>>             }
>>>
>>>             int activationTime;
>>>             //Loop to select colors for each of the points in the
>>> polydata.
>>>             for (int i = 0; i < originalMesh.GetNumberOfPolys(); i++)
>>>             {
>>>                 activationTime = colorAT[i];
>>>                 if (activationTime > 0 && activationTime < 5)
>>>                 {
>>>                     //Black
>>>                     colors.InsertTuple3(i, 255, 255, 0);
>>>                 }
>>>                 else if (activationTime > 4 && activationTime < 10)
>>>                 {
>>>                     //Blue
>>>                     colors.InsertTuple3(i, 0, 0, 255);
>>>                 }
>>>                 else if (activationTime > 9 && activationTime < 300)
>>>                 {
>>>                     //Red
>>>                     colors.InsertTuple3(i, 255, 0, 0);
>>>                 }
>>>             }
>>>             originalMesh.GetPointData().SetScalars(colors);
>>>
>>>             //Subdivision.
>>>             int numberOfSubdivisions = 4;
>>>             vtkPolyDataAlgorithm subdivisionFilter =
>>> vtkButterflySubdivisionFilter.New();
>>>
>>>
>>> ((vtkButterflySubdivisionFilter)subdivisionFilter).SetNumberOfSubdivisions(numberOfSubdivisions);
>>>             subdivisionFilter.SetInput(originalMesh);
>>>             subdivisionFilter.Update();
>>>
>>>             vtkRenderWindow renderWindow =
>>> renderWindowControl1.RenderWindow;
>>>             vtkRenderer renderer = vtkRenderer.New();
>>>
>>>             //Create a mapper and actor
>>>             vtkPolyDataMapper mapper = vtkPolyDataMapper.New();
>>>             mapper.SetInputConnection(subdivisionFilter.GetOutputPort());
>>>             vtkActor actor = vtkActor.New();
>>>             actor.SetMapper(mapper);
>>>
>>>             renderer.AddActor(actor);
>>>             renderer.SetBackground(0, 0, 0);
>>>             renderer.ResetCamera();
>>>             renderWindow.AddRenderer(renderer);
>>>             renderWindow.Render();
>>>
>>>
>>>