[vtk-developers] Should vtkClipPolyData keep the normals?

[Karthik Krishnan]

You are missing vtkTypeRevisionMacro. There's stuff in debug leaks
that relies on methods that the macro defines....

Try adding....


class VTK_FILTERING_EXPORT vtkNoMergePointLocator: public vtkPointLocator
{
public:
  vtkTypeRevisionMacro( vtkNoMergePointLocator, vtkLocator );
};

vtkCxxRevisionMacro(vtkNoMergePointLocator, "$Revision: 1.7 $");

And please let us know if it works for you.

Thanks
--
karthik

On Thu, Sep 11, 2008 at 1:26 PM, Mathieu Coursolle
<mcoursolle at rogue-research.com> wrote:
> Hi,
> Maybe I missed something then... Here is what my class looks like:
> class VTK_FILTERING_EXPORT vtkNoMergePointLocator: public vtkPointLocator
> {
> protected:
>
> vtkNoMergePointLocator();
> virtual ~vtkNoMergePointLocator();
> public:
> static vtkNoMergePointLocator* New();
> virtual int InsertUniquePoint(const double inPoint[3], vtkIdType& outId);
> };
> // ----------------------------------------------------
> vtkStandardNewMacro(vtkNoMergePointLocator);
> // ----------------------------------------------------
> vtkNoMergePointLocator::vtkNoMergePointLocator()
> {
> }
> // ----------------------------------------------------
> vtkNoMergePointLocator::~vtkNoMergePointLocator()
> {
> }
> // ----------------------------------------------------
> int vtkNoMergePointLocator::InsertUniquePoint(const double x[3], vtkIdType
> &ptID)
> {
> ptID = this->InsertNextPoint(x);
> return 1;
> }
> And I use it like this:
> vtkNoMergePointLocator* locator = vtkNoMergePointLocator::New();
>
> vtkSmartPointer<vtkClipPolyData> clipper =
> vtkSmartPointer<vtkClipPolyData>::New();
> clipper->SetInput(mesh);
> clipper->SetClipFunction(aBox);
> clipper->SetGenerateClippedOutput(0);
> clipper->SetInsideOut(1);
> clipper->SetLocator(locator);
> clipper->Update();
> mesh = clipper->GetOutput();
> locator->Delete();
> When I call Delete(), a waning is raised:
> Generic Warning: In
> /Volumes/Extra/Kitware/VTK/Latest/VTK/Common/vtkDebugLeaks.cxx, line 296
> Deleting unknown object: vtkPointLocator
> Then the object leaks when my application closes:
> vtkDebugLeaks has detected LEAKS!
> Class "vtkNoMergePointLocator" has 1 instance still around.
> Am I missing something?
> Thanks!
> Mathieu
> On 11-Sep-08, at 12:27 PM, Karthik Krishnan wrote:
>
> On Thu, Sep 11, 2008 at 11:49 AM, Mathieu Coursolle
> <mcoursolle at rogue-research.com> wrote:
>
> Hi,
>
> Thanks a lot, it works just as expected!
>
> It brings some other questions though. I overloaded vtkPointLocator and
>
> created
>
> a vtkNoMergePointLocator with the suggested changes.
>
> I did not add that class to VTK, but to my project. However, vtkDebugLeaks
>
> complains
>
> it does not know the class, and so that object leaks.
>
>
> That should not matter as far as vtkDebugLeaks is concerned. I think
> something else is going on.
>
> --
> karthik
>
>
> 1) Is there a way to give knowledge of my new class to vtkDebugLeaks?
>
> 2) Should just a class find its way into VTK?
>
> Thanks!
>
> Mathieu
>
> On 10-Sep-08, at 4:54 PM, Berk Geveci wrote:
>
> I know what the problem is. vtkClipPolyData does copy the normals. The
>
> reason you are seeing artifacts is due to the fact that
>
> vtkClipPolyData merges coincident points. This produces the effect you
>
> are seeing where there are sharp angles. You can fix this problem by
>
> subclassing vtkPointLocator, making sure that this subclass does not
>
> merge points and pass it to vtkClipPolyData::SetLocator(). So this
>
> class would have something like:
>
> int vtkMyPointLocator::InsertUniquePoint(const double x[3], vtkIdType &id)
>
> {
>
> id = this->InsertNextPoint(x);
>
> return 1;
>
> }
>
> You code would have
>
> vtkMyPointLocator* lc = vtkPointLocator::New();
>
> clipper->SetLocator(lc);
>
> -berk
>
>
> On Wed, Sep 10, 2008 at 9:47 AM, Mathieu Coursolle
>
> <mcoursolle at rogue-research.com> wrote:
>
> Hi,
>
> Here is a more detailed description of the issue:
>
> I loaded 42400-IDGH.stl from the VTKData folder using vtkSTLReader.
>
> I then use the following code to compute the normals, as none are read:
>
> vtkSmartPointer<vtkPolyDataNormals> normalsFilter =
>
> vtkSmartPointer<vtkPolyDataNormals>::New();
>
> normalsFilter->SetInput(myPolyData);
>
> normalsFilter->SetFeatureAngle(60.0);
>
> normalsFilter->Update();
>
> myPolyData = normalsFilter->GetOutput();
>
> Then, if I display this polydata, the result looks just fine (see
>
> attachment). However, if I apply the vtkClipPolyData filter
>
> using an implicit function that includes the entire polydata, the normals
>
> are lost:
>
> vtkSmartPointer<vtkClipPolyData> clipper =
>
> vtkSmartPointer<vtkClipPolyData>::New();
>
> clipper->SetInput(myPolyData);
>
> clipper->SetClipFunction(aBox);
>
> clipper->SetGenerateClippedOutput(0);
>
> clipper->SetInsideOut(1);
>
> clipper->Update();
>
> myPolyData = clipper->GetOutput();
>
> Would it be easy to change the filter to add an option to keep the
>
> normals,
>
> and to compute the missing ones?
>
> Sure I can call the normals filter after the clip filter, but some of my
>
> data have specific normals I need to keep, and
>
> calling a normals filter after the clipping modifies them. Since I have
>
> no
>
> knowledge on how those normals were created,
>
> I need to keep them for the untouched cells.
>
> See attachment on the effect of the clipping process.
>
> Thanks!
>
> Mathieu
>
> On 9-Sep-08, at 4:44 PM, Berk Geveci wrote:
>
> Something is fishy there. The line you added is copying the point data
>
> onto itself.
>
> vtkPointData *inPD=input->GetPointData(), *outPD =
>
> output->GetPointData();
>
> ....
>
> output->GetPointData()->PassData(outPD);
>
> That PassData() should not do anything at best and may corrupt the
>
> output data at worst. Can you post a small example demonstrating the
>
> issue?
>
> -berk
>
>
> 2008/9/9 Mathieu Coursolle <mcoursolle at rogue-research.com>:
>
> Hi VTK developers,
>
> I am using vtkClipPolyData to clip a vtkPolyData with an implicit
>
> function
>
> (vtkBox).
>
> The origin vtkPolyData has specific normals I want to keep for the
>
> resulting
>
> polydata.
>
> Unfortunately, the normals are not the same in the output polydata.
>
> I looked at the code, and I have a question regarding the creation of the
>
> output polydata:
>
> For the Clipped Output, the PassData() method and the Squeeze() method
>
> are
>
> called one
>
> the points, lines, polys, strips are set. This is not true for the
>
> standard
>
> output. Is there a reason?
>
> Shouldn't the code be:
>
> if (newVerts->GetNumberOfCells())
>
> {
>
> output->SetVerts(newVerts);
>
> }
>
> newVerts->Delete();
>
> if (newLines->GetNumberOfCells())
>
> {
>
> output->SetLines(newLines);
>
> }
>
> newLines->Delete();
>
> if (newPolys->GetNumberOfCells())
>
> {
>
> output->SetPolys(newPolys);
>
> }
>
> newPolys->Delete();
>
>
>
> output->GetPointData()->PassData(outPD);      <<<<<<<<<< ADDED CODE
>
> <<<<<<<<<<<<
>
> output->Squeeze();                            <<<<<<<<<< ADDED CODE
>
> <<<<<<<<<<<<
>
> if ( this->GenerateClippedOutput )
>
> {
>
> this->GetClippedOutput()->SetPoints(newPoints);
>
> if (clippedVerts->GetNumberOfCells())
>
>   {
>
>   this->GetClippedOutput()->SetVerts(clippedVerts);
>
>   }
>
> clippedVerts->Delete();
>
> if (clippedLines->GetNumberOfCells())
>
>   {
>
>   this->GetClippedOutput()->SetLines(clippedLines);
>
>   }
>
> clippedLines->Delete();
>
> if (clippedPolys->GetNumberOfCells())
>
>   {
>
>   this->GetClippedOutput()->SetPolys(clippedPolys);
>
>   }
>
> clippedPolys->Delete();
>
>
>
> this->GetClippedOutput()->GetPointData()->PassData(outPD);
>
> this->GetClippedOutput()->Squeeze();
>
> }
>
> It seems to work alright with that fix, but I am not too sure of what it
>
> is
>
> doing...
>
> Thanks!
>
> Mathieu
>
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-- 
Karthik Krishnan
R&D Engineer,
Kitware Inc.
Ph: 518 371 3971 x119
Fax: 518 371 3971