Problem with vtkClipPolyData

[Bill Lorensen]

Paul,
         As usual, thanks for the explicit bug report with an example. I found the problem and the fix will appear in tonight's build. I'm also adding your example as a regression test.

Bill

At 08:32 PM 3/24/00 -0800, pahsieh at usgs.gov wrote:
>I am running into a problem with vtkClipPolyData when the
>dataset contains cell scalars. The filter does not seem to
>work correctly with GenerateClippedOutputOn, but
>works fine with GenerateClippedOutputOff.
>
>This problem is illustrated by the attached sample code.
>A structured points data set is created with cell scalars,
>and is then passed through a geometry filter to obtain
>a poly dataset for clipping.
>
>Clipping is done twice on the poly dataset, the first time
>with GenerateClippedOutputOn, and the second time with
>GenerateClippedOutputOff. The resulting actors are different.
>
>This problem occurs in both vtk 2.3 and vtk 3.1 ("official"
>release). The problem also occurs when the clipped dataset is
>a structured grid that has been passed through a geometry filter,
>or a poly data created from scratch.
>
>Thanks for any help and best regards,
>-- Paul
>
>//======= sample code =======
>
>#include "vtkRenderer.h"
>#include "vtkRenderWindow.h"
>#include "vtkRenderWindowInteractor.h"
>#include "vtkStructuredPoints.h"
>#include "vtkGeometryFilter.h"
>#include "vtkPlane.h"
>#include "vtkClipPolyData.h"
>#include "vtkPolyDataMapper.h"
>#include "vtkActor.h"
>
>void main()
>{
>     // Create the rendering stuff
>     vtkRenderer *ren = vtkRenderer::New();
>     vtkRenderWindow *renWin = vtkRenderWindow::New();
>     renWin->AddRenderer(ren);
>     vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
>     iren->SetRenderWindow(renWin);
>
>     // Create a structured points data set
>     vtkStructuredPoints *sp = vtkStructuredPoints::New();
>     sp->SetDimensions(11, 11, 1);
>     sp->SetSpacing(1, 1, 1);
>     sp->SetOrigin(0, 0, 0);
>
>     // Create some cell scalar data.
>     vtkScalars *scalars = vtkScalars::New();
>     for (int i=0; i<100; i++)
>     {
>         scalars->InsertNextScalar(0.01 * i);
>     }
>     sp->GetCellData()->SetScalars(scalars);
>     scalars->Delete();
>
>     // Use the geometry filter to make a poly data set.
>     vtkGeometryFilter *geom = vtkGeometryFilter::New();
>     geom->SetInput(sp);
>
>     // Define the clipping plane x = 2.5
>     vtkPlane *plane = vtkPlane::New();
>     plane->SetNormal(1, 0, 0);
>     plane->SetOrigin(2.5, 0, 0);
>
>     // Clip the data with GenerateClippedOutputOn
>     vtkClipPolyData *clip1 = vtkClipPolyData::New();
>     clip1->SetInput(geom->GetOutput());
>     clip1->SetClipFunction(plane);
>     clip1->GenerateClippedOutputOn();
>
>     vtkPolyDataMapper *mapper1 = vtkPolyDataMapper::New();
>     mapper1->SetInput(clip1->GetOutput());
>     mapper1->SetScalarModeToUseCellData();
>
>     vtkActor *actor1 = vtkActor::New();
>     actor1->SetMapper(mapper1);
>
>     // Clip the same date with GenerateClippedOutputOff
>     vtkClipPolyData *clip2 = vtkClipPolyData::New();
>     clip2->SetInput(geom->GetOutput());
>     clip2->SetClipFunction(plane);
>     clip2->GenerateClippedOutputOff();
>
>     vtkPolyDataMapper *mapper2 = vtkPolyDataMapper::New();
>     mapper2->SetInput(clip2->GetOutput());
>     mapper2->SetScalarModeToUseCellData();
>
>     vtkActor *actor2 = vtkActor::New();
>     actor2->SetMapper(mapper2);
>     actor2->AddPosition(12, 0, 0);
>
>
>     // Display the 2 actors
>     ren->AddActor(actor1);
>     ren->AddActor(actor2);
>     renWin->Render();
>     iren->Start();
>
>     // Clean up
>     sp->Delete();
>     geom->Delete();
>     plane->Delete();
>     clip1->Delete();
>     mapper1->Delete();
>     actor1->Delete();
>     clip2->Delete();
>     mapper2->Delete();
>     actor2->Delete();
>     ren->Delete();
>     renWin->Delete();
>     iren->Delete();
>}


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