[vtkusers] vtkCutter on unstructured grid overwrites cell data (VTK 4.4)

[John Platt]

Hi Users,

 

I think there is a problem colour mapping cell scalars using vtkCutter
on an unstructured grid. The grid contains 2 cells, a hex and a quad.

Cutting the hex creates 2 triangles - vtkHexahedron::Contour() calls 

 

      newCellId = polys->InsertNextCell(3,pts);

      outCd->CopyData(inCd,cellId,newCellId);

 

creating new triangles with newCellId =  0 & 1.

 

Cutting the quad gives a single line - vtkQuad::Contour() calls

 

      newCellId = lines->InsertNextCell(2,pts);

      outCd->CopyData(inCd,cellId,newCellId);

 

creating a new line with newCellId =  0.

 

Unfortunately, the CopyData() in vtkQuad::Contour() overwrites the cell
data for the first triangle. On more complex geometries this causes the
renderer to crash because the cell data is not present.

 

I think the calls to copy the cell data need the new cell Id in the
aggregate polydata, not the individual lines or polys - something like

 

      outCD->CopyData(inCd, cellId, vtkCutter->NumberOfNewCells++ );

 

Any suggestions for a resolution would be very much appreciated.

 

John.

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