CropPolyData for a new "Surface Patch Selection Widget"

Hi Developers

I am trying to create a widget similar to the vtkContourWidget for selecting vtkPolyData along a contour. For this, I created a new implicit function for clipping, vtkCapsule

When updating the contour, I use vtkExtractPolyData using implicit functions for each line segment. My current approach is maintain an instance of vtkPolyData that is updated using vtkAppendPolyData and every now and then I remove duplicate cells using a vtkCleanPolyData.

It doesn’t scale very well for large meshes. Is it somehow possible to reduce the UPDATE_EXTENT such that the implicit functions only are applied on a subset of the large mesh. I am thinking of a filter that I can squeeze in between my source for vtkPolyData and vtkExtractPolyData. I am thinking about a "vtkPolyDataCropFilter. I tried setting UPDATE_EXTENTon the output information, but that just get updated toWHOLE_EXTENT` when executing the pipeline.

It is probably just me not knowing the name of the correct filter.

Thanks in advance
Jens Munk