[vtkusers] Filter to merge several lines into a single polyline?

[Amy Henderson]

Hi Jean-Do,

Try passing the results of vtkCutter through vtkStripper.

- Amy

At 04:04 PM 5/11/2004, Jean-Dominique Barnichon wrote:
>Hello,
>
>As a result of applying a vtkCutter filter to a 3D surface (see code snippet
>below), I obtain a vtkPolyData object that is made of :
>  - a set of points,
>  - a set of lines (7 in the example below, see ouput below).
>
>You can notice that output lines share end points, i.e. they could 'easily'
>all be converted into a single polyline (in the exmaple shown below, this
>could be done starting backward from the last line, but I don't known this
>can always be done this way).
>
>All I need is converting this set of 'jointive' lines into a single
>polyline.
>Is there any filter that can do that? Or do I have to write one by myself?
>
>Any answer/hint is welcome.
>Note that applying vtkCleanPolyData is pointless here as there are already
>no duplicate points.
>
>Jean-Do
>
>
>code snippet
>         //Define cutting plane
>         vtkPlane* plane = vtkPlane::New();
>         plane->SetOrigin(300., 500., 0);
>         plane->SetNormal(-1, -1, 0);
>
>         //Generate cut lines
>         vtkCutter* cutEdges = vtkCutter::New();
>         cutEdges->SetInput(Normals->GetOutput());
>         cutEdges->SetCutFunction(plane);
>
>         //Forms lines from cutter
>         vtkStripper* cutStrips = vtkStripper::New();
>         cutStrips->SetInput(cutEdges->GetOutput());
>         cutStrips->Update();
>
>         //Defines polygons as polyline
>         vtkPolyData* LinePoly = vtkPolyData::New();
>         LinePoly->SetPoints((cutStrips->GetOutput())->GetPoints());
>         LinePoly->SetLines((cutStrips->GetOutput())->GetLines());
>
>         //Write PolyData to file
>         vtkPolyDataWriter* wr = vtkPolyDataWriter::New();
>         wr->SetFileName("Line4.vtk");
>         wr->SetInput(LinePoly);
>         wr->Write();
>
>Output of the vtkPolyDataWriter (file Line4.vtk)
># vtk DataFile Version 3.0
>vtk output
>ASCII
>DATASET POLYDATA
>POINTS 28 float
>252.329 547.171 500 235.668 563.832 500 314.825 484.675 549.214
>305.908 493.592 553.277 224.208 575.292 500 223.112 576.388 500
>342.103 457.397 590.352 339.985 459.515 587.917 446.203 353.297 737.623
>441.629 357.871 700 294.445 505.055 542.116 343.253 456.247 592.317
>415.885 383.615 664.838 409.217 390.283 664.838 350.938 448.562 600
>426.08 373.42 670.902 439.236 360.264 700 492.288 307.212 866.422
>482.154 317.346 884.873 458.735 340.765 779.183 451.048 348.452 750.164
>479.711 319.789 887.034 463.563 335.937 800 512.234 287.266 900
>510.437 289.063 900 496.357 303.143 851.732 502.247 297.253 829.042
>519.514 279.986 900
>LINES 7 41
>4 0 1 4 5
>4 2 3 10 0
>3 6 7 2
>9 8 9 16 15 12 13 14 11 6
>7 17 18 21 22 19 20 8
>5 23 24 26 25 17
>2 27 23
>
>CELL_DATA 7
>POINT_DATA 28
>
>
>_______________________________________________
>This is the private VTK discussion list.
>Please keep messages on-topic. Check the FAQ at: 
><http://public.kitware.com/cgi-bin/vtkfaq>
>Follow this link to subscribe/unsubscribe:
>http://www.vtk.org/mailman/listinfo/vtkusers