VTK/Examples/Cxx/PolyData/DeleteCells

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Delete a cell from vtkPolyData

This example demonstrates how to delete a cell from a vtkPolyData. This is a three-step process: first, build upward-links from points to cells; second, mark cells for deletion; third, delete the marked cells. The first step is necessary to create a data structure suitable for efficient delete operations. Creating such a structure is expensive so it is needed when carrying out topologically complex operations.

DeleteCells.cxx

#include <vtkActor.h>
#include <vtkCellArray.h>
#include <vtkLine.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkSmartPointer.h>
 
int main(int, char *[])
{
  vtkSmartPointer<vtkPoints> points =
    vtkSmartPointer<vtkPoints>::New();
  points->InsertNextPoint(0,0,0);
  points->InsertNextPoint(1,0,0);
  points->InsertNextPoint(1,1,0);
  points->InsertNextPoint(0,1,0);
 
  vtkSmartPointer<vtkLine> line0 = 
    vtkSmartPointer<vtkLine>::New();
  line0->GetPointIds()->SetId(0, 0);
  line0->GetPointIds()->SetId(1, 1);
 
  vtkSmartPointer<vtkLine> line1 = 
    vtkSmartPointer<vtkLine>::New();
  line1->GetPointIds()->SetId(0, 1);
  line1->GetPointIds()->SetId(1, 2);
 
  vtkSmartPointer<vtkLine> line2 = 
    vtkSmartPointer<vtkLine>::New();
  line2->GetPointIds()->SetId(0, 2);
  line2->GetPointIds()->SetId(1, 3);
 
  vtkSmartPointer<vtkCellArray> lines =
    vtkSmartPointer<vtkCellArray>::New();
  lines->InsertNextCell(line0);
  lines->InsertNextCell(line1);
  lines->InsertNextCell(line2);
 
  vtkSmartPointer<vtkPolyData> polydata =
    vtkSmartPointer<vtkPolyData>::New();
  polydata->SetPoints(points);
  polydata->SetLines(lines);

  // Tell the polydata to build 'upward' links from points to cells.
  polydata->BuildLinks();
  // Mark a cell as deleted.
  polydata->DeleteCell(1);
  // Remove the marked cell.
  polydata->RemoveDeletedCells();

  // Visualize
  vtkSmartPointer<vtkPolyDataMapper> mapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper->SetInputConnection(polydata->GetProducerPort());
 
  vtkSmartPointer<vtkActor> actor =
    vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);
 
  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor = 
      vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);
  renderer->AddActor(actor);
 
  renderWindow->Render();
  renderWindowInteractor->Start();
 
  return EXIT_SUCCESS;
}

CMakeLists.txt

PROJECT(FilledContours)
CMAKE_MINIMUM_REQUIRED(VERSION 2.6)
 
FIND_PACKAGE(VTK REQUIRED)
INCLUDE(${VTK_USE_FILE})
 
ADD_EXECUTABLE(DeleteCells DeleteCells.cxx)
TARGET_LINK_LIBRARIES(DeleteCells vtkHybrid)