Difference between revisions of "VTK/Examples/Cxx/PolyData/DecimatePolyline"

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<div class="floatright">[[File:VTK_Examples_Baseline_Widgets_DecimatePolyline.png|300px]]</div>
 
<div class="floatright">[[File:VTK_Examples_Baseline_Widgets_DecimatePolyline.png|300px]]</div>
 
== Decimate one Polyline ==
 
== Decimate one Polyline ==
This example shows how to decimate one polyline.
+
This example shows how to [[wikipedia:Decimation (signal processing)|decimate]] a polyline.
 
 
Note that this example requires the git (master branch) version of VTK (as of 8/5/2010).
 
  
 
==DecimatePolyline.cxx==
 
==DecimatePolyline.cxx==

Revision as of 08:04, 6 November 2015

VTK Examples Baseline Widgets DecimatePolyline.png

Decimate one Polyline

This example shows how to decimate a polyline.

DecimatePolyline.cxx

#include <vtkVersion.h>
#include <vtkDecimatePolylineFilter.h>
#include <vtkMath.h>
#include <vtkPolyData.h>
#include <vtkCellArray.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkProperty.h>

#include <vtkSmartPointer.h>

int main(int, char *[])
{
  const unsigned int numberofpoints = 100;

  vtkPolyData* circle = vtkPolyData::New();
  vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();
  vtkSmartPointer<vtkCellArray> lines = vtkSmartPointer<vtkCellArray>::New();
  vtkIdType* lineIndices = new vtkIdType[numberofpoints+1];

  for( unsigned int i = 0; i < numberofpoints; i++ )
    {
    const double angle = 2.0 * vtkMath::Pi() * static_cast< double >( i ) /
      static_cast< double >( numberofpoints );
    points->InsertPoint( static_cast< vtkIdType >( i ),
                         cos( angle ),
                         sin( angle ),
                         0. );
    lineIndices[i] = static_cast< vtkIdType >( i );
    }
  lineIndices[numberofpoints] = 0;
  lines->InsertNextCell( numberofpoints+1, lineIndices );
  delete[] lineIndices;

  circle->SetPoints( points );
  circle->SetLines( lines );

  vtkSmartPointer<vtkPolyDataMapper> c_mapper = 
    vtkSmartPointer<vtkPolyDataMapper>::New();
#if VTK_MAJOR_VERSION <= 5
  c_mapper->SetInput( circle );
#else
  c_mapper->SetInputData( circle );
#endif

  vtkSmartPointer<vtkActor> c_actor = 
    vtkSmartPointer<vtkActor>::New();
  c_actor->SetMapper( c_mapper );

  vtkSmartPointer<vtkDecimatePolylineFilter> decimate = 
    vtkSmartPointer<vtkDecimatePolylineFilter>::New();
#if VTK_MAJOR_VERSION <= 5
  decimate->SetInput( circle );
#else
  decimate->SetInputData( circle );
#endif
  decimate->SetTargetReduction( 0.95 );
  decimate->Update();

  vtkSmartPointer<vtkPolyDataMapper> d_mapper = 
    vtkSmartPointer<vtkPolyDataMapper>::New();
  d_mapper->SetInputConnection( decimate->GetOutputPort() );

  vtkSmartPointer<vtkActor> d_actor = 
    vtkSmartPointer<vtkActor>::New();
  d_actor->SetMapper( d_mapper );
  d_actor->GetProperty()->SetColor( 1., 0. ,0. );

  vtkSmartPointer<vtkRenderer> ren = 
    vtkSmartPointer<vtkRenderer>::New();
  ren->AddActor( c_actor );
  ren->AddActor( d_actor );

  vtkSmartPointer<vtkRenderWindow> renwin = 
    vtkSmartPointer<vtkRenderWindow>::New();
  renwin->AddRenderer( ren );

  vtkSmartPointer<vtkRenderWindowInteractor> iren = 
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  iren->SetRenderWindow( renwin );

  renwin->Render();

  iren->Start();

  circle->Delete();

  return EXIT_SUCCESS;
}

Please try the new VTKExamples website.

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(DecimatePolyline)

find_package(VTK REQUIRED)
include(${VTK_USE_FILE})

add_executable(DecimatePolyline MACOSX_BUNDLE DecimatePolyline.cxx)

if(VTK_LIBRARIES)
  target_link_libraries(DecimatePolyline ${VTK_LIBRARIES})
else()
  target_link_libraries(DecimatePolyline vtkHybrid vtkWidgets)
endif()

Download and Build DecimatePolyline

Click here to download DecimatePolyline. and its CMakeLists.txt file.

Once the tarball DecimatePolyline.tar has been downloaded and extracted,

cd DecimatePolyline/build 
  • If VTK is installed:
cmake ..
  • If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:
cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

make

and run it:

./DecimatePolyline

WINDOWS USERS PLEASE NOTE: Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.