DecimatePolyline

VTKExamples/Cxx/PolyData/DecimatePolyline

Description¶

This example shows how to decimate a polyline.

Question

Code¶

DecimatePolyline.cxx

#include <vtkSmartPointer.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 <vtkNamedColors.h>

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

vtkSmartPointer<vtkPolyData> circle =
vtkSmartPointer<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();
c_mapper->SetInputData( circle );

vtkSmartPointer<vtkNamedColors> colors =
vtkSmartPointer<vtkNamedColors>::New();

vtkSmartPointer<vtkActor> c_actor =
vtkSmartPointer<vtkActor>::New();
c_actor->SetMapper( c_mapper );
c_actor->GetProperty()->SetColor(colors->GetColor3d("Banana").GetData());
c_actor->GetProperty()->SetLineWidth(3);

vtkSmartPointer<vtkDecimatePolylineFilter> decimate =
vtkSmartPointer<vtkDecimatePolylineFilter>::New();
decimate->SetInputData( circle );
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(colors->GetColor3d("Tomato").GetData());
d_actor->GetProperty()->SetLineWidth(3);

vtkSmartPointer<vtkRenderer> ren =
vtkSmartPointer<vtkRenderer>::New();

vtkSmartPointer<vtkRenderWindow> renwin =
vtkSmartPointer<vtkRenderWindow>::New();

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

ren->SetBackground(colors->GetColor3d("SlateGray").GetData());
renwin->SetSize(640, 480);

renwin->Render();

iren->Start();

return EXIT_SUCCESS;
}


CMakeLists.txt¶

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(DecimatePolyline)

find_package(VTK COMPONENTS
vtkCommonColor
vtkCommonCore
vtkCommonDataModel
vtkFiltersCore
vtkInteractionStyle
vtkRenderingCore
vtkRenderingFreeType
vtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
message("Skipping DecimatePolyline: ${VTK_NOT_FOUND_MESSAGE}") return () endif() message (STATUS "VTK_VERSION:${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
# old system
include(${VTK_USE_FILE}) add_executable(DecimatePolyline MACOSX_BUNDLE DecimatePolyline.cxx ) target_link_libraries(DecimatePolyline PRIVATE${VTK_LIBRARIES})
else ()
# include all components
target_link_libraries(DecimatePolyline PRIVATE ${VTK_LIBRARIES}) # vtk_module_autoinit is needed vtk_module_autoinit( TARGETS DecimatePolyline MODULES${VTK_LIBRARIES}
)
endif ()


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

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