ConnectivityFilterDemo
VTKEx/Cxx/Filtering/ConnectivityFilterDemo
Description¶
This example uses vtkPolyDataConnectivity to separate an input vtkPolyData into disconnected regions. Each region is assigned a unique color. A number of vtkNamedColors are used to fill part of the vtkLookupTable. If the number of extracted regions is more that the number of specified colors, the remaining colors are generated with a random number generator.
The default representation is surface. If the user types a "w" in the render window, the view will be rendered as a wireframe. The renderer will use hidden line removal.
The example supports any vtkPolyData reader.
Info
ConnectivityFilter illustrates vtkConnectivityFilter on a simple 2 region dataset.
Question
If you have a simple question about this example contact us at VTKExProject If your question is more complex and may require extended discussion, please use the VTK Discourse Forum
Code¶
ConnectivityFilterDemo.cxx
#include <vtkSmartPointer.h>
#include <vtkPolyDataConnectivityFilter.h>
#include <vtkSphereSource.h>
#include <vtkDataSetMapper.h>
#include <vtkLookupTable.h>
#include <vtkCamera.h>
#include <vtkActor.h>
#include <vtkProperty.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkAppendPolyData.h>
#include <vtkScalarsToColors.h>
#include <vtkNamedColors.h>
// Readers
#include <vtkBYUReader.h>
#include <vtkOBJReader.h>
#include <vtkPLYReader.h>
#include <vtkPolyDataReader.h>
#include <vtkSTLReader.h>
#include <vtkXMLPolyDataReader.h>
#include <vtkPolyData.h>
#include <vtkSphereSource.h>
#include <algorithm> // For transform()
#include <string> // For find_last_of()
#include <cctype> // For to_lower
#include <random>
namespace
{
vtkSmartPointer<vtkPolyData> ReadPolyData(std::string const& fileName);
}
int main(int argc, char*argv[])
{
vtkSmartPointer<vtkPolyData> polyData =
ReadPolyData(argc > 1 ? argv[1] : "");
auto connectivityFilter =
vtkSmartPointer<vtkPolyDataConnectivityFilter>::New();
connectivityFilter->SetInputData(polyData);
connectivityFilter->SetExtractionModeToAllRegions();
connectivityFilter->ColorRegionsOn();
connectivityFilter->Update();
// Visualize
int numberOfRegions = connectivityFilter->GetNumberOfExtractedRegions();
if (argc > 1)
{
std::cout << argv[1] << " contains " << numberOfRegions << " regions" << std::endl;
}
else
{
std::cout << "Generated data" << " contains " << numberOfRegions << " regions" << std::endl;
}
auto lut =
vtkSmartPointer<vtkLookupTable>::New();
lut->SetNumberOfTableValues(std::max(numberOfRegions, 10));
lut->Build();
// Fill in a few known colors, the rest will be generated if needed
auto colors =
vtkSmartPointer<vtkNamedColors>::New();
lut->SetTableValue(0, colors->GetColor4d("Gold").GetData());
lut->SetTableValue(1, colors->GetColor4d("Banana").GetData());
lut->SetTableValue(2, colors->GetColor4d("Tomato").GetData());
lut->SetTableValue(3, colors->GetColor4d("Wheat").GetData());
lut->SetTableValue(4, colors->GetColor4d("Lavender").GetData());
lut->SetTableValue(5, colors->GetColor4d("Flesh").GetData());
lut->SetTableValue(6, colors->GetColor4d("Raspberry").GetData());
lut->SetTableValue(7, colors->GetColor4d("Salmon").GetData());
lut->SetTableValue(8, colors->GetColor4d("Mint").GetData());
lut->SetTableValue(9, colors->GetColor4d("Peacock").GetData());
// If the number of regions os larger than the number of specified colors,
// generate some random colors.
if (numberOfRegions > 9)
{
std::mt19937 mt(4355412); //Standard mersenne_twister_engine
std::uniform_real_distribution<double> distribution(.4, 1.0);
for (auto i = 10; i < numberOfRegions; ++i)
{
lut->SetTableValue(i, distribution(mt), distribution(mt), distribution(mt), 1.0);
}
}
auto mapper =
vtkSmartPointer<vtkDataSetMapper>::New();
mapper->SetInputConnection(connectivityFilter->GetOutputPort());
mapper->SetScalarRange(0, connectivityFilter->GetNumberOfExtractedRegions() - 1);
mapper->SetLookupTable(lut);
mapper->Update();
auto actor =
vtkSmartPointer<vtkActor>::New();
actor->SetMapper(mapper);
auto renderer =
vtkSmartPointer<vtkRenderer>::New();
renderer->AddActor(actor);
renderer->UseHiddenLineRemovalOn();
renderer->SetBackground(colors->GetColor3d("Silver").GetData());
auto renderWindow =
vtkSmartPointer<vtkRenderWindow>::New();
renderWindow->AddRenderer(renderer);
renderWindow->SetSize(640, 480);
// Pick a good view
renderer->GetActiveCamera()->SetFocalPoint(0.0, 0.0, 0.0);
renderer->GetActiveCamera()->SetPosition(0.0, 1.0, 0.0);
renderer->GetActiveCamera()->SetViewUp(0.0, 0.0, 1.0);
renderer->GetActiveCamera()->Azimuth(30.0);
renderer->GetActiveCamera()->Elevation(45.0);
renderer->ResetCamera();
renderer->GetActiveCamera()->Dolly(1.25);
renderer->ResetCameraClippingRange();
renderWindow->Render();
auto interactor =
vtkSmartPointer<vtkRenderWindowInteractor>::New();
interactor->SetRenderWindow(renderWindow);
interactor->Initialize();
interactor->Start();
return EXIT_SUCCESS;
}
namespace {
vtkSmartPointer<vtkPolyData> ReadPolyData(std::string const& fileName)
{
vtkSmartPointer<vtkPolyData> polyData;
std::string extension = "";
if (fileName.find_last_of(".") != std::string::npos)
{
extension = fileName.substr(fileName.find_last_of("."));
}
// Make the extension lowercase
std::transform(extension.begin(), extension.end(), extension.begin(),
::tolower);
if (extension == ".ply")
{
auto reader = vtkSmartPointer<vtkPLYReader>::New();
reader->SetFileName(fileName.c_str());
reader->Update();
polyData = reader->GetOutput();
}
else if (extension == ".vtp")
{
auto reader = vtkSmartPointer<vtkXMLPolyDataReader>::New();
reader->SetFileName(fileName.c_str());
reader->Update();
polyData = reader->GetOutput();
}
else if (extension == ".obj")
{
auto reader = vtkSmartPointer<vtkOBJReader>::New();
reader->SetFileName(fileName.c_str());
reader->Update();
polyData = reader->GetOutput();
}
else if (extension == ".stl")
{
auto reader = vtkSmartPointer<vtkSTLReader>::New();
reader->SetFileName(fileName.c_str());
reader->Update();
polyData = reader->GetOutput();
}
else if (extension == ".vtk")
{
auto reader = vtkSmartPointer<vtkPolyDataReader>::New();
reader->SetFileName(fileName.c_str());
reader->Update();
polyData = reader->GetOutput();
}
else if (extension == ".g")
{
auto reader = vtkSmartPointer<vtkBYUReader>::New();
reader->SetGeometryFileName(fileName.c_str());
reader->Update();
polyData = reader->GetOutput();
}
else
{
// Return a polydata sphere if the extension is unknown.
auto source = vtkSmartPointer<vtkSphereSource>::New();
source->SetThetaResolution(20);
source->SetPhiResolution(11);
source->Update();
polyData = source->GetOutput();
}
return polyData;
}
} // namespace
CMakeLists.txt¶
cmake_minimum_required(VERSION 3.3 FATAL_ERROR)
project(ConnectivityFilterDemo)
find_package(VTK COMPONENTS
vtkvtkCommonColor
vtkvtkCommonCore
vtkvtkCommonDataModel
vtkvtkFiltersCore
vtkvtkFiltersSources
vtkvtkIOGeometry
vtkvtkIOLegacy
vtkvtkIOPLY
vtkvtkIOXML
vtkvtkInteractionStyle
vtkvtkRenderingContextOpenGL2
vtkvtkRenderingCore
vtkvtkRenderingFreeType
vtkvtkRenderingGL2PSOpenGL2
vtkvtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
message("Skipping ConnectivityFilterDemo: ${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(ConnectivityFilterDemo MACOSX_BUNDLE ConnectivityFilterDemo.cxx )
target_link_libraries(ConnectivityFilterDemo PRIVATE ${VTK_LIBRARIES})
else ()
# include all components
add_executable(ConnectivityFilterDemo MACOSX_BUNDLE ConnectivityFilterDemo.cxx )
target_link_libraries(ConnectivityFilterDemo PRIVATE ${VTK_LIBRARIES})
# vtk_module_autoinit is needed
vtk_module_autoinit(
TARGETS ConnectivityFilterDemo
MODULES ${VTK_LIBRARIES}
)
endif ()
Download and Build ConnectivityFilterDemo¶
Click here to download ConnectivityFilterDemo and its CMakeLists.txt file. Once the tarball ConnectivityFilterDemo.tar has been downloaded and extracted,
cd ConnectivityFilterDemo/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:
./ConnectivityFilterDemo
WINDOWS USERS
Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.