CellPointNeighbors
vtk-examples/Cxx/PolyData/CellPointNeighbors
Description¶
Determine which cells share at least a single point with a specified cell.
Question
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Code¶
CellPointNeighbors.cxx
#include <vtkActor.h>
#include <vtkCell.h>
#include <vtkDataSetMapper.h>
#include <vtkExtractSelection.h>
#include <vtkIdList.h>
#include <vtkIdTypeArray.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPolyData.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSelection.h>
#include <vtkSelectionNode.h>
#include <vtkSphereSource.h>
#include <vtkTriangleFilter.h>
#include <list>
int main(int, char*[])
{
// Create a sphere
vtkNew<vtkSphereSource> sphereSource;
sphereSource->Update();
vtkNew<vtkTriangleFilter> triangleFilter;
triangleFilter->SetInputConnection(sphereSource->GetOutputPort());
triangleFilter->Update();
// Find all cells connected to point 0
vtkIdType cellId = 0;
vtkNew<vtkIdList> cellPointIds;
triangleFilter->GetOutput()->GetCellPoints(cellId, cellPointIds);
// neighbor cells may be listed multiple times
// use std::set instead of std::list if you want a unique list of neighbors
std::list<vtkIdType> neighbors;
/* For each vertex of the cell, we calculate which cells use that point.
So if we do this for each vertex, we have all the neighbors.
In the case of using "cellPointIds" as a parameter of "GetCellNeighbors",
we will obtain an empty set. This is because the only cell that is using that
set of points is the current one. That is why we have to make each vertice at
time.*/
for (vtkIdType i = 0; i < cellPointIds->GetNumberOfIds(); i++)
{
vtkNew<vtkIdList> idList;
idList->InsertNextId(cellPointIds->GetId(i));
// get the neighbors of the cell
vtkNew<vtkIdList> neighborCellIds;
triangleFilter->GetOutput()->GetCellNeighbors(cellId, idList,
neighborCellIds);
for (vtkIdType j = 0; j < neighborCellIds->GetNumberOfIds(); j++)
{
neighbors.push_back(neighborCellIds->GetId(j));
}
}
std::cout << "Point neighbor ids are: " << std::endl;
for (auto it1 = neighbors.begin(); it1 != neighbors.end(); ++it1)
{
std::cout << " " << *it1;
}
std::cout << std::endl;
vtkNew<vtkNamedColors> colors;
vtkNew<vtkDataSetMapper> sphereMapper;
sphereMapper->SetInputConnection(sphereSource->GetOutputPort());
sphereMapper->SetResolveCoincidentTopologyToPolygonOffset();
vtkNew<vtkActor> sphereActor;
sphereActor->SetMapper(sphereMapper);
sphereActor->GetProperty()->SetEdgeColor(
colors->GetColor3d("Lamp_Black").GetData());
sphereActor->GetProperty()->EdgeVisibilityOn();
sphereActor->GetProperty()->SetLineWidth(3);
vtkNew<vtkDataSetMapper> mainCellMapper;
vtkNew<vtkDataSetMapper> neighborCellsMapper;
// Create a dataset with the cell of interest
{
vtkNew<vtkIdTypeArray> ids;
ids->SetNumberOfComponents(1);
ids->InsertNextValue(cellId);
vtkNew<vtkSelectionNode> selectionNode;
selectionNode->SetFieldType(vtkSelectionNode::CELL);
selectionNode->SetContentType(vtkSelectionNode::INDICES);
selectionNode->SetSelectionList(ids);
vtkNew<vtkSelection> selection;
selection->AddNode(selectionNode);
vtkNew<vtkExtractSelection> extractSelection;
extractSelection->SetInputConnection(0, sphereSource->GetOutputPort());
extractSelection->SetInputData(1, selection);
extractSelection->Update();
mainCellMapper->SetInputConnection(extractSelection->GetOutputPort());
}
vtkNew<vtkActor> mainCellActor;
mainCellActor->SetMapper(mainCellMapper);
mainCellActor->GetProperty()->SetColor(
colors->GetColor3d("Tomato").GetData());
// Create a dataset with the neighbor cells
{
vtkNew<vtkIdTypeArray> ids;
ids->SetNumberOfComponents(1);
for (auto it1 = neighbors.begin(); it1 != neighbors.end(); ++it1)
{
ids->InsertNextValue(*it1);
}
vtkNew<vtkSelectionNode> selectionNode;
selectionNode->SetFieldType(vtkSelectionNode::CELL);
selectionNode->SetContentType(vtkSelectionNode::INDICES);
selectionNode->SetSelectionList(ids);
vtkNew<vtkSelection> selection;
selection->AddNode(selectionNode);
vtkNew<vtkExtractSelection> extractSelection;
extractSelection->SetInputConnection(0, sphereSource->GetOutputPort());
extractSelection->SetInputData(1, selection);
extractSelection->Update();
neighborCellsMapper->SetInputConnection(extractSelection->GetOutputPort());
}
vtkNew<vtkActor> neighborCellsActor;
neighborCellsActor->SetMapper(neighborCellsMapper);
neighborCellsActor->GetProperty()->SetColor(
colors->GetColor3d("Mint").GetData());
// Create a renderer, render window, and interactor
vtkNew<vtkRenderer> renderer;
vtkNew<vtkRenderWindow> renderWindow;
renderWindow->AddRenderer(renderer);
renderWindow->SetWindowName("CellPointNeighbors");
vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
renderWindowInteractor->SetRenderWindow(renderWindow);
// Add the actors to the scene
renderer->AddActor(sphereActor);
renderer->AddActor(mainCellActor);
renderer->AddActor(neighborCellsActor);
renderer->SetBackground(colors->GetColor3d("SlateGray").GetData());
// Render and interact
renderWindow->SetSize(640, 480);
renderWindow->Render();
renderWindowInteractor->Start();
return EXIT_SUCCESS;
}
CMakeLists.txt¶
cmake_minimum_required(VERSION 3.12 FATAL_ERROR)
project(CellPointNeighbors)
find_package(VTK COMPONENTS
vtkCommonColor
vtkCommonCore
vtkCommonDataModel
vtkFiltersCore
vtkFiltersExtraction
vtkFiltersSources
vtkInteractionStyle
vtkRenderingContextOpenGL2
vtkRenderingCore
vtkRenderingFreeType
vtkRenderingGL2PSOpenGL2
vtkRenderingOpenGL2
QUIET
)
if (NOT VTK_FOUND)
message("Skipping CellPointNeighbors: ${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(CellPointNeighbors MACOSX_BUNDLE CellPointNeighbors.cxx )
target_link_libraries(CellPointNeighbors PRIVATE ${VTK_LIBRARIES})
else()
# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
add_executable(CellPointNeighbors MACOSX_BUNDLE CellPointNeighbors.cxx )
target_link_libraries(CellPointNeighbors PRIVATE ${VTK_LIBRARIES})
# vtk_module_autoinit is needed
vtk_module_autoinit(
TARGETS CellPointNeighbors
MODULES ${VTK_LIBRARIES}
)
endif()
Download and Build CellPointNeighbors¶
Click here to download CellPointNeighbors and its CMakeLists.txt file. Once the tarball CellPointNeighbors.tar has been downloaded and extracted,
cd CellPointNeighbors/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:
./CellPointNeighbors
WINDOWS USERS
Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.