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BlankPoint

vtk-examples/Cxx/StructuredGrid/BlankPoint

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Question

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Code

BlankPoint.cxx

#include <vtkActor.h>
#include <vtkDataSetMapper.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkStructuredGrid.h>
#include <vtkStructuredGridGeometryFilter.h>

#include <iostream>

int main(int, char*[])
{
  vtkNew<vtkNamedColors> colors;

  // Create a grid
  vtkNew<vtkStructuredGrid> structuredGrid;

  vtkNew<vtkPoints> points;

  unsigned int gridSize = 8;
  unsigned int counter = 0;
  unsigned int ptIdx = 0;
  // Create a 5x5 grid of points
  for (unsigned int j = 0; j < gridSize; j++)
  {
    for (unsigned int i = 0; i < gridSize; i++)
    {
      if (i == 3 && j == 3) // Make one point higher than the rest
      {
        points->InsertNextPoint(i, j, 2);
        std::cout << "The different point is number " << counter << std::endl;
        ptIdx = counter;
      }
      else
      {
        // Make most of the points the same height
        points->InsertNextPoint(i, j, 0);
      }
      counter++;
    }
  }

  // Specify the dimensions of the grid, set the points and blank one point.
  structuredGrid->SetDimensions(gridSize, gridSize, 1);
  structuredGrid->SetPoints(points);
  structuredGrid->BlankPoint(ptIdx);
  structuredGrid->Modified();

  // Check.
  auto isVisible = [&structuredGrid](int const& ptNum) {
    if (structuredGrid->IsPointVisible(ptNum))
    {
      std::cout << "Point: " << ptNum << " is visible" << std::endl;
    }
    else
    {
      std::cout << "Point: " << ptNum << " is not visible" << std::endl;
    }
  };

  // Should not be visible.
  isVisible(ptIdx);
  // Should be visible.
  isVisible(7);

  // We need the geometry filter to ensure that the
  // blanked point and surrounding faces is missing.
  vtkNew<vtkStructuredGridGeometryFilter>geometryFilter;
  geometryFilter->SetInputData(structuredGrid);

  // Create a mapper and actor.
  vtkNew<vtkDataSetMapper> gridMapper;
  // gridMapper->SetInputData(structuredGrid);
  gridMapper->SetInputConnection(geometryFilter->GetOutputPort());


  vtkNew<vtkActor> gridActor;
  gridActor->SetMapper(gridMapper);
  gridActor->GetProperty()->EdgeVisibilityOn();
  gridActor->GetProperty()->SetEdgeColor(colors->GetColor3d("Blue").GetData());

  // Create a renderer, render window, and interactor.
  vtkNew<vtkRenderer> renderer;
  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->AddRenderer(renderer);
  renderWindow->SetWindowName("BlankPoint");

  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
  renderWindowInteractor->SetRenderWindow(renderWindow);

  // Add the actor to the scene.
  renderer->AddActor(gridActor);
  renderer->SetBackground(colors->GetColor3d("ForestGreen").GetData());

  // Render and interact.
  renderWindow->Render();

  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(BlankPoint)

find_package(VTK COMPONENTS 
  CommonColor
  CommonCore
  CommonDataModel
  InteractionStyle
  RenderingContextOpenGL2
  RenderingCore
  RenderingFreeType
  RenderingGL2PSOpenGL2
  RenderingOpenGL2
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "BlankPoint: Unable to find the VTK build folder.")
endif()

# 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(BlankPoint MACOSX_BUNDLE BlankPoint.cxx )
  target_link_libraries(BlankPoint PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS BlankPoint
  MODULES ${VTK_LIBRARIES}
)

Download and Build BlankPoint

Click here to download BlankPoint and its CMakeLists.txt file. Once the tarball BlankPoint.tar has been downloaded and extracted,

cd BlankPoint/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:

./BlankPoint

WINDOWS USERS

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