VTK/Examples/Cxx/Broken/Visualization/ViewOrder

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The BuildLocator() method in vtkKdTree can be used to order cells from a viewing direction. The vtkKdTree region Ids are returned from the ViewOrderAllRegions() method sorted from front to back in the specified direction.

The visualization for this example is currently broken. vtkKdTree is returning an incorrect number of regions.

ViewOrder.cxx

#include <vtkSmartPointer.h>
#include <vtkProperty.h>
#include <vtkPointData.h>
#include <vtkLookupTable.h>
#include <vtkPointSource.h>
#include <vtkIntArray.h>
#include <vtkKdTree.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>

int main(int, char *[])
{
  // Create a point cloud
  vtkSmartPointer<vtkPointSource> pointSource =
    vtkSmartPointer<vtkPointSource>::New();
  pointSource->SetNumberOfPoints(100);
  pointSource->Update();
 
  std::cout << "There are " << pointSource->GetOutput()->GetNumberOfPoints() 
            << " points." << std::endl;
  
  //Create the tree
  vtkSmartPointer<vtkKdTree> kDTree =
      vtkSmartPointer<vtkKdTree>::New();
  kDTree->SetNumberOfRegionsOrMore(128);
  kDTree->AddDataSet(pointSource->GetOutput());
  kDTree->BuildLocator();
 
  std::cout << "There are " << kDTree->GetNumberOfRegions() << " regions." << std::endl;
  // Order the cells based on a viewing direction
  double direction[3] = {2, 1, 0};
  vtkSmartPointer<vtkIntArray> cellOrder =
    vtkSmartPointer<vtkIntArray>::New();
  kDTree->ViewOrderAllRegionsInDirection(direction, cellOrder);
  
  std::cout << "cellOrder->GetNumberOfTuples(): " << cellOrder->GetNumberOfTuples() << std::endl;
  std::cout << "cellOrder->GetNumberOfComponents(): " << cellOrder->GetNumberOfComponents() << std::endl;
  
  std::cout << "Order of vtkKdTree regions is:\n";
  for(vtkIdType i = 0; i < cellOrder->GetNumberOfTuples() * cellOrder->GetNumberOfComponents(); i++)
    {
    std::cout << cellOrder->GetValue(i) << std::endl;
    }
    
  vtkSmartPointer<vtkPolyData> coloredPoints = 
    vtkSmartPointer<vtkPolyData>::New();
  coloredPoints->ShallowCopy(pointSource->GetOutput());
  
   //create the color map
  vtkSmartPointer<vtkLookupTable> colorLookupTable = 
    vtkSmartPointer<vtkLookupTable>::New();
  colorLookupTable->SetTableRange(0, cellOrder->GetNumberOfTuples());
  colorLookupTable->Build();
 
  //generate the colors for each point based on the color map
  vtkSmartPointer<vtkUnsignedCharArray> colors = 
    vtkSmartPointer<vtkUnsignedCharArray>::New();
  colors->SetNumberOfComponents(3);
  colors->SetName("Colors");
  
  for(vtkIdType i = 0; i < pointSource->GetOutput()->GetNumberOfPoints(); i++)
    {
    double p[3];
    pointSource->GetOutput()->GetPoint(i,p);
    int region = kDTree->GetRegionContainingPoint(p[0], p[1], p[2]);
    double dcolor[3];
    colorLookupTable->GetColor(p[2], dcolor);
    unsigned char color[3];
    for(unsigned int j = 0; j < 3; j++)
      {
      color[j] = 255 * dcolor[j]/1.0;
      }
    colors->InsertNextTupleValue(color);
    }
  
  coloredPoints->GetPointData()->SetScalars(colors);
 
  //Create a mapper and actor
  vtkSmartPointer<vtkPolyDataMapper> mapper = 
    vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper->SetInputConnection(coloredPoints->GetProducerPort());
 
  vtkSmartPointer<vtkActor> actor = 
    vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);
  actor->GetProperty()->SetInterpolationToFlat();
  actor->GetProperty()->SetPointSize(4);
  
  //Create a renderer, render window, and interactor
  vtkSmartPointer<vtkRenderer> renderer = 
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow = 
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor = 
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);
 
  //Add the actor to the scene
  renderer->AddActor(actor);
  renderer->SetBackground(.3, .6, .3); // Background color green
 
  //Render and interact
  renderWindow->Render();
  renderWindowInteractor->Start();
  
  return EXIT_SUCCESS;
}

Please try the new VTKExamples website.

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(ViewOrder)

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

add_executable(ViewOrder MACOSX_BUNDLE ViewOrder.cxx)

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

Download and Build ViewOrder

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

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

cd ViewOrder/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:

./ViewOrder

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.