VRMLImporterDemo

VTKExamples/Cxx/IO/VRMLImporterDemo

Description

vtkVRMLImporter imports multiple vtkActor models. Sometimes the vtkPolyData require modifications. For example the data in this example does not have normals. The example uses vtkActorCollection to walk each model's vtkPolyData and inserts a vtkPolyDataNormals if the normals do not exist.

Bug

vtkVRMLImporter files use a shininess between 0 and 1, while vtk's vtkProperty has a specular power between 0 and 128. The example corrects this if the specular power is <= 1.0.

Bug

vtkVRMLImporter incorrectly creates a vtkLookupTable for colorPerVertex. This example converts the vtkLookupTable to vtkPointData.

Tip

The Virtual Insect website has lots of cool wrl models of insects.

Code

VRMLImporterDemo.cxx

#include <vtkSmartPointer.h>
#include <vtkVRMLImporter.h>

#include <vtkUnsignedCharArray.h>
#include <vtkActor.h>
#include <vtkActorCollection.h>
#include <vtkCamera.h>
#include <vtkMapper.h>
#include <vtkLookupTable.h>
#include <vtkPointData.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkPolyDataNormals.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>

#include <vtkNamedColors.h>

int main ( int argc, char *argv[])
{
  if(argc < 2)
  {
    std::cout << "Required arguments: Filename" << std::endl;
    return EXIT_FAILURE;
  }

  std::string filename = argv[1];
  std::cout << "Reading " << filename << std::endl;

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

  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);

  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);

  // VRML Import
  vtkSmartPointer<vtkVRMLImporter> importer =
    vtkSmartPointer<vtkVRMLImporter>::New();
  importer->SetFileName ( filename.c_str() );
  importer->SetRenderWindow(renderWindow);
  importer->Update();

  vtkSmartPointer<vtkActorCollection> actors =
    vtkSmartPointer<vtkActorCollection>::New();
  actors = renderer->GetActors();
  std::cout << "There are " << actors->GetNumberOfItems() << " actors" << std::endl;
  actors->InitTraversal();
  for (vtkIdType a = 0; a < actors->GetNumberOfItems(); ++a)
  {
    vtkActor * actor = actors->GetNextActor();

    // The importer shininess parameter is between 0 and 1. VTK specular power is usually 10-100.
    // Also, the default for the specular factor for VRML is 1, while VTK's is 0
    double specularPower = actor->GetProperty()->GetSpecularPower();
    if (specularPower <= 1.0)
    {
      actor->GetProperty()->SetSpecularPower(specularPower * 128.0);
    }
    double specular = actor->GetProperty()->GetSpecular();
    if (specular == 0.0)
    {
      actor->GetProperty()->SetSpecular(1.0);
    }
#if 0
    // The VRML default ambient intensity is .2
    double ambientIntensity = actor->GetProperty()->GetAmbient();
    if (ambientIntensity == 0.0)
    {
      actor->GetProperty()->SetAmbient(.2);
    }
#endif
    vtkPolyDataMapper *mapper = dynamic_cast<vtkPolyDataMapper*>(actor->GetMapper());
    if (mapper)
    {
      vtkPolyData *dataSet = dynamic_cast<vtkPolyData*>(mapper->GetInput());
      if (!dataSet->GetPointData()->GetNormals())
      {
        vtkSmartPointer<vtkPolyDataNormals> normals =
          vtkSmartPointer<vtkPolyDataNormals>::New();
        normals->SetInputData(dataSet);
        normals->SplittingOff();
        normals->Update();
        mapper->SetInputData(normals->GetOutput());
      }

      // If there is a lookup table, convert it to point data
      vtkLookupTable *lut = dynamic_cast<vtkLookupTable*>(mapper->GetLookupTable());
      if (lut && mapper->GetScalarVisibility())
      {
        vtkSmartPointer<vtkUnsignedCharArray> pc =
          vtkSmartPointer<vtkUnsignedCharArray>::New();
        pc->SetNumberOfComponents(4);
        pc->SetNumberOfTuples(lut->GetNumberOfColors());
        for (int t = 0; t < lut->GetNumberOfColors(); ++t)
        {
          double *lutc = lut->GetTableValue(t);
          unsigned char lutuc[4];
          lut->GetColorAsUnsignedChars(lutc, lutuc);
          pc->SetTypedTuple(t, lutuc);
        }
        mapper->SetLookupTable(NULL);
        mapper->GetInput()->GetPointData()->SetScalars(pc);
      }
    }
  }

  renderer->ResetCamera();
  renderer->GetActiveCamera()->Azimuth(30);
  renderer->GetActiveCamera()->Elevation(30);
  renderer->GetActiveCamera()->Dolly(1.4);
  renderer->ResetCameraClippingRange();

  renderer->SetBackground(colors->GetColor3d("PaleGreen").GetData());
  renderWindow->SetSize(640, 480);
  renderWindow->Render();
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(VRMLImporterDemo)

find_package(VTK COMPONENTS 
  vtkCommonColor
  vtkCommonCore
  vtkCommonDataModel
  vtkFiltersCore
  vtkIOImport
  vtkInteractionStyle
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingGL2PSOpenGL2
  vtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
  message("Skipping VRMLImporterDemo: ${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(VRMLImporterDemo MACOSX_BUNDLE VRMLImporterDemo.cxx )
  target_link_libraries(VRMLImporterDemo PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(VRMLImporterDemo MACOSX_BUNDLE VRMLImporterDemo.cxx )
  target_link_libraries(VRMLImporterDemo PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS VRMLImporterDemo
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build VRMLImporterDemo

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

cd VRMLImporterDemo/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:

./VRMLImporterDemo

WINDOWS USERS

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