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.

Question

If you have a question about this example, please use the VTK Discourse Forum

Code¶

VRMLImporterDemo.cxx

#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkLookupTable.h>
#include <vtkNamedColors.h>
#include <vtkNew.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 <vtkUnsignedCharArray.h>
#include <vtkVRMLImporter.h>

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

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

  vtkNew<vtkNamedColors> colors;

  vtkNew<vtkRenderer> renderer;
  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->AddRenderer(renderer);
  renderWindow->SetWindowName("VRMLImporterDemo");

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

  // VRML Import
  vtkNew<vtkVRMLImporter> importer;
  importer->SetFileName(filename.c_str());
  importer->SetRenderWindow(renderWindow);
  importer->Update();

  auto 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())
      {
        vtkNew<vtkPolyDataNormals> normals;
        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())
      {
        vtkNew<vtkUnsignedCharArray> pc;
        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("SpringGreen").GetData());
  renderWindow->SetSize(640, 480);
  renderWindow->Render();
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt¶

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(VRMLImporterDemo)

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

if (NOT VTK_FOUND)
  message(FATAL_ERROR "VRMLImporterDemo: 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(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}
)

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.