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VRMLImporterDemo

vtk-examples/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 [vtkActor](https://www.vtk.org/doc/nightly/html/classvtkActor.html#details)Collection 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 <vtkMapper.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.