read obj and mtl file using vtk

gistfile1.txt

#include <vtkNamedColors.h>
#include <vtkOBJImporter.h>
#include <vtkX3DExporter.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSmartPointer.h>
#include <vtkTexture.h>

int main(int argc, char* argv[])
{
    auto importer = vtkSmartPointer<vtkOBJImporter>::New();
    importer->SetFileName("boy.obj");
    importer->SetFileNameMTL("boy.mtl");
    importer->SetTexturePath(".");
    auto renderer = vtkSmartPointer<vtkRenderer>::New();
    auto renWin = vtkSmartPointer<vtkRenderWindow>::New();
    auto iren = vtkSmartPointer<vtkRenderWindowInteractor>::New();

/*    auto colors = vtkSmartPointer<vtkNamedColors>::New();


    renderer->SetBackground2(colors->GetColor3d("Silver").GetData());
    renderer->SetBackground(colors->GetColor3d("Gold").GetData());
    renderer->GradientBackgroundOn();
    renWin->AddRenderer(renderer);
    renderer->UseHiddenLineRemovalOn();*/
    renWin->AddRenderer(renderer);
    renWin->SetSize(640, 480);

    iren->SetRenderWindow(renWin);
    importer->SetRenderWindow(renWin);
    importer->Update();

    auto actors = renderer->GetActors();
    actors->InitTraversal();
    std::cout << "There are " << actors->GetNumberOfItems() << " actors"
        << std::endl;

    for (vtkIdType a = 0; a < actors->GetNumberOfItems(); ++a)
    {
        std::cout << importer->GetOutputDescription(a) << std::endl;

        vtkActor* actor = actors->GetNextActor();

        // OBJImporter turns texture interpolation off
        if (actor->GetTexture())
        {
            std::cout << "Has texture\n";
            actor->GetTexture()->InterpolateOn();
        }

        vtkPolyData* pd =
            dynamic_cast<vtkPolyData*>(actor->GetMapper()->GetInput());

        vtkPolyDataMapper* mapper =
            dynamic_cast<vtkPolyDataMapper*>(actor->GetMapper());
        mapper->SetInputData(pd);
    }
    renWin->Render();
    auto exporter = vtkSmartPointer<vtkX3DExporter>::New();
    exporter->SetRenderWindow(renWin);
    exporter->SetFileName("mystl.stl");
    exporter->Write();
    iren->Start();

    return EXIT_SUCCESS;
}