[vtkusers] vtkOpenGLSkybox and cubic texture map orientation

[Ken Martin]

Here is a rough example (maybe not 100% but close, I just grabbed the key
parts form TestCubeMap2.cxx. It uses 6 square textures and assembles them
into a cube map.

  const char* fpath[] =
    {
    "Data/skybox/posx.jpg",
    "Data/skybox/negx.jpg",
    "Data/skybox/posy.jpg",
    "Data/skybox/negy.jpg",
    "Data/skybox/posz.jpg",
    "Data/skybox/negz.jpg"
    };

  vtkNew<vtkTexture> texture;
  texture->CubeMapOn();
  texture->InterpolateOn();
  texture->RepeatOff();
  texture->EdgeClampOn();

  // mipmapping works on many systems but is not
  // core 3.2 for cube maps. VTK will silently
  // ignore it if it is not supported.
  texture->MipmapOn();

  for (int i = 0; i < 6; i++)
  {
    vtkNew<vtkJPEGReader> imgReader;
    imgReader->SetFileName(
      vtkTestUtilities::ExpandDataFileName(argc, argv, fpath[i]));
    vtkNew<vtkImageFlip> flip;
    flip->SetInputConnection(imgReader->GetOutputPort());
    flip->SetFilteredAxis(1); // flip y axis
    texture->SetInputConnection(i, flip->GetOutputPort(0));
  }

  vtkNew<vtkSkybox> world;
  world->SetTexture(texture);
  renderer->AddActor(world);


On Sat, Jan 27, 2018 at 3:11 PM, BBerco <bebe0705 at colorado.edu> wrote:

> I am trying to display a skybox environment using the vtkOpenGLSkybox
> class.
>
> The documentation of vtkSkybox says that a texture cube must be provided. I
> used  this one
> <https://www.google.com/search?q=cubic+texture+file&
> source=lnms&tbm=isch&sa=X&ved=0ahUKEwjiw7q09PjYAhVSyGMKHYKVA
> q8Q_AUICigB&biw=1280&bih=703#imgrc=-t5W2ikSKVWtQM:>
>
> I'm providing the skybox actor with a cube source. But s you can see below,
> the texture is not properly mapped.
>
> Any advice?
>
> <http://vtk.1045678.n5.nabble.com/file/t341520/Screen_Shot_
> 2018-01-27_at_13.png>
>
>
> main.cpp:
> *
> #include <vtkSphereSource.h>
> #include <vtkCubeSource.h>
> #include <vtkPolyData.h>
> #include <vtkSmartPointer.h>
> #include <vtkPolyDataMapper.h>
> #include <vtkActor.h>
> #include <vtkRenderWindow.h>
> #include <vtkRenderer.h>
> #include <vtkRenderWindowInteractor.h>
> #include <vtkOpenGLSkybox.h>
> #include <vtkImageReader2Factory.h>
> #include <vtkTexture.h>
> #include <vtkTransformTextureCoords.h>
> #include <vtkImageReader2.h>
>
> int main(int, char *[])
> {
>
>
>
>    // Read texture file
>   vtkSmartPointer<vtkImageReader2Factory> readerFactory =
> vtkSmartPointer<vtkImageReader2Factory>::New();
>   vtkImageReader2 *imageReader = readerFactory
> ->CreateImageReader2("../map.png");
>
>   imageReader->SetFileName("../map.png");
>
>   // Create texture
>   vtkSmartPointer<vtkTexture> texture =vtkSmartPointer<vtkTexture>::New();
>   texture->SetInputConnection(imageReader->GetOutputPort());
>
>
>   // Create a cube
>   vtkSmartPointer<vtkCubeSource> skybox_source =
>   vtkSmartPointer<vtkCubeSource>::New();
>
>
>   vtkSmartPointer<vtkPolyDataMapper> skybox_mapper =
>   vtkSmartPointer<vtkPolyDataMapper>::New();
>   skybox_mapper->SetInputConnection(skybox_source->GetOutputPort());
>
>   // Create the skybox
>   vtkSmartPointer<vtkOpenGLSkybox> skybox =
> vtkSmartPointer<vtkOpenGLSkybox>::New();
>
>   skybox -> SetTexture(texture);
>   skybox -> SetMapper(skybox_mapper);
>
>
>
>
>
>   // Create a sphere
>   vtkSmartPointer<vtkSphereSource> sphereSource =
>   vtkSmartPointer<vtkSphereSource>::New();
>   sphereSource->SetCenter(0.0, 0.0, 0.0);
>   sphereSource->SetRadius(5.0);
>
>   vtkSmartPointer<vtkPolyDataMapper> mapper =
>   vtkSmartPointer<vtkPolyDataMapper>::New();
>   mapper->SetInputConnection(sphereSource->GetOutputPort());
>
>   vtkSmartPointer<vtkActor> actor =
>   vtkSmartPointer<vtkActor>::New();
>   actor->SetMapper(mapper);
>
>   vtkSmartPointer<vtkRenderer> renderer =
>   vtkSmartPointer<vtkRenderer>::New();
>   vtkSmartPointer<vtkRenderWindow> renderWindow =
>   vtkSmartPointer<vtkRenderWindow>::New();
>   renderWindow->AddRenderer(renderer);
>   vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
>   vtkSmartPointer<vtkRenderWindowInteractor>::New();
>   renderWindowInteractor->SetRenderWindow(renderWindow);
>
>   // renderer->AddActor(actor);
>   renderer->AddActor(skybox);
>
>   // renderer->SetBackground(.3, .6, .3); // Background color green
>
>   renderWindow->Render();
>   renderWindowInteractor->Start();
>
>   return EXIT_SUCCESS;
> }
> *
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> --
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-- 
Ken Martin PhD
Distinguished Engineer
Kitware Inc.
28 Corporate Drive
Clifton Park NY 12065

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