[vtkusers] mapping texture on spehere: deata mirrored

[Robert Belleman]

Hi Sidney,

Here's a way to get the image appear right:

  pictureLayerActor->GetProperty()->BackfaceCullingOff();
  pictureLayerActor->GetProperty()->FrontfaceCullingOn();

But I'm pretty sure you're not going to like the side effects... ;-)

Seriously though; I don't think this is a problem of
vtkTexturedSphereSource (see for example
examples/contrib/examplesTcl/earth.tcl which takes the texture from
VTK_DATA/earth.ppm, which is not mirrored).

I'm afraid you will have to remap you array.

Best,
-- Rob

[] Robert Belleman         X  Section Computational Science            []
[] robbel at science.uva.nl  |X| University of Amsterdam, the Netherlands []
[] tel: (+31) 20 525 7510  X  http://www.science.uva.nl/~robbel/       []

On Mon, Feb 04, 2002 at 12:13:32PM +0100, Sidney Cadot wrote:
> 
> Hi all,
> 
> I have to map a 2D in-memory array of shorts onto a sphere; the 2D data is
> layed out as such:
> 
> 
> array[  0  ][  0  ] --> top left
> array[HOR-1][  0  ] --> top right
> array[  0  ][VER-1] --> bottom left
> array[HOR-1][VER-1] --> bottom right
> 
> when I draw a simple in-memory texture saying "HELLO" and map this onto a
> sphere, I get a mirror-image (see code snippet below). It seems that the
> TexturedSphereSource is programmed in such a way that it maps as if the
> viewer is on the "inside" rather than on the "outside". Please check
> 
>   http://www.v2e.nl/~sidney/hello.jpg
> 
> ...to see what I mean.
> 
> Now of course I can do mirroring using a filter, but I would very much
> prefer if I could get the picture right without requiring extra memory for
> another image, for example by setting some flag for the
> vtkTexturedSphereSource (there seems to be none) or the vtkTexture (I'm
> not sure).
> 
> Does anybody know a good way of doing this?
> 
> Best regards,
> 
>   Sidney Cadot
> 
> ===== code snippet
> 
>   vtkShortArray *array = vtkShortArray::New();
>   array->SetVoidArray(dmap, HOR*VER, 1);
> 
>   vtkImageData *imageData = vtkImageData::New();
>   imageData->SetDimensions(HOR,VER,1);
>   imageData->SetScalarTypeToShort();
>   imageData->GetPointData()->SetScalars(array);
> 
>   vtkTexturedSphereSource *tss = vtkTexturedSphereSource::New();
>   tss->SetRadius(1.000);
>   tss->SetThetaResolution(36);
>   tss->SetPhiResolution(18);
> 
>   vtkPolyDataMapper *pictureLayerMapper = vtkPolyDataMapper::New();
>   pictureLayerMapper->SetInput(tss->GetOutput());
> 
>   vtkTexture *pictureTexture = vtkTexture::New();
>   pictureTexture->SetInput(imageData);
> 
>   vtkActor *pictureLayerActor = vtkActor::New();
>   pictureLayerActor->SetMapper(pictureLayerMapper);
>   pictureLayerActor->SetTexture(pictureTexture);
> 
>   vtkRenderer *renderer = vtkRenderer::New();
>   renderer->AddActor(pictureLayerActor);
> 
>   vtkRenderWindow *renderWindow = vtkRenderWindow::New();
>   renderWindow->AddRenderer(renderer);
> 
>   iren = vtkRenderWindowInteractor::New();
>   iren->SetRenderWindow(renderWindow);
> 
>   renderWindow->Render();
>   iren->Start();
> 
> ===== end of code snippet
> 
> 
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