[vtkusers] Experience upgrading from 3.2 to 4.x

[Ken Martin]

Hello Tim,

Thanks for posting this information. That should prove useful to some
other folks contemplating VTK4.0. I'm curious, how much time did it
take to convert your 40K lines of code app from 3.2 to 4.0 ?

Thanks
Ken


> Hello vtkusers!
>
> I've just ported my medium-sized (40K lines) application
> from vtk3.2 to
> vtk4.x. I thought I would share my experiences with you, in
> case there were
> people out there contemplating it but a bit scared.
>
> The documentation in
>
> http://public.kitware.com/VTK/files/misc/Upgrading.zip
>
> and the FAQ entry 6.7 at
>
> http://public.kitware.com/cgi-bin/vtkfaq?req=show&file=faq06.007.htp
>
> are both useful but don't have enough concrete examples.
> Hopefully this
> email will help a little, though it is by no means
> complete. I'm using
> VC++6 + MFC on Win2K and was unable/unwilling to run the
> script in the zip
> file.
>
> So,
>
> I switched all my include directories to the new VTK ones
> and recompiled.
> 337 errors, not unexpectedly. Most concerned vtkScalars and
> vtkTCoords
> which have both been removed. Where I was using single
> value scalars, like
> this:
>
> vtkScalars *scalars = vtkScalars::New();
> scalars->SetNumberOfScalars(N_POINTS);
> ...
> polydata->GetPointData()->SetScalars(scalars);
> ...
> scalars->SetScalar(i,2.3);
> ...
>
> I replaced with:
>
> vtkFloatArray *scalars = vtkFloatArray::New();
> scalars->SetNumberOfComponents(1);
> scalars->SetNumberOfTuples(N_POINTS);
> ...
> polydata->GetPointData()->SetScalars(scalars);
> ...
> scalars->SetTuple1(i,2.3);
> ...
>
> OK so far, far fewer errors.
>
> Where I had 2D texture coordinates:
>
> vtkTCoords *tcoords = vtkTCoords::New();
> tcoords->SetNumberOfTCoords(N);
> ...
> float p[3];
> p[0]=x; p[1]=y;
> tcoords->SetTCoord(i,p);
> ...
>
> I replaced with:
>
> vtkFloatArray *tcoords = vtkTCoords::New();
> tcoords->SetNumberOfComponents(2);
> tcoords->SetNumberOfTuples(N);
> ...
> float p[2];
> p[0]=x; p[1]=y;
> tcoords->SetTuple(i,p);
> ....
>
> All well and good, still fewer errors. Make sure you call
> SetNumberOfComponents *before* SetNumberOfTuples else
> you'll get problems
> (I did!).
>
> Where I was creating 0-255 image data and had been using:
>
> vtkScalars* scalars = vtkScalars::New();
> scalars->SetDataTypeToUnsignedChar();
> ...
>
> I replaced with:
>
> vtkUnsignedCharArray *scalars = vtkUnsignedCharArray::New()
> ...
>
> Going well!
>
> When creating RGB images, I had been using:
>
> vtkScalars *scalars = vtkScalars::New();
> scalars->SetDataTypeToUnsignedChar();
> scalars->SetNumberOfComponents(3);
> scalars->SetNumberOfScalars(X*Y);
> ...
> scalars->SetActiveComponent(0);
> scalars->SetScalar(i,val1);
> scalars->SetActiveComponent(1);
> scalars->SetScalar(i,val2);
> scalars->SetActiveComponent(2);
> scalars->SetScalar(i,val3);
> ...
>
> I replaced with:
>
> vtkUnsignedCharArray *scalars = vtkUnsignedCharArray::New()
> scalars->SetNumberOfComponents(3);
> scalars->SetNumberOfScalars(X*Y);
> ...
> scalars->SetComponent(i,0,val1);
> scalars->SetComponent(i,1,val2);
> scalars->SetComponent(i,2,val3);
> ...
>
> My remaining errors concerned vtkWin32OffscreenRenderWindow
> that has been
> removed. Where I had been using:
>
> vtkWin32OffscreenRenderWindow *offscreen =
> vtkWin32OffscreenRenderWindow::New();
> ...
>
> I replaced with:
>
> vtkWin32OpenGLRenderWindow *offscreen =
> vtkWin32OpenGLRenderWindow::New();
> offscreen->SetOffScreenRendering(1);
> ...
>
> All done. I'd had to throw in some #include
> "vtkFloatArray.h" and things
> like that of course. Zero compile errors.
>
> Had to remember to link against the new vtk lib files, so I removed
>
> vtkdll.lib
>
> and added
>
> vtkCommon.lib
> vtkGraphics.lib
> etc.
>
> Zero link errors. My program is up and running again, no
> apparant problems.
> Plus now I can use all the new features of vtk4. (And I'm
> sure it's faster
> but maybe that's my imagination.)
>
> Bye!