[vtkusers] Experience upgrading from 3.2 to 4.x

[Tim Hutton]

A follow-on to my previous email. I've added this information to a new 
entry in the FAQ, plus two corrections to the code:

http://public.kitware.com/cgi-bin/vtkfaq?req=show&file=faq06.009.htp

So now my comment below about the FAQ not having enough concrete examples 
is now longer valid. :)

Tim.

At 14:31 14/02/2002 +0000, you wrote:
>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!
>
>Tim.
>
>
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