Update and Execute

[Nils Holger Busch]

Hello,

I have three questions regarding vtk.

The first concerns the opengl support. I am using vtk on an SGI 02. When
construction renderer, render windows, lights, cameras etc can I go with
the common vtkRenderer vtkRenderWindow and so forth or should I
explicitly construct a vtkOpenGlRenderer etc. for speed. Or will the
common objects default to the hardware supported OpenGl equivalents?

The second question concerns the difference of update and execute
methods.
I have written a reader for my data structure. much like the
vtkTIFFReader that reads an image from file and constructs the
appropriate vtk structures. However, it seems inefficient to me to have
a file access in the updateinformation routine like in the vtkTIFFReader
that gets called for every event . Shouldn't the one time creation of
the static data structures be done in the class ctor?
Also, when comparing the tiff reader to the vtkVolume16Reader I noticed
that those things are placed there in the execute method.
So, where should the static creation of data structures go? What is the
difference in putting them in the update or execute method?
In general what should be put in update and execute? What is the design
rationale behind this?

And last, I receive a linker error when executing a program that creates
a vtkImage. The linker reports:

ld: Error: unresolvable symbol in
/home/elster1/busch/local/lib/libVTKGraphics.so: XtShellStrings
47830:SinSource: rld: Error: unresolvable symbol in
/home/elster1/busch/local/lib/libVTKGraphics.so: XtStrings
47830:SinSource: rld: Error: unresolvable symbol in
/home/elster1/busch/local/lib/libVTKGraphics.so:
applicationShellWidgetClass
47830:SinSource: rld: Fatal Error: this executable has unresolvable
symbols

Where do these things come from? Which class calls them? And how to fix
that?

Thanks for any help.

--
Best regards,
                                         Nils H. Busch

======================================================
=== Max-Planck-Institute of Cognitive Neuroscience ===
=== Phone:                     ++49 (341) 9940-234 ===
=== Fax:                       ++49 (341) 9940-221 ===
=== E-Mail:                       nilsb at cns.mpg.de ===
======================================================





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